<?xml version='1.0' encoding='utf-8'?> <!DOCTYPE rfc [ <!ENTITY nbsp " "> <!ENTITY zwsp "​"> <!ENTITY nbhy "‑"> <!ENTITY wj "⁠"> ]><?xml-stylesheet type="text/xsl" href="rfc2629.xslt" ?> <!-- generated by https://github.com/cabo/kramdown-rfc version 1.7.29 (Ruby 3.2.3) --><?rfc strict="yes"?> <?rfc comments="yes"?> <?rfc docmapping="yes"?> <rfc xmlns:xi="http://www.w3.org/2001/XInclude" ipr="trust200902" docName="draft-ietf-pquip-pqc-engineers-14" category="info" consensus="true" submissionType="IETF" xml:lang="en" number="9958" tocInclude="true" sortRefs="true" symRefs="true" version="3"><!-- xml2rfc v2v3 conversion 3.30.1 --><link href="https://datatracker.ietf.org/doc/draft-ietf-pquip-pqc-engineers-14" rel="prev"/> <front> <title abbrev="PQC for Engineers">Post-Quantum Cryptography for Engineers</title> <seriesInfoname="Internet-Draft" value="draft-ietf-pquip-pqc-engineers-14"/>name="RFC" value="9958"/> <author fullname="Aritra Banerjee"> <organization>Nokia</organization> <address> <postal> <city>London</city> <country>United Kingdom</country> </postal> <email>aritra.banerjee@nokia.com</email> </address> </author> <author fullname="TirumaleswarReddy">Reddy.K"> <organization>Nokia</organization> <address> <postal> <city>Bangalore</city> <region>Karnataka</region> <country>India</country> </postal> <email>k.tirumaleswar_reddy@nokia.com</email> </address> </author> <author fullname="Dimitrios Schoinianakis"> <organization>Nokia</organization> <address> <postal> <city>Athens</city> <country>Greece</country> </postal> <email>dimitrios.schoinianakis@nokia-bell-labs.com</email> </address> </author> <author fullname="Timothy Hollebeek"> <organization>DigiCert</organization> <address> <postal> <city>Pittsburgh</city><country>USA</country><region>PA</region> <country>United States of America</country> </postal> <email>tim.hollebeek@digicert.com</email> </address> </author> <author initials="M." surname="Ounsworth" fullname="Mike Ounsworth"> <organization abbrev="Entrust">Entrust Limited</organization> <address> <postal> <street>2500 SolandtRoad –Road, Suite 100</street> <city>Ottawa, Ontario</city> <code>K2K 3G5</code> <country>Canada</country> </postal><email>mike.ounsworth@entrust.com</email><email>mike@ounsworth.ca</email> </address> </author> <dateyear="2025" month="August" day="26"/> <area>Security</area> <workgroup>PQUIP</workgroup>year="2026" month="May"/> <area>SEC</area> <workgroup>pquip</workgroup> <keyword>PQC</keyword> <abstract><?line 263?><!-- Status of I-Ds in references section: [I-D.bonnell-lamps-chameleon-certs] draft-bonnell-lamps-chameleon-certs-07 IESG State: I-D Exists as of 11/26/25 [I-D.connolly-cfrg-xwing-kem] draft-connolly-cfrg-xwing-kem-09 IESG State: I-D Exists as of 11/26/25 [I-D.hale-mls-combiner] draft-hale-mls-combiner-01 Replaced by draft-ietf-mls-combiner [I-D.ietf-hpke-pq] draft-ietf-hpke-pq-03 IESG State: I-D Exists as of 11/26/25 [I-D.ietf-lamps-pq-composite-sigs] draft-ietf-lamps-pq-composite-sigs-13 IESG state: Publication Requested as of 11/26/25 [I-D.ietf-pquip-hybrid-signature-spectrums] draft-ietf-pquip-hybrid-signature-spectrums-07 IESG state: RFC Ed Queue as of 11/26/25 [I-D.ietf-pquip-pqc-hsm-constrained] draft-ietf-pquip-pqc-hsm-constrained-02 IESG State: I-D Exists as of 11/26/25 [I-D.ietf-sshm-ntruprime-ssh] draft-ietf-sshm-ntruprime-ssh-06 Published as RFC 9941 [I-D.ietf-tls-hybrid-design] draft-ietf-tls-hybrid-design-16 IESG state: RFC Ed Queue as of 11/26/25 [I-D.irtf-cfrg-bbs-signatures] draft-irtf-cfrg-bbs-signatures-09 IESG State: I-D Exists as of 11/26/25 [I-D.irtf-cfrg-hybrid-kems] draft-irtf-cfrg-hybrid-kems-07 IESG State: I-D Exists as of 11/26/25 [I-D.ounsworth-cfrg-kem-combiners] draft-ounsworth-cfrg-kem-combiners-05 IESG State: Expired as of 11/26/25 --> <t>The advent of a cryptographically relevant quantum computer (CRQC) would render state-of-the-art, traditional public key algorithms deployed today obsolete, as the mathematical assumptions underpinning their security would no longer hold. To address this, protocols and infrastructure must transition to post-quantum algorithms, which are designed to resist both traditional and quantum attacks. This document explains why engineers need to be aware of and understand post-quantum cryptography (PQC),detailingand it details the impact of CRQCs on existing systems and the challenges involved in transitioning to post-quantum algorithms. Unlike previous cryptographic updates, this shift may require significant protocol redesign due to the unique properties of post-quantum algorithms.</t> </abstract><note removeInRFC="true"> <name>About This Document</name> <t> Status information for this document may be found at <eref target="https://datatracker.ietf.org/doc/draft-ietf-pquip-pqc-engineers/"/>. </t> <t> Discussion of this document takes place on the pquip Working Group mailing list (<eref target="mailto:pqc@ietf.org"/>), which is archived at <eref target="https://mailarchive.ietf.org/arch/browse/pqc/"/>. Subscribe at <eref target="https://www.ietf.org/mailman/listinfo/pqc/"/>. </t> </note></front> <middle><?line 267?><section anchor="introduction"> <name>Introduction</name> <t>Quantum computing is no longer just a theoretical concept in computational science and physics; it is now an active area of research with practical implications. Considerable research efforts and enormous corporate and government funding for the development of practical quantum computing systems are currently being invested. At the time this document is published, cryptographically relevant quantum computers (CRQCs) that can break widely used asymmetric algorithms (also known as public key algorithms) are not yet available. However, there is ongoing research and development in the field of quantum computing, with the goal of building more powerful and scalable quantum computers.</t> <t>One common myth is that quantum computers are faster than conventional CPUs and GPUs in all areas. This is not the case; much as GPUs outperform general-purpose CPUs only on specific types of problems,so willquantumcomputers, too,computers also have a niche set of problems on which they excel. Unfortunately for cryptographers, integer factorization and discrete logarithms, the mathematical problems underpinning much of classical public key cryptography, happen to fall within the nichethatin which quantum computers are expected toexcel at.excel. As quantum technology advances, there is the potential for future quantum computers to have a significant impact on current cryptographic systems. Predicting the date of emergence of a CRQC is a challenging task, and there is ongoing uncertainty regarding when they will become practically feasible <xref target="CRQCThreat"/>.</t> <t>Extensive research has produced several post-quantum cryptographic algorithms that offer the potential to ensure cryptography's survival in the quantum computing era. However, transitioning to a post-quantum infrastructure is not a straightforward task, and there are numerous challenges to overcome. It requires a combination of engineering efforts, proactive assessment and evaluation of available technologies, and a careful approach to product development and deployment.</t> <t>PQC is sometimes referred to as "quantum-proof", "quantum-safe", or "quantum-resistant". It is the development of cryptographic algorithms designed to secure communication and data in a world where quantum computers are powerful enough to break traditional cryptographic systems, such as RSA(Rivest–Shamir–Adleman)(Rivest-Shamir-Adleman) and ECC (Elliptic Curve Cryptography). PQC algorithms are intended to be resistant to attacks by quantum computers, which use quantum-mechanical phenomena to solve mathematical problems that are infeasible for classical computers.</t> <t>As the threat of CRQCs draws nearer, engineers responsible for designing, maintaining, and securing cryptographic systems must prepare for the significant changes that the existence of CRQCs will bring. Engineers need to understand how to implement post-quantum algorithms in applications, how to evaluate the trade-offs between security and performance, and how to ensure backward compatibility with current systems where needed. This is not merely a one-for-one replacement of algorithms; in many cases, the shift to PQC will involve redesigning protocols and infrastructure to accommodate the significant differences in resource utilization and key sizes between traditional and PQC algorithms. Due to the wide-ranging nature of these impacts, discussions of protocol changes are integrated throughout this document rather than being confined to a single section.</t> <t>This document aims to provide general guidance to engineers working on cryptographic libraries, network security, and infrastructure development, where long-term security planning is crucial. The document covers topics such as selecting appropriate PQCalgorithms,algorithms and understanding the differences between PQCkey encapsulation mechanismsKey Encapsulation Mechanisms (KEMs) and traditional Diffie-Hellman (DH) andRSA styleRSA-style key exchanges, and it provides insights into expectedkey,differences in keys, ciphertext,andsignaturesizessizes, and processingtime differencestimes between PQC and traditional algorithms. Additionally, it discusses the potential threat to symmetric cryptography and hash functions from CRQCs.</t> <t>It is important to remember that asymmetric algorithms (also known as public key algorithms) are largely used for secure communications between organizations or endpoints that may not have previously interacted, so a significant amount of coordination between organizations, and within and betweenecosystemsecosystems, needs to be taken into account. Such transitions are some of the most complicated in the tech industry and will require staged migrations in which upgraded agents need toco-existcoexist and communicate with non-upgraded agents at a scale never before undertaken.</t> <t>The National Security Agency (NSA) of the United States released an article on future PQC algorithm requirements for US national security systems <xref target="CNSA2-0"/> based on the need to protect against deployments of CRQCs in the future. The German Federal Office for Information Security (BSI) has also released a PQC migration and recommendations document <xref target="BSI-PQC"/>whichthat largely aligns with United States National Institute of Standards and Technology (NIST) and NSAguidance,guidance but differs in aspects such as specific PQC algorithm profiles.</t> <t>CRQCs pose a threat to both symmetric and asymmetric cryptographic schemes. However, the threat to asymmetric cryptography is significantly greater due to Shor's algorithm <xreftarget="Shors"/> algorithm,target="Shors"/>, which can breakwidely-usedwidely used public key schemes like RSA and ECC. Symmetric cryptography and hash functions face a lower risk from Grover's algorithm <xreftarget="Grovers"/> algorithm,target="Grovers"/>, although the impact is less severe and can typically be mitigated by doubling key and digest lengths where the risk applies. It is crucial for the reader to understand that whenthe word"PQC" is mentioned in the document, it means asymmetric cryptography (or public keycryptography),cryptography) and not any symmetric algorithms based on stream ciphers, block ciphers, hash functions,MACs,Message Authentication Codes (MACs), etc., which are less vulnerable to quantum computers. This document does not coversuchtopics such as when traditional algorithms might become vulnerable (for that, see documents such as <xref target="QC-DNS"/> and others).</t> <t>This document does not cover unrelated technologies like quantum key distribution (QKD) or quantum key generation, which use quantum hardware to exploit quantum effects to protect communications and generate keys, respectively. PQC is based on conventional math (not on quantum mechanics) andsoftwaresoftware, and it can be run on anygeneral purposegeneral-purpose computer.</t> <t>This document does not go into the deep mathematics or technical specification of the PQCalgorithms,algorithms but rather provides an overview to engineers on the current threat landscape and the relevant algorithms designed to help prevent those threats. Also, the cryptographic and algorithmic guidance given in this document should be taken as non-authoritative if it conflicts with emerging and evolving guidance from the IRTF's Crypto Forum Research Group (CFRG).</t> </section> <section anchor="terminology"> <name>Terminology</name><t>Quantum computer: A<dl> <dt>Quantum computer:</dt> <dd> <t>A computer that performs computations using quantum-mechanical phenomena such as superposition and entanglement.</t><t>Physical qubit: The</dd> <dt>Physical qubit:</dt> <dd> <t>The basic physical unit in a quantum computer, which is prone to noise and errors.</t><t>Logical qubit: A</dd> <dt>Logical qubit:</dt> <dd> <t>A fault-tolerant qubit constructed from multiple physical qubits using quantum error correction; it is the effective unit for reliable quantum computation.</t><t>Post-Quantum</dd> <dt>Post-Quantum Cryptography(PQC): Cryptographic(PQC):</dt> <dd> <t>Cryptographic algorithms designed to be secure against quantum and classical attacks.</t><t>Cryptographically</dd> <dt>Cryptographically Relevant Quantum Computer(CRQC): A(CRQC):</dt> <dd> <t>A quantum computer with sufficient logical qubits to break traditional asymmetric cryptographic algorithms (e.g., RSA or ECC) within a practical timeframe.</t><t>Public</dd> <dt>Public Key Cryptography (also called AsymmetricCryptography): ACryptography):</dt> <dd> <t>A class of cryptographic algorithms in which separate keys are used for encryption anddecryption,decryption or for signing and verification. Throughout this document, the terms Public Key Cryptography and Asymmetric Cryptography are used interchangeably.</t> </dd> </dl> <t>There is ongoing discussion about whether to use the term "post-quantum", "quantum ready", "quantum resistant", or "quantumsecure",secure" to describe algorithms that resist CRQCs, and a consensus has not yet been reached. NIST has coined the term "post-quantum" to refer to the algorithms that participated in its competition-like selection process; in this context, the term can be interpreted to mean "the set of algorithms that are designed to still be relevant after quantum computersexist",exist" and not a statement about their security. "Quantum resistant" or "quantum secure" is obviously the goal of thesealgorithms, howeveralgorithms; however, some people have raised concerns thatlabellinglabeling a class of algorithms as "quantum resistant" or "quantum secure" could lead to confusion if one or more of those algorithms are later found to be insecure or to not resist quantum computers as much as theory predicted. "Quantum ready" is often used to refer to a solution -- device, appliance, or software stack -- that has reached maturity withregardsregard to integration of these new cryptographic algorithms. That said, the authors recognize that there is great variability in how these terms are used. This document usesany ofthese terms interchangeably to refer to such algorithms.</t><t>The terms "current," "state-of-the-art," and "ongoing," as used in<t>In this document, the terms "current", "state-of-the-art", and "ongoing" refer to work, research, investigations, deployments, or developments that are applicable at the time of publication.</t> </section> <section anchor="threat-of-crqcs-on-cryptography"> <name>Threat of CRQCs on Cryptography</name> <t>When considering the security risks associated with the ability of a quantum computer to attack traditional cryptography, it is important to distinguish between the impact on symmetric algorithms and public key ones. Dr. Peter Shor and Dr. Lov Grover developed two algorithms that changed the way the world thinks of security under the presence of a CRQC.</t> <t>Quantum computers are, by their nature, hybrids of classical and quantum computational units. For example, Shor's algorithm consists of a combination of quantum and classical computational steps. Thus, the term "quantum adversary" should be thought of as "quantum-enhanced adversary", meaning they have access to both classical and quantum computational techniques.</t><t>Despite that<t>Although large-scale quantum computers do not yet exist to experiment on, the theoretical properties of quantum computation are very well understood. This allows engineers and researchers to reason about the upper limits of quantum-enhancedcomputation,computation andindeedto design cryptographic algorithms that are resistant to any conceivable form of quantum cryptanalysis.</t> <section anchor="symmetric"> <name>Symmetric Cryptography</name> <t>For unstructured data such as symmetric encrypted data or cryptographic hashes, although CRQCs can search for specific solutions across all possible input combinations (e.g., Grover's algorithm), no quantum algorithm is known to break the underlying security properties of these classes of algorithms. Symmetric-key cryptography, which includes keyed primitives such as block ciphers (e.g., AES) and message authentication mechanisms (e.g., HMAC-SHA256), relies on secret keys shared between the sender and receiver and remains secure even in a post-quantum world. Symmetric cryptography also includes hash functions (e.g., SHA-256) that are used for secure message digesting without any shared key material.HMACHashed Message Authentication Code (HMAC) is a specific construction that utilizes a cryptographic hash function and a secret key shared between the sender and receiver to produce a message authentication code.</t> <t>Grover's algorithm is a quantum search algorithm that provides a theoretical quadratic speedup for searching an unstructured database, compared to traditional search algorithms. This has led to the common misconception that symmetric key lengths need to be doubled for quantum security. When you consider the mapping of hash values to their corresponding hash inputs (also known aspre-image),pre-image) or of ciphertext blocks to the corresponding plaintextblocks,blocks as an unstructured database, thenGrover’sGrover's algorithm theoretically requires doubling the key sizes of the symmetric algorithms that are currently deployed at the time of publication to counter the quadratic speedup and maintain the current security level. This is becauseGrover’sGrover's algorithm reduces the amount of operations to break 128-bit symmetric cryptography to2^{64}2<sup>{64}</sup> quantum operations, which might sound computationally feasible. However, quantum operations are fundamentally different from classicalonesones, as2^{64}2<sup>{64}</sup> classical operations can be efficientlyparallelized, 2^{64}parallelized but 2<sup>{64}</sup> quantum operations must be performed serially, making them infeasible on practical quantum computers.</t> <t>Grover's algorithm is highly non-parallelizable and even if one deploys2^c2<sup>c</sup> computational units in parallel to brute-force a key using Grover's algorithm, it will complete in time proportional to2^{(128−c)/2},2<sup>{(128-c)/2}</sup>, or, put simply, using 256 quantum computers will only reduce runtime by a factor of 16, 1024 quantum computers will only reduce runtime by a factor of3232, and so forth (see <xref target="NIST"/> and <xref target="Cloudflare"/>). Due to this inherent limitation, the general expert consensus is that AES-128(Advanced Encryption Standard)remains secure inpractice,practice and key sizes do not necessarily need to be doubled.</t> <t>It would be natural to ask whether future research will develop a superior algorithm that could outperform Grover's algorithm in the general case. However, Christof Zalka has shown that Grover's algorithm achieves the best possible complexity for this type of search, meaning no significantly faster quantum approach is expected <xreftarget="Grover-search"/></t>target="Grover-Search"/>.</t> <t>Finally, in their evaluation criteria for PQC, NIST is assessing the security levels of proposed post-quantum algorithms by comparing them against the equivalent traditional and quantum security of AES-128, AES-192, and AES-256. This indicates that NIST is confident in the stable security properties of AES, even in the presence of both traditional and quantum attacks. As a result, 128-bit algorithms can be considered quantum-safe for the foreseeable future. However, for compliance purposes, some organizations, such as the French National Agency for the Security of Information Systems (ANSSI) <xref target="ANSSI"/> andCNSA 2.0 (Commercialthe National SecurityAlgorithm SuiteAgency (NSA) (CNSA 2.0) <xref target="CNSA2-0"/>, recommend the use of AES-256.</t> </section> <section anchor="asymmetric-cryptography"> <name>Asymmetric Cryptography</name><t>“Shor’s algorithm”<t>"Shor's algorithm" efficiently solves the integer factorization problem (and the related discrete logarithm problem), which underpin the foundations of the vast majority of public key cryptography that the world uses today. This implies that, if a CRQC is developed,today’stoday's public key algorithms (e.g., RSA,Diffie-HellmanDiffie-Hellman, andelliptic curve cryptography,ECC, as well as lesscommonly-usedcommonly used variants such as ElGamal <xref target="RFC6090"/> and Schnorr signatures <xref target="RFC8235"/>) and protocols would need to be replaced by algorithms and protocols that can offer cryptanalytic resistance against CRQCs. Note thatShor’sShor's algorithm cannot run solely on a classicalcomputer,computer; it requires a CRQC.</t> <t>For example, studies show that, if a CRQC existed, it could break RSA-2048 in hours or even seconds depending on assumptions about error correction <xreftarget="RSAShor"/><xref target="RSA8HRS"/><xreftarget="RSAShor"/> <xref target="RSA8HRS"/> <xref target="RSA10SC"/>. While such machines are purely theoretical at the time of writing, this illustrates the eventual vulnerability of RSA to CRQCs.</t> <t>For structured data such as public keys and signatures, CRQCs can fully solve the underlying hard problems used in traditional cryptography (see Shor's algorithm). Because an increase in the size of thekey-pairkey pair would not provide a secure solution (short of RSA keys that are many gigabytes in size <xref target="PQRSA"/>), a complete replacement of the algorithm is needed. Therefore, post-quantum public key cryptography must rely on problems that are different from the ones used in traditional public key cryptography (i.e., the integer factorization problem, the finite-field discrete logarithm problem, and the elliptic-curve discrete logarithm problem).</t> </section> <section anchor="quantum-side-channel-attacks"> <name>QuantumSide-channelSide-Channel Attacks</name> <t>Cryptographic side-channel attacks exploit physicalimplementations, suchimplementations (such as timing, power consumption, or electromagneticleakageleakage) to recover secret keys.</t> <t>The field of cryptographic side-channel attacks potentially stands to gain a boost in attacker power once cryptanalytic techniques can be enhanced with quantum computation techniques <xref target="QuantSide"/>. While a full discussion of quantum side-channel techniques is beyond the scope of this document, implementers of cryptographic hardware should be aware that currentbest-practicesbest practices for side-channel resistance may not be sufficient against quantum adversaries.</t> </section> </section> <section anchor="traditional-cryptographic-primitives-that-could-be-replaced-by-pqc"> <name>Traditional Cryptographic PrimitivesthatThat Could Be Replaced by PQC</name> <t>Any asymmetric cryptographic algorithm based on integer factorization, finite field discrete logarithms, orelliptic curveelliptic-curve discrete logarithms will be vulnerable to attacks using Shor's algorithm on a CRQC. This document focuses on the principal functions of asymmetric cryptography:</t><ul spacing="normal"> <li> <t>Key<dl> <dt>Key agreement and keytransport: Keytransport:</dt> <dd> <t>Key agreement schemes, typically referred to as Diffie-Hellman (DH) or Elliptic Curve Diffie-Hellman (ECDH), as well as key transport, typically using RSA encryption, are used to establish a shared cryptographic key for secure communication. They are one of the mechanisms that can be replaced by PQC, as they are based on existing public key cryptography and are therefore vulnerable to Shor's algorithm. A CRQC can employ Shor's algorithm to efficiently find the prime factors of a large public key (in the case of RSA),whichwhich, inturnturn, can be exploited to derive the private key. In the case ofDiffie-Hellman,DH, a CRQC has the potential to calculate the discrete logarithm of the(short(short- or long-term)Diffie-HellmanDH public key. This, in turn, would reveal the secret required to derive the symmetric encryption key.</t></li> <li></dd> <dt>Digital signatures:</dt> <dd> <t>Digitalsignatures: Digitalsignature schemes are used to authenticate the identity of a sender, detect unauthorized modifications to data, and underpin trust in a system. Similar to key agreement, signatures also depend on a public-private key pair based on the same mathematics as for key agreement and keytransport, and hencetransport. Because of this, a break in existing public key cryptography will also affect traditional digital signatures, hence the importance of developing post-quantum digital signatures.</t></li> <li></dd> <dt>Boneh-Boyen-Shacham (BBS) signatures:</dt> <dd> <t>BBSsignatures: BBS (Boneh-Boyen-Shacham)signatures are a privacy-preserving signature scheme that offers zero-knowledge proof-like properties by allowing selective disclosure of specific signed attributes without revealing the entire set of signed data. The security of BBS signatures relies on the hardness of the discrete logarithm problem, making them vulnerable to Shor's algorithm. A CRQC can break the data authenticity security property of BBS but not the data confidentiality(Section 6.9 of <xref(<xref section="6.9" sectionFormat="of" target="I-D.irtf-cfrg-bbs-signatures"/>).</t></li> <li></dd> <dt>Content encryption:</dt> <dd> <t>Contentencryption: Contentencryption typically refers to the encryption of the data using symmetric key algorithms, such as AES, to ensure confidentiality. The threat to symmetric cryptography is discussed in <xref target="symmetric"/>.</t></li> </ul></dd> </dl> </section> <section anchor="nist-pqc-algorithms"> <name>NIST PQC Algorithms</name> <t>At the time of writing, NISThavehas standardized three PQC algorithms, with more expected to bestandardisedstandardized in the future(<xref(see <xref target="NISTFINAL"/>). These algorithms are not necessarily drop-in replacements for traditional asymmetric cryptographic algorithms. For instance, RSA <xref target="RSA"/> and ECC <xref target="RFC6090"/> can be used as both akey encapsulation method (KEM)KEM andasa signature scheme, whereas there is currently no post-quantum algorithm that can perform both functions. When upgrading protocols, it is important to replace the existing use of traditional algorithms with either a PQC KEM or a PQC signature method, depending on how the traditional algorithm was previously being used. Additionally, KEMs, as described in <xref target="KEMs"/>, present a different API than either key agreement or key transport primitives. As a result, they may require protocol-level or application-level changes in order to be incorporated.</t> <section anchor="nist-candidates-selected-for-standardization"> <name>NIST Candidates Selected for Standardization</name> <section anchor="pqc-key-encapsulation-mechanisms-kems"> <name>PQC Key Encapsulation Mechanisms (KEMs)</name><ul spacing="normal"> <li> <t><xref target="ML-KEM"/>: Module-Lattice-based<dl> <dt>ML-KEM:</dt> <dd> <t>Module-Lattice-Based Key-EncapsulationMechanism Standard (FIPS-203).</t> </li> <li> <t><xref target="HQC"/>: Hamming Quasi-CyclicMechanism. See FIPS 203 <xref target="ML-KEM"/>.</t> </dd> <dt>HQC:</dt> <dd> <t>Hamming Quasi-Cyclic. See <xref target="HQC"/>. The coding algorithmwhich isbased on the hardness of the syndrome decoding problem for quasi-cyclic concatenated Reed-Muller and Reed-Solomon (RMRS) codes in the Hamming metric. Reed-Muller (RM) codes are a class of block error-correcting codes commonly used in wireless and deep-space communications, while Reed-Solomon (RS) codes are widely used to detect and correct multiple-bit errors. HQC has been selected as part of the NIST post-quantum cryptography project but has not yet been standardized.</t></li> </ul></dd> </dl> </section> <section anchor="pqc-signatures"> <name>PQC Signatures</name><ul spacing="normal"> <li> <t><xref target="ML-DSA"/>: Module-Lattice-Based<dl> <dt>ML-DSA:</dt> <dd> <t>Module-Lattice-Based Digital SignatureStandard (FIPS-204).</t> </li> <li> <t><xref target="SLH-DSA"/>: StatelessAlgorithm. See FIPS 204 <xref target="ML-DSA"/>.</t> </dd> <dt>SLH-DSA:</dt> <dd> <t>Stateless Hash-Based Digital Signature(FIPS-205).</t> </li> <li> <t><xref target="FN-DSA"/>: FN-DSA is a lattice signature scheme (FIPS-206) (<xref target="lattice-based"/>Algorithm. See FIPS 205 <xref target="SLH-DSA"/>.</t> </dd> <dt>FN-DSA:</dt> <dd> <t>Fast-Fourier Transform over NTRU-Lattice-Based Digital Signature Algorithm. See <xref target="FN-DSA"/>; note that NIST has named this algorithm "FN-DSA" and assigned "FIPS 206" for its specification, but at the time of this document's publication, it has not yet been released.</t> </dd> </dl> <t>For more information about these, see Sections <xref target="lattice-based" format="counter"/>, <xref target="hash-based" format="counter"/>, and <xreftarget="sig-scheme"/>).</t> </li> </ul>target="sig-scheme" format="counter"/>.</t> </section> </section> </section> <section anchor="iso-candidates-selected-for-standardization"> <name>ISO Candidates Selected for Standardization</name> <t>At the time of writing, ISO has selected three PQC KEM algorithms as candidates forstandardization, whichstandardization; these are mentioned in the following subsection.</t> <section anchor="pqc-key-encapsulation-mechanisms-kems-1"> <name>PQC Key Encapsulation Mechanisms (KEMs)</name><ul spacing="normal"> <li> <t><xref target="FrodoKEM"/>: Key Encapsulation mechanism<dl> <dt>FrodoKEM:</dt> <dd> <t>KEM based on the hardness of learning with errors in algebraically unstructuredlattices.</t> </li> <li> <t><xref target="ClassicMcEliece"/>: Basedlattices. See <xref target="FrodoKEM"/>.</t> </dd> <dt>ClassicMcEliece:</dt> <dd> <t>KEM based on the hardness of syndrome decoding of Goppa codes. Goppa codes are a class of error-correcting codes that can correct a certain number of errors in a transmitted message. The decoding problem involves recovering the original message from the received noisycodeword.</t> </li> <li> <t><xref target="NTRU"/>: Key encapsulation mechanismcodeword. See <xref target="ClassicMcEliece"/>.</t> </dd> <dt>NTRU:</dt> <dd> <t>KEM based on the "N-th degree Truncated polynomial Ring Units" (NTRU) lattices. Variants include Streamlined NTRU Prime (sntrup761), which is leveraged for use in SSH <xreftarget="I-D.ietf-sshm-ntruprime-ssh"/>.</t> </li> </ul>target="RFC9941"/>. See <xref target="NTRU"/>.</t> </dd> </dl> </section> </section> <section anchor="timeline"> <name>Timeline for Transition</name> <t>Thetimeline,timeline and driving motivation for transitiondiffersdiffer slightly between data confidentiality (e.g., encryption) and data authentication (e.g., signature)use-cases.</t>use cases.</t> <t>For data confidentiality, one is concerned with the so-called "harvest now, decrypt later" (HNDL) attack where a malicious actor with adequate resources can launch an attack to store sensitive encrypted data today that they hope to decrypt once a CRQC is available. This implies that, every day, sensitive encrypted data is susceptible to the attack by not implementing quantum-safe strategies, as it corresponds to data possibly being deciphered in the future.</t> <t>For authentication, it is often the case that signatures have a very short lifetime between signing and verifying (such as during a TLShandshake)handshake), but some authenticationuse-casesuse cases do require long lifetimes, such as signing firmware or software that will be active for decades, signing legal documents, or signing certificates that will be embedded into hardware devices such assmartcards.smart cards. Even for short-livedsignaturessignature use cases, the infrastructure often relies on long-lived rootkeyskeys, which can be difficult to update or replace on in-field devices.</t> <figure anchor="Mosca"> <name>Moscamodel</name>Model</name> <artset> <artwork type="svg"><svg xmlns="http://www.w3.org/2000/svg" version="1.1" height="160" width="448" viewBox="0 0 448 160" class="diagram" text-anchor="middle" font-family="monospace" font-size="13px" stroke-linecap="round"> <path d="M 8,32 L 8,128" fill="none" stroke="black"/> <path d="M 208,32 L 208,80" fill="none" stroke="black"/> <path d="M 296,80 L 296,128" fill="none" stroke="black"/> <path d="M 440,32 L 440,80" fill="none" stroke="black"/> <path d="M 8,32 L 440,32" fill="none" stroke="black"/> <path d="M 8,80 L 440,80" fill="none" stroke="black"/> <path d="M 312,96 L 440,96" fill="none" stroke="black"/> <path d="M 8,128 L 296,128" fill="none" stroke="black"/> <polygon class="arrowhead" points="448,96 436,90.4 436,101.6" fill="black" transform="rotate(0,440,96)"/> <polygon class="arrowhead" points="320,96 308,90.4 308,101.6" fill="black" transform="rotate(180,312,96)"/> <g class="text"> <text x="104" y="68">y</text> <text x="320" y="68">x</text> <text x="136" y="116">z</text> <text x="356" y="116">Security</text> <text x="408" y="116">gap</text> </g> </svg> </artwork> <artwork type="ascii-art"><![CDATA[ +------------------------+----------------------------+ | | | | y | x | +------------------------+----------+-----------------+ | | <---------------> | z | Security gap +-----------------------------------+ ]]></artwork> </artset> </figure> <t>These challenges are illustrated nicely by the so-called Mosca model discussed in <xref target="Threat-Report"/>. In <xref target="Mosca"/>, "x" denotes the time that systems and data need to remain secure, "y" the number of years to fully migrate to a PQC infrastructure, and "z" the time until a CRQC that can break current cryptography is available. The model assumes either that encrypted data can be intercepted and stored before the migration is completed in "y" years, or that signatures will still be relied upon for "x" years after their creation. This data remains vulnerable for the complete "x" years of theirlifetime, thuslifetime; thus, the sum "x+y" gives us an estimate of the full timeframe that dataremainremains insecure. The model essentially asks how one is preparing IT systems during those "y" years (in other words, how one can minimize those "y" years) to minimize the transition phase to a PQC infrastructure and hence minimize the risks of data being exposed in the future.</t> <t>Finally, other factors that could accelerate the introduction of a CRQC should not beunder-estimated, likeunderestimated, forexampleexample, faster-than-expected advances in quantum computing and more efficient versions ofShor’sShor's algorithm requiring fewer qubits. Innovation often comes in waves, so it is to theindustry’sindustry's benefit to remain vigilant and prepare as early as possible.BearAlso, bear in mindalsothat while the industry tracks advances from public research institutions such as universities and companies that publish their results, there is also a great deal of large-budget quantum research being conducted privately by various national interests. Therefore, the true state of quantum computer advancement is likely several years ahead of the publicly available research at the date this document is published.</t> <t>Organizations should alsoconsidercarefully and honestly consider what their migration timeline "y" actually is. If youthinkonly think of the time between receiving a patch from your technologyvendor,vendor and rolling that patch out, then "y" might seem as short as a few weeks. However, this represents the minority of migration cases; more often, a PQC migration will involve at least some amount of hardware replacement. For example, performance-sensitive applications will need CPUs with PQC hardware acceleration. Security-sensitive applications will need PQC TPMs,TEEs, Secure Enclaves,Trusted Execution Environments (TEEs), secure enclaves, and other cryptographic co-processors.SmartcardSmart card applications will require replacement of the cardsas well as of theand readers. The readerswhichcan come in manyform-factors:form factors: tap-for-entry door and turnstile readers, PIN pad machines, laptops with built-insmartcardsmart card readers, and many others.</t> <t>Included in "y" is not only the deploymenttime,time but also the preparation time: integration, testing, auditing, andre-certificationrecertification of cryptographic environments.Consider alsoAlso consider upstream effects that contribute to "y", includinglead-timeslead times foryourvendors to produce PQC-ready products, which may itself include auditing and certification delays, time for regulating bodies to adopt PQC policies, time for auditors to become familiar with the new requirements, etc. If you measure the full migration time "y" from when your vendors begin implementing PQCfunctionality,functionality to when you switch off your last non-PQC-capable device, then "y" can be quitelong;long, likely measured in years for even mostmoderately-sized organizations, thismoderately sized organizations. This long tail should not discourage early action.</t> <t>Organizations responsible for protecting long-lived sensitive data or operating critical infrastructure will need to begin transitioning immediately, particularly in scenarios where data is vulnerable to HNDL attacks.PQ/TPost-quantum and traditional (PQ/T) <xref target="PQT"/> or PQ key exchange is relatively self-contained, typically requiring changes only to the cryptographic library (e.g., OpenSSL). In contrast, migrating to post-quantum or PQ/T digital signatures involves broader ecosystem changes, including updates to certificates,CAs,certificate authorities (CAs), Certificate Management Protocols, HSMs, and trust anchors. Starting early with hybrid key exchange deployments allows organizations to gain operational experience, while prototyping and planning for PQ/T or PQ digital signature integration helps identify ecosystem-wide impacts early. This phased approach reduces long-term migration risks and ensures readiness for more complex updates.</t> </section> <section anchor="pqc-categories"> <name>PQC Categories</name> <t>The post-quantum cryptographic schemes standardized by NIST can be categorized into three main groups: lattice-based, hash-based, and code-based. Other approaches, such as isogeny-based, multivariate-based, and MPC-in-the-Head-based cryptography, are also being explored in research and standardization efforts. In addition, NIST issued a call for additional digital signature proposals to expand the set of post-quantum signatures under evaluation <xref target="AddSig"/>.</t> <section anchor="lattice-based"> <name>Lattice-Based Public Key Cryptography</name> <t>Lattice-based public key cryptography leverages the simple construction of lattices (i.e., a regular collection of points in a Euclidean space that are evenly spaced) to create "trapdoor" problems. These problems are efficient to compute if you possess the secret information but challenging to compute otherwise. Examples of such problems include the shortest vector, closest vector, short integer solution, learning with errors, module learning with errors, and learning with rounding problems. All of these problems feature strong proofs for worst-to-average case reduction, effectively relating the hardness of the average case to the worst case.</t> <t>Lattice-based public keys and signatures are larger than those of classical schemes such as RSA or ECC, but typically by less than an order of magnitude for public keys (about6–10×)6-10x) and by roughly one to two orders of magnitude for signatures (about10–100×),10-100x) rather than by several orders of magnitude, making them the best available candidates for general-purposeuseuse, such as replacing the use of RSA in PKIX certificates.</t> <t>Examples of this class of algorithms include ML-KEM, FN-DSA,ML-DSAML-DSA, and FrodoKEM.</t> <t>It is noteworthy that lattice-based encryption schemes require a rounding step duringdecryptiondecryption, which has a non-zero probability of "rounding the wrong way" and leading to a decryption failure, meaning that valid encryptions are decrypted incorrectly. However, the parameters of NIST PQC candidates are carefully chosen so that the probability of such a failure is cryptographically negligible, far lower than the probability of random transmission errors and implementation bugs. In practical terms, these rare decryption failures can be treated the same way as any fatal transport error:bothBoth sides simply perform a fresh KEM operation, generating a new ciphertext and shared secret.</t> <t>In cryptanalysis, an oracle refers to a system that an attacker can query to learn whether decryption succeeded or failed. If such an oracle exists, an attacker could significantly reduce the security of lattice-based schemes that have a relatively high failure rate. However, for most of the NIST PQC proposals, the number of required oracle queries to force a decryption failure is above practical limits, ashas beenshown in <xref target="LattFail1"/>. More recent works have improved upon the results in <xref target="LattFail1"/>, showing that the cost of searching for additional failing ciphertexts after one or more have already beenfound,found can be sped up dramatically <xref target="LattFail2"/>. Nevertheless, at the time this document is published, the PQC candidates by NIST are considered secure under theseattacksattacks, and constant monitoring as cryptanalysis research is ongoing.</t> </section> <section anchor="hash-based"> <name>Hash-Based Public Key Cryptography</name><t>Hash based PKC<t>Hash-based Public Key Cryptography (PKC) has been around since the 1970s, when it was developed by Lamport and Merkle. It is used to create digital signaturealgorithmsalgorithms, and its security is based on the security of the underlying cryptographic hash function. Many variants of hash-based signatures(HBS)(HBSs) have been developed since the70s1970s, including the recent XMSS <xref target="RFC8391"/>, HSS/LMS <xreftarget="RFC8554"/>target="RFC8554"/>, or BPQS <xref target="BPQS"/> schemes. Unlike many other digital signature techniques, most hash-based signature schemes are stateful, which means that signing necessitates the update and careful tracking of the state of the secret key. Producing multiple signatures using the same secret key state results in loss of security and may ultimately enable signature forgery attacks against that key.</t> <t>Stateful hash-based signatures with long service lifetimes require additional operational complexity comparedwithto other signature types. For example, consider a 20-year root key; there is an expectation that 20 years is longer than the expected lifetime of the hardware that key is stored on,and thereforeso the key will need to be migrated to new hardware at some point. Disaster-recovery scenarios where the primary node fails without warning can be similarly tricky. This requires careful operational and compliance consideration to ensure that no private key state can be reused across the migration or disaster recovery event. One approach for avoiding these issues is to only use statefulHBSHBSs for short-term use cases that do not require horizontal scaling, forexampleexample, signing a batch of firmware images and then retiring the signing key.</t> <t>The SLH-DSA algorithm, which was standardized by NIST, leverages the HORST(hash(Hash toobtain random subsetObtain Random Subset withtrees)Trees) technique and remains the only standardized hash based signature scheme that is stateless, thus avoiding the complexities associated with state management. SLH-DSA is an advancement on SPHINCSwhichthat reduces the signature sizes in SPHINCS and makes it more compact.</t> </section> <section anchor="code-based"> <name>Code-Based Public Key Cryptography</name> <t>This area of cryptography started in the 1970s and80s1980s and was based on the seminal work of McEliece andNiederreiterNiederreiter, which focuses on the study of cryptosystems based on error-correcting codes. Some popularerror correctingerror-correcting codes include Goppa codes (used in McEliece cryptosystems), encoding and decoding syndrome codes used inHamming quasi-cyclic (HQC),HQC, or quasi-cyclic moderate density parity check (QC-MDPC) codes.</t> <t>Examples include all the unbroken NIST Round 4 finalists: Classic McEliece, HQC (selected by NIST for standardization), and Bit Flipping Key Encapsulation (BIKE) <xref target="BIKE"/>.</t> </section> </section> <section anchor="KEMs"> <name>KEMs</name> <t>A Key Encapsulation Mechanism (KEM) is a cryptographic technique used for securely exchanging symmetric key material between two parties over an insecure channel. It is commonly used in hybrid encryptionschemes,schemes where a combination of asymmetric (public key) and symmetric encryption is employed. TheKEMencapsulation operation of a KEM results in a fixed-length symmetric key that can be used with a symmetric algorithm, typically a block cipher, in one of two different ways:</t> <ul spacing="normal"> <li><t>Derive<t>To derive a data encryption key (DEK) to encrypt the data</t> </li> <li><t>Derive<t>To derive a key encryption key (KEK) used to wrap a DEK</t> </li> </ul> <t>These techniques are often referred to as"hybrid public key encryption (HPKE)"the Hybrid Public Key Encryption (HPKE) <xref target="RFC9180"/> mechanism.</t> <t>The term "encapsulation" is chosen intentionally to indicate that KEM algorithms behave differently at the API level from the key agreement or key encipherment/and key transport mechanisms that are in use today. Key agreement schemes imply that both parties contribute apublic / privatepublic-private key pair to the exchange, while key encipherment/and key transport schemes imply that the symmetric key material is chosen by one party and "encrypted" or "wrapped" for the other party. KEMs, on the other hand, behave according to the following API primitives <xref target="PQCAPI"/>:</t> <ul spacing="normal"> <li> <t>def kemKeyGen() -> (pk, sk)</t> </li> <li> <t>def kemEncaps(pk) -> (ss, ct)</t> </li> <li> <t>def kemDecaps(ct, sk) -> ss</t> </li> </ul> <t>where <tt>pk</tt> is the public key, <tt>sk</tt> is the secret key, <tt>ct</tt> is the ciphertext representing an encapsulated key, and <tt>ss</tt> is the shared secret. The following figure illustrates a sample flow of a KEM-based key exchange:</t> <figure anchor="tab-kem-ke"><name>KEM based key exchange</name><name>KEM-Based Key Exchange</name> <artset> <artwork type="svg"><svg xmlns="http://www.w3.org/2000/svg" version="1.1" height="336" width="536" viewBox="0 0 536 336" class="diagram" text-anchor="middle" font-family="monospace" font-size="13px" stroke-linecap="round"> <path d="M 8,272 L 8,304" fill="none" stroke="black"/> <path d="M 24,80 L 24,112" fill="none" stroke="black"/> <path d="M 184,32 L 184,64" fill="none" stroke="black"/> <path d="M 208,80 L 208,112" fill="none" stroke="black"/> <path d="M 208,272 L 208,304" fill="none" stroke="black"/> <path d="M 224,72 L 224,320" fill="none" stroke="black"/> <path d="M 264,32 L 264,64" fill="none" stroke="black"/> <path d="M 280,32 L 280,64" fill="none" stroke="black"/> <path d="M 320,72 L 320,320" fill="none" stroke="black"/> <path d="M 336,176 L 336,208" fill="none" stroke="black"/> <path d="M 360,32 L 360,64" fill="none" stroke="black"/> <path d="M 528,176 L 528,208" fill="none" stroke="black"/> <path d="M 184,32 L 264,32" fill="none" stroke="black"/> <path d="M 280,32 L 360,32" fill="none" stroke="black"/> <path d="M 184,64 L 264,64" fill="none" stroke="black"/> <path d="M 280,64 L 360,64" fill="none" stroke="black"/> <path d="M 24,80 L 208,80" fill="none" stroke="black"/> <path d="M 24,112 L 208,112" fill="none" stroke="black"/> <path d="M 232,160 L 312,160" fill="none" stroke="black"/> <path d="M 336,176 L 528,176" fill="none" stroke="black"/> <path d="M 336,208 L 528,208" fill="none" stroke="black"/> <path d="M 232,256 L 312,256" fill="none" stroke="black"/> <path d="M 8,272 L 208,272" fill="none" stroke="black"/> <path d="M 8,304 L 208,304" fill="none" stroke="black"/> <polygon class="arrowhead" points="320,160 308,154.4 308,165.6" fill="black" transform="rotate(0,312,160)"/> <polygon class="arrowhead" points="240,256 228,250.4 228,261.6" fill="black" transform="rotate(180,232,256)"/> <g class="text"> <text x="220" y="52">Client</text> <text x="316" y="52">Server</text> <text x="48" y="100">pk,</text> <text x="76" y="100">sk</text> <text x="96" y="100">=</text> <text x="152" y="100">kemKeyGen()</text> <text x="216" y="100">-</text> <text x="244" y="148">pk</text> <text x="328" y="196">-</text> <text x="360" y="196">ss,</text> <text x="388" y="196">ct</text> <text x="408" y="196">=</text> <text x="472" y="196">kemEncaps(pk)</text> <text x="292" y="244">ct</text> <text x="28" y="292">ss</text> <text x="48" y="292">=</text> <text x="112" y="292">kemDecaps(ct,</text> <text x="184" y="292">sk)</text> <text x="216" y="292">-</text> </g> </svg> </artwork> <artwork type="ascii-art"><![CDATA[ +---------+ +---------+ | Client | | Server | +---------+ +---------+ +----------------------+ | | | pk, sk = kemKeyGen() |-| | +----------------------+ | | | | | pk | |---------->| | | +-----------------------+ | |-| ss, ct = kemEncaps(pk)| | | +-----------------------+ | | | ct | |<----------| +------------------------+ | | | ss = kemDecaps(ct, sk) |-| | +------------------------+ | | | | ]]></artwork> </artset> </figure> <section anchor="authenticated-key-exchange"> <name>Authenticated Key Exchange</name> <t>Authenticated Key Exchange (AKE) with KEMs where both parties contribute a KEM public key to the overall session key is interactive as described inSection 9.4 of<xref section="9.4" sectionFormat="of" target="RFC9528"/>. However, a single-sided KEM, such as when one peer has a KEM key in a certificate and the other peer wants to encrypt for it (as in S/MIME or OpenPGP email), can be achieved using non-interactive HPKE <xref target="RFC9180"/>. The following figure illustrates theDiffie-Hellman (DH)DH Key exchange:</t> <figure anchor="tab-dh-ake"><name>Diffie-Hellman based<name>DH-Based AKE</name> <artset> <artwork type="svg"><svg xmlns="http://www.w3.org/2000/svg" version="1.1" height="480" width="552" viewBox="0 0 552 480" class="diagram" text-anchor="middle" font-family="monospace" font-size="13px" stroke-linecap="round"> <path d="M 8,320 L 8,368" fill="none" stroke="black"/> <path d="M 24,80 L 24,128" fill="none" stroke="black"/> <path d="M 136,336 L 136,344" fill="none" stroke="black"/> <path d="M 184,32 L 184,64" fill="none" stroke="black"/> <path d="M 216,80 L 216,128" fill="none" stroke="black"/> <path d="M 216,320 L 216,368" fill="none" stroke="black"/> <path d="M 232,72 L 232,464" fill="none" stroke="black"/> <path d="M 264,32 L 264,64" fill="none" stroke="black"/> <path d="M 280,32 L 280,64" fill="none" stroke="black"/> <path d="M 328,72 L 328,464" fill="none" stroke="black"/> <path d="M 344,192 L 344,256" fill="none" stroke="black"/> <path d="M 344,432 L 344,464" fill="none" stroke="black"/> <path d="M 360,32 L 360,64" fill="none" stroke="black"/> <path d="M 544,192 L 544,256" fill="none" stroke="black"/> <path d="M 544,432 L 544,464" fill="none" stroke="black"/> <path d="M 184,32 L 264,32" fill="none" stroke="black"/> <path d="M 280,32 L 360,32" fill="none" stroke="black"/> <path d="M 184,64 L 264,64" fill="none" stroke="black"/> <path d="M 280,64 L 360,64" fill="none" stroke="black"/> <path d="M 24,80 L 216,80" fill="none" stroke="black"/> <path d="M 24,128 L 216,128" fill="none" stroke="black"/> <path d="M 240,176 L 320,176" fill="none" stroke="black"/> <path d="M 344,192 L 544,192" fill="none" stroke="black"/> <path d="M 344,256 L 544,256" fill="none" stroke="black"/> <path d="M 240,304 L 320,304" fill="none" stroke="black"/> <path d="M 8,320 L 216,320" fill="none" stroke="black"/> <path d="M 8,368 L 216,368" fill="none" stroke="black"/> <path d="M 240,416 L 320,416" fill="none" stroke="black"/> <path d="M 344,432 L 544,432" fill="none" stroke="black"/> <path d="M 344,464 L 544,464" fill="none" stroke="black"/> <polygon class="arrowhead" points="328,416 316,410.4 316,421.6" fill="black" transform="rotate(0,320,416)"/> <polygon class="arrowhead" points="328,176 316,170.4 316,181.6" fill="black" transform="rotate(0,320,176)"/> <polygon class="arrowhead" points="248,304 236,298.4 236,309.6" fill="black" transform="rotate(180,240,304)"/> <g class="text"> <text x="220" y="52">Client</text> <text x="316" y="52">Server</text> <text x="72" y="100">Long-term</text> <text x="140" y="100">client</text> <text x="188" y="100">key:</text> <text x="116" y="116">sk1,</text> <text x="152" y="116">pk1</text> <text x="224" y="116">-</text> <text x="256" y="164">pk1</text> <text x="336" y="212">-</text> <text x="392" y="212">Long-term</text> <text x="460" y="212">server</text> <text x="508" y="212">key:</text> <text x="436" y="228">sk2,</text> <text x="472" y="228">pk2</text> <text x="364" y="244">ss</text> <text x="384" y="244">=</text> <text x="436" y="244">KeyEx(pk1,</text> <text x="500" y="244">sk2)</text> <text x="312" y="292">pk2</text> <text x="28" y="340">ss</text> <text x="48" y="340">=</text> <text x="96" y="340">KeyEx(pk2</text> <text x="164" y="340">sk1)</text> <text x="92" y="356">encryptContent(ss)</text> <text x="224" y="356">-</text> <text x="280" y="388">encrypted</text> <text x="288" y="404">content</text> <text x="428" y="452">decryptContent(ss)</text> </g> </svg> </artwork> <artwork type="ascii-art"><![CDATA[ +---------+ +---------+ | Client | | Server | +---------+ +---------+ +-----------------------+ | | | Long-term client key: | | | | sk1, pk1 |-| | +-----------------------+ | | | | | pk1 | |---------->| | | +------------------------+ | |-| Long-term server key: | | | | sk2, pk2 | | | | ss = KeyEx(pk1, sk2) | | | +------------------------+ | | | pk2| |<----------| +-------------------------+ | | | ss = KeyEx(pk2, sk1) | | | | encryptContent(ss) |-| | +-------------------------+ | | | encrypted | | content | |---------->| | | +------------------------+ | | | decryptContent(ss) | | | +------------------------+ ]]></artwork> </artset> </figure><t>What's important to note about<t>In the sample flowaboveabove, it is important to note that the shared secret <tt>ss</tt> is derived using key material from both theClientclient and theServer,server, which classifies it as an AKE. There is another property of a key exchange, called Non-Interactive Key Exchange(NIKE) which(NIKE), that refers to whether the sender can compute the shared secret <tt>ss</tt> and encrypt content without requiring active interaction (an exchange of network messages) with the recipient. <xref target="tab-dh-ake"/> shows aDiffie-HellmanDH keyexchangeexchange, which is anAKE,AKE since both parties are using long-term keyswhichthat can have established trust (for example, via certificates), but it is not aNIKE,NIKE since the client needs to wait for the network interaction to receive the receiver's public key <tt>pk2</tt> before it can compute the shared secret <tt>ss</tt> and begin content encryption. However, a DH key exchange can be an AKE and a NIKE at the same time if the receiver's public key is known to the sender inadvance,advance (see <xref target="tab-dh-ake-nike"/>), and many Internet protocols rely on this property of DH-based key exchanges.</t> <figure anchor="tab-dh-ake-nike"><name>Diffie-Hellman based<name>Simultaneous DH-Based AKE andNIKE simultaneously</name>NIKE</name> <artset> <artwork type="svg"><svg xmlns="http://www.w3.org/2000/svg" version="1.1" height="400" width="536" viewBox="0 0 536 400" class="diagram" text-anchor="middle" font-family="monospace" font-size="13px" stroke-linecap="round"> <path d="M 8,80 L 8,192" fill="none" stroke="black"/> <path d="M 136,160 L 136,168" fill="none" stroke="black"/> <path d="M 168,32 L 168,64" fill="none" stroke="black"/> <path d="M 200,80 L 200,192" fill="none" stroke="black"/> <path d="M 216,72 L 216,368" fill="none" stroke="black"/> <path d="M 248,32 L 248,64" fill="none" stroke="black"/> <path d="M 264,32 L 264,64" fill="none" stroke="black"/> <path d="M 312,72 L 312,368" fill="none" stroke="black"/> <path d="M 328,288 L 328,368" fill="none" stroke="black"/> <path d="M 344,32 L 344,64" fill="none" stroke="black"/> <path d="M 456,336 L 456,344" fill="none" stroke="black"/> <path d="M 528,288 L 528,368" fill="none" stroke="black"/> <path d="M 168,32 L 248,32" fill="none" stroke="black"/> <path d="M 264,32 L 344,32" fill="none" stroke="black"/> <path d="M 168,64 L 248,64" fill="none" stroke="black"/> <path d="M 264,64 L 344,64" fill="none" stroke="black"/> <path d="M 8,80 L 200,80" fill="none" stroke="black"/> <path d="M 8,192 L 200,192" fill="none" stroke="black"/> <path d="M 224,272 L 304,272" fill="none" stroke="black"/> <path d="M 328,288 L 528,288" fill="none" stroke="black"/> <path d="M 328,368 L 528,368" fill="none" stroke="black"/> <polygon class="arrowhead" points="312,272 300,266.4 300,277.6" fill="black" transform="rotate(0,304,272)"/> <g class="text"> <text x="204" y="52">Client</text> <text x="300" y="52">Server</text> <text x="56" y="100">Long-term</text> <text x="124" y="100">client</text> <text x="172" y="100">key:</text> <text x="100" y="116">sk1,</text> <text x="136" y="116">pk1</text> <text x="208" y="116">-</text> <text x="56" y="132">Long-term</text> <text x="124" y="132">server</text> <text x="172" y="132">key:</text> <text x="96" y="148">pk2</text> <text x="28" y="164">ss</text> <text x="48" y="164">=</text> <text x="96" y="164">KeyEx(pk2</text> <text x="164" y="164">sk1)</text> <text x="92" y="180">encryptContent(ss)</text> <text x="208" y="180">-</text> <text x="244" y="228">pk1,</text> <text x="264" y="244">encrypted</text> <text x="272" y="260">content</text> <text x="320" y="308">-</text> <text x="376" y="308">Long-term</text> <text x="444" y="308">server</text> <text x="492" y="308">key:</text> <text x="420" y="324">sk2,</text> <text x="456" y="324">pk2</text> <text x="348" y="340">ss</text> <text x="368" y="340">=</text> <text x="416" y="340">KeyEx(pk1</text> <text x="484" y="340">sk2)</text> <text x="412" y="356">decryptContent(ss)</text> </g> </svg> </artwork> <artwork type="ascii-art"><![CDATA[ +---------+ +---------+ | Client | | Server | +---------+ +---------+ +-----------------------+ | | | Long-term client key: | | | | sk1, pk1 |-| | | Long-term server key: | | | | pk2 | | | | ss = KeyEx(pk2, sk1) | | | | encryptContent(ss) |-| | +-----------------------+ | | | | | pk1, | | encrypted | | content | |---------->| | | +------------------------+ | |-| Long-term server key: | | | | sk2, pk2 | | | | ss = KeyEx(pk1, sk2) | | | | decryptContent(ss) | | | +------------------------+ ]]></artwork> </artset> </figure> <t>The complication with KEMs is that a KEM <tt>Encaps()</tt> is non-deterministic; it involves randomness chosen by the sender of that message. Therefore, in order to perform an AKE, the client must wait for the server to generate the needed randomness and perform <tt>Encaps()</tt> against the client key, which necessarily requires a network round-trip. Therefore, a KEM-based protocol can either be an AKE or a NIKE, but it cannot be both at the same time. Consequently, certain Internet protocols will necessitate a redesign to accommodate this distinction, either by introducing extra networkround-tripsround trips or by making trade-offs in security properties.</t> <figure anchor="tab-kem-ake"><name>KEM based<name>KEM-Based AKE</name> <artset> <artwork type="svg"><svg xmlns="http://www.w3.org/2000/svg" version="1.1" height="480"width="560"width="576" viewBox="0 0560576 480" class="diagram" text-anchor="middle" font-family="monospace" font-size="13px" stroke-linecap="round"> <path d="M8,808,288 L8,112"8,352" fill="none" stroke="black"/> <path d="M8,28824,80 L8,352"24,112" fill="none" stroke="black"/> <path d="M184,32200,32 L184,64"200,64" fill="none" stroke="black"/> <path d="M208,80224,80 L208,112"224,112" fill="none" stroke="black"/> <path d="M208,336224,288 L208,352"224,352" fill="none" stroke="black"/> <path d="M224,72240,72 L224,464"240,464" fill="none" stroke="black"/> <path d="M264,32280,32 L264,64"280,64" fill="none" 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fill="black"transform="rotate(180,232,272)"/>transform="rotate(180,248,272)"/> <g class="text"> <textx="220"x="236" y="52">Client</text> <textx="316"x="332" y="52">Server</text> <textx="36"x="52" y="100">pk1,</text> <textx="72"x="88" y="100">sk1</text> <textx="96"x="112" y="100">=</text> <textx="152"x="168" y="100">kemKeyGen()</text> <textx="216"x="232" y="100">-</text> <textx="240"x="256" y="148">pk1</text> <textx="328"x="344" y="196">-</text> <textx="364"x="380" y="196">ss1,</text> <textx="400"x="416" y="196">ct1</text> <textx="424"x="440" y="196">=</text> <textx="492"x="508" y="196">kemEncaps(pk1)</text> <textx="364"x="380" y="212">pk2,</text> <textx="400"x="416" y="212">sk2</text> <textx="424"x="440" y="212">=</text> <textx="480"x="496" y="212">kemKeyGen()</text> <textx="288"x="304" y="260">ct1,pk2</text> <text x="32" y="308">ss1</text> <text x="56" y="308">=</text> <text x="124" y="308">kemDecaps(ct1,</text> <text x="204" y="308">sk1)</text> <textx="236" y="308">-|</text> <textx="36" y="324">ss2,</text> <text x="72" y="324">ct2</text> <text x="96" y="324">=</text> <text x="164" y="324">kemEncaps(pk2)</text> <text x="232" y="324">-</text> <text x="28" y="340">ss</text> <text x="48" y="340">=</text> <text x="112" y="340">Combiner(ss1,</text> <text x="188" y="340">ss2)</text> <textx="240"x="256" y="388">ct2</text> <textx="328"x="344" y="436">-</text> <textx="360"x="376" y="436">ss2</text> <textx="384"x="400" y="436">=</text> <textx="452"x="468" y="436">kemDecaps(ct2,</text> <textx="532"x="548" y="436">sk2)</text> <textx="356"x="372" y="452">ss</text> <textx="376"x="392" y="452">=</text> <textx="440"x="456" y="452">Combiner(ss1,</text> <textx="516"x="532" y="452">ss2)</text> </g> </svg> </artwork> <artwork type="ascii-art"><![CDATA[ +---------+ +---------+ | Client | | Server | +---------+ +---------+ +------------------------+ | | | pk1, sk1 = kemKeyGen() |-| | +------------------------+ | | | | |pk1 | |---------->| | | +--------------------------+ | |-| ss1, ct1 = kemEncaps(pk1)| | | | pk2, sk2 = kemKeyGen() | | | +--------------------------+ | | | ct1,pk2| |<----------|+------------------------++--------------------------+ | | | ss1 = kemDecaps(ct1,sk1)|-|sk1)| | | | ss2, ct2 =kemEncaps(pk2)|kemEncaps(pk2)|-| | | ss = Combiner(ss1,ss2)|ss2) | |+------------------------+| +--------------------------+ | | | | |ct2 | |---------->| | | +--------------------------+ | |-| ss2 = kemDecaps(ct2, sk2)| | | | ss = Combiner(ss1, ss2) | | | +--------------------------+ ]]></artwork> </artset> </figure><t>Here,<t>In the figure above, <tt>Combiner(ss1, ss2)</tt>, often referred to as a KEMCombiner,combiner, is a cryptographic construction that takes in two shared secrets and returns a single combined shared secret. The simplest combiner is concatenation <tt>ss1 || ss2</tt>, but combiners can vary in complexity depending on the cryptographic properties required. For example, if the combination should preserve IND-CCA2 (see <xreftarget="INDCCA2"/>target="INDCCA2"/>) of eitherinputinput, even if the other is chosen maliciously, then a more complex construct is required. Another consideration for combiner design is the so-called "binding properties" introduced in <xref target="KEEPINGUP"/>, which may require the ciphertexts and recipient public keys to be included in the combiner. KEM combiner security analysis becomes more complicated in hybrid settings where the two KEMs represent different algorithms, for example, where one is ML-KEM and the other is ECDH. For a more thorough discussion of KEM combiners, see <xref target="KEEPINGUP"/>, <xreftarget="I-D.draft-ounsworth-cfrg-kem-combiners"/>,target="I-D.ounsworth-cfrg-kem-combiners"/>, and <xref target="I-D.irtf-cfrg-hybrid-kems"/>.</t> </section> <section anchor="security-properties-of-kems"> <name>Security Properties of KEMs</name> <t>The security properties described in this section (IND-CCA2 and binding) are not an exhaustive list of all possible KEM security considerations. They were selected because they are fundamental to evaluating KEM suitability in protocol design and are commonly discussed in current PQC work.</t> <section anchor="INDCCA2"> <name>IND-CCA2</name> <t>IND-CCA2 (INDistinguishability under adaptive Chosen-Ciphertext Attack) is an advanced security notion for encryption schemes. It ensures the confidentiality of the plaintext and resistance against chosen-ciphertext attacks. An appropriate definition of IND-CCA2 security for KEMs can be found in <xref target="CS01"/> and <xref target="BHK09"/>. ML-KEM <xref target="ML-KEM"/> and Classic McEliece provide IND-CCA2 security.</t> <t>Understanding IND-CCA2 security is essential for individuals involved in designing or implementing cryptographic systems and protocols in order to evaluate the strength of the algorithm, assess its suitability for specific use cases, and ensure that data confidentiality and security requirements are met. Understanding IND-CCA2 security is generally not necessary for developers migrating to using an IETF-vettedkey establishment method (KEM)KEM within a given protocol or flow. IND-CCA2 is a widely accepted security notion for public key encryption mechanisms, making it suitable for a broad range of applications. When an IETF specification defines a new KEM, its security considerations should fully describe the relevant cryptographic properties, including IND-CCA2.</t> </section> <section anchor="binding"> <name>Binding</name> <t>KEMs also have an orthogonal set of properties to consider when designing protocols around them: binding <xref target="KEEPINGUP"/>. This can be "ciphertext binding", "public key binding", "context binding", or any other property that is important to not be substituted between KEM invocations. In general, a KEM is considered to bind a certain value if substitution of that value by an attacker will necessarily result in a different shared secret being derived. As an example, if an attacker can construct two different ciphertextswhichthat will decapsulate to the same sharedsecret; orsecret, can construct a ciphertextwhichthat will decapsulate to the same shared secret under two different public keys, or can substitute whole KEM exchanges from one session into another, then the construction is not ciphertext binding, public key binding, or contextbindingbinding, respectively. Similarly, protocol designers may wish to bind protocol state information such as a transaction ID or nonce so that attempts to replay ciphertexts from one session inside a different session will be blocked at the cryptographic level because the server derives a different shared secret and is thus is unable to decrypt the content.</t> <t>The solution to binding is generally achieved at the protocol design level: It is recommended to avoid using the KEM output shared secret directly without integrating it into an appropriate protocol. While KEM algorithms provide key secrecy, they do not inherently ensure source authenticity, protect against replay attacks, or guarantee freshness. These security properties should be addressed by incorporating the KEM into a protocol that has been analyzed for such protections. Even though modern KEMs such as ML-KEM produce full-entropy shared secrets, it is still advisable for binding reasons to passitthe shared secret through a key derivation function (KDF) and also include all values that you wish to bind;then finallyfinally, you will have a shared secret that is safe to use at the protocol level.</t> </section> </section> <section anchor="hpke"> <name>HPKE</name> <t>Modern cryptography has long used the notion of "hybrid encryption" where an asymmetric algorithm is used to establish akey,key and then a symmetric algorithm is used for bulk content encryption. The previous sections explained important security properties of KEMs, such as IND-CCA2 security and binding, and emphasized that these properties must be supported by proper protocol design. One widely deployed scheme that achieves this isHPKE (HybridHybrid Public KeyEncryption)Encryption (HPKE) <xref target="RFC9180"/>.</t> <t>HPKE(hybrid public key encryption)<xref target="RFC9180"/> works with a combination of KEMs,KDFsKDFs, andAEAD (authenticated encryptionAuthenticated Encryption withadditional data)Associated Data (AEAD) schemes. HPKE includes three authenticated variants, including one that authenticates possession of a pre-shared key and two optional ones that authenticate possession of akey encapsulation mechanism (KEM)KEM private key. HPKE can be extended to support hybrid post-quantum KEM <xref target="I-D.ietf-hpke-pq"/>. ML-KEM does not support the static-ephemeral key exchange that allows HPKE that is based onDH basedDH-based KEMs and its optional authenticated modes as discussed insection 1.5 of<xreftarget="I-D.draft-connolly-cfrg-xwing-kem"/>.</t>section="1.5" sectionFormat="of" target="I-D.connolly-cfrg-xwing-kem"/>.</t> </section> </section> <section anchor="pqc-signatures-1"> <name>PQC Signatures</name> <t>Any digital signature scheme that provides a construction defining security under a post-quantum setting falls under this category of PQC signatures.</t> <section anchor="security-properties-of-pqc-signatures"> <name>Security Properties of PQC Signatures</name> <section anchor="euf-cma-and-suf-cma"> <name>EUF-CMA and SUF-CMA</name> <t>EUF-CMA (existential unforgeability under chosen message attack) <xref target="GMR88"/> is a security notion for digital signature schemes. It guarantees that an adversary, even with access to a signing oracle, cannot forge a valid signature for an arbitrary message. EUF-CMA provides strong protection against forgery attacks, ensuring the integrity and authenticity of digital signatures by preventing unauthorized modifications or fraudulent signatures. ML-DSA, FN-DSA, and SLH-DSA provide EUF-CMA security.</t> <t>SUF-CMA (strong unforgeability under chosen message attack) builds upon EUF-CMA by requiring that an adversary cannot produce a different valid signature for a message that has already been signed by the signing oracle. Like EUF-CMA, SUF-CMA provides robust assurances for digital signature schemes, further enhancing their security posture. ML-DSA, FN-DSA, and SLH-DSA also achieve SUF-CMA security.</t> <t>Understanding EUF-CMA and SUF-CMA security is essential for designing or implementing cryptographic systems in order to ensure the security, reliability, and robustness of digital signature schemes. These notions allow for informeddecision-making,decision making, vulnerability analysis, compliance with standards, and designing systems that provide strong protection against forgery attacks. For developers migrating tousingan IETF-vetted PQC signature scheme within a given protocol or flow, a deep understanding of EUF-CMA and SUF-CMA security may not be necessary, as the schemes vetted by IETF adhere to these stringent security standards.</t> <t>EUF-CMA and SUF-CMA are considered strong security benchmarks for public key signature algorithms, making them suitable for most applications. Authors of IETFspecification authorsspecifications should include all security concerns in the "Security Considerations" section of the relevant RFC and should not assume that implementers are experts in cryptographic theory.</t> </section> </section> <section anchor="sig-scheme"> <name>Details of FN-DSA, ML-DSA, and SLH-DSA</name> <t>ML-DSA <xref target="ML-DSA"/> is a digital signature algorithm based on the hardness of lattice problems over module lattices (i.e., the Module Learning with Errorsproblem (MLWE)).(MLWE) problem). The design of the algorithm is based on the "Fiat-Shamir with Aborts" <xref target="Lyu09"/> framework introduced byLyubashevsky,Lyubashevsky that leverages rejection sampling to render lattice-based Fiat-Shamir (FS) schemes compact and secure. ML-DSA usesuniformly-distributeduniformly distributed random number sampling over small integers to compute coefficients in error vectors, which makes the scheme easier to implement comparedwithto FN-DSA <xreftarget="FN-DSA"/>target="FN-DSA"/>, which uses Gaussian-distributed numbers, necessitating the need to usefloating pointfloating-point arithmetic during signature generation.</t> <t>ML-DSA offers both deterministic and randomized signing and is instantiated with3three parameter sets providing different security levels. Security properties of ML-DSA are discussed inSection 9 of<xreftarget="I-D.ietf-lamps-dilithium-certificates"/>.</t>section="9" sectionFormat="of" target="RFC9881"/>.</t> <t>FN-DSA <xref target="FN-DSA"/> is based on the GPV hash-and-sign lattice-based signature framework introduced by Gentry, Peikert, and Vaikuntanathan, which is a framework that requires a certain class of lattices and a trapdoor sampler technique.</t> <t>The main design principle of FN-DSA is compactness, i.e., it was designed in a way that achieves minimal total memory bandwidth requirement (the sum of the signature size plus the public key size). This is possible due to the compactness of NTRU lattices. FN-DSA also offers very efficient signing and verification procedures. The main potential downsides of FN-DSA refer to the non-triviality of its algorithms and the need forfloating pointfloating-point arithmetic support in order to support Gaussian-distributed random number sampling where the other lattice schemes use the less efficient but easier to supportuniformly-distributeduniformly distributed random number sampling.</t> <t>Implementers of FN-DSA need to be aware that FN-DSA signing is highly susceptible to side-channelattacks,attacks unless constant-time 64-bit floating-point operations are used. This requirement is extremely platform-dependent, as noted in NIST'sreport.</t>report <xref target="NIST"/>.</t> <t>The performance characteristics of ML-DSA and FN-DSA may differ based on the specific implementation and hardware platform. Generally, ML-DSA is known for its relatively fast signature generation, while FN-DSA can provide more efficient signature verification. The choice may depend on whether the application requires more frequent signature generation or signature verification(See(see <xref target="LIBOQS"/>). For further clarity on the sizes and security levels, please refer to the tables in Sections <xreftarget="RecSecurity"/>target="RecSecurity" format="counter"/> and <xreftarget="Comparisons"/>.</t>target="Comparisons" format="counter"/>.</t> <t>SLH-DSA <xref target="SLH-DSA"/> utilizes the concept of stateless hash-based signatures, where each signature is unique and unrelated to any previous signature (as discussed in <xref target="hash-based"/>). This property eliminates the need for maintaining state information during the signing process. SLH-DSA was designed to sign up to2^642<sup>64</sup> messages under a given key pair, and it offers three security levels. The parameters for each of the security levels were chosen to provide 128 bits of security, 192 bits of security, and 256 bits of security. SLH-DSA offers smaller public key sizes, larger signature sizes, slower signature generation, and slower verification when compared to ML-DSA and FN-DSA. SLH-DSA does not introduce a new hardness assumption beyond those inherent to the underlying hash functions. It builds upon established foundations in cryptography, making it a reliable and robust digital signature scheme for a post-quantum world.</t> <t>All of thesealgorithms, ML-DSA,algorithms (ML-DSA, FN-DSA, andSLH-DSASLH-DSA) include two signature modes: pure mode, where the entire content is signed directly, and pre-hash mode, where a digest of the content is signed.</t> </section> <section anchor="details-of-xmss-and-lms"> <name>Details of XMSS and LMS</name> <t>The eXtended Merkle Signature Scheme (XMSS) <xref target="RFC8391"/> and Hierarchical Signature Scheme (HSS) / Leighton-Micali Signature (LMS) <xref target="RFC8554"/> are stateful hash-based signature schemes, where the secret key state changes over time. In both schemes, reusing a secret key state compromises cryptographic security guarantees.</t> <t>XMSS and LMS can be used for signing a potentially large but fixed number ofmessagesmessages, and the number of signing operations depends upon the size of the tree. XMSS and LMS provide cryptographic digital signatures without relying on the conjectured hardness of mathematical problems, instead leveraging the properties of cryptographic hash functions. Multi-tree XMSS and LMS (i.e., XMSS-MT and HSS, respectively) use ahyper-tree basedhyper-tree-based hierarchical approach with a Merkle tree at each level of the hierarchy. <xref target="RFC8391"/> describes both single-tree and multi-tree variants of XMSS, while <xref target="RFC8554"/> describes the Leighton-Micali One-Time Signature (LM-OTS) system as well as the LMS and HSS N-time signature systems. Comparison of XMSS and LMS is discussed inSection 10 of<xref section="10" sectionFormat="of" target="RFC8554"/>.</t> <t>The number of tree layers in multi-tree XMSS and HSS provides a trade-off between signature size on the one side and key generation and signing speed on the other side. Increasing the number of layers reduces key generation time exponentially and signing time linearly at the cost of increasing the signature size linearly. HSS allows for customization of eachsubtreesubtree, whereas XMSS-MT does not, electing instead to use the same structure for each subtree.</t> <t>Due to the complexities described above,theXMSS and LMS are notasuitablereplacementreplacements for traditional signature schemes like RSA or ECDSA. Applications that expect a long lifetime of a signature, like firmware update or secure boot, are typical use cases where those schemes can be successfully applied.</t> <section anchor="lms-key-and-signature-sizes"> <name>LMS Key and Signature Sizes</name> <t>The LMS scheme is characterized by four distinct parameter sets: the underlying hash function (SHA2-256 or SHAKE-256), the length of the digest (24 or 32 bytes), the LMS tree height parameter that controls a maximal number of signatures that the private key can produce, and the width of the Winternitz coefficients (see <xreftarget="RFC8554"/>, section 4.1)section="4.1" sectionFormat="comma" target="RFC8554"/>) that can be used to trade-off signing time for signature size. Parameters can be mixed, providing 80 possible parameterizations of the scheme.</t> <t>The public (PK) and private (SK) key size depends on the length of the digest (M). The signature size depends on the digest, the Winternitz parameter (W), the LMS tree height (H), and the length of the digest. The table below provides key and signature sizes for parameterization with the digest size M=32 of the scheme.</t> <table> <thead> <tr> <th align="left">PK</th> <th align="left">SK</th> <th align="left">W</th> <th align="left">H=5</th> <th align="left">H=10</th> <th align="left">H=15</th> <th align="left">H=20</th> <th align="left">H=25</th> </tr> </thead> <tbody> <tr> <td align="left">56</td> <td align="left">52</td> <td align="left">1</td> <td align="left">8684</td> <td align="left">8844</td> <td align="left">9004</td> <td align="left">9164</td> <td align="left">9324</td> </tr> <tr> <td align="left">56</td> <td align="left">52</td> <td align="left">2</td> <td align="left">4460</td> <td align="left">4620</td> <td align="left">4780</td> <td align="left">4940</td> <td align="left">5100</td> </tr> <tr> <td align="left">56</td> <td align="left">52</td> <td align="left">4</td> <td align="left">2348</td> <td align="left">2508</td> <td align="left">2668</td> <td align="left">2828</td> <td align="left">2988</td> </tr> <tr> <td align="left">56</td> <td align="left">52</td> <td align="left">8</td> <td align="left">1292</td> <td align="left">1452</td> <td align="left">1612</td> <td align="left">1772</td> <td align="left">1932</td> </tr> </tbody> </table> </section> </section> <section anchor="hash-then-sign"> <name>Hash-then-Sign</name> <t>Within the hash-then-sign paradigm, the message is hashed before signing it. By pre-hashing, the onus of resistance to existential forgeries becomes heavily reliant on the collision-resistance of the hash function in use. The hash-then-sign paradigm has the ability to improve application performance by reducing the size of signed messages that need to be transmitted between application and cryptographicmodule,module and making the signature size predictable and manageable. As a corollary, hashing remains mandatory even for short messages and assigns a further computational requirement onto the verifier. This makes the performance of hash-then-sign schemes more consistent, but not necessarily more efficient.</t> <t>Using a hash function to produce a fixed-size digest of a message ensures that the signature is compatible with a wide range of systems and protocols, regardless of the specific message size or format. Crucially for hardware security modules,Hash-then-Signhash-then-sign also significantly reduces the amount of data that needs to be transmitted and processed by a Hardware Security Module (HSM). Consider scenarios such as a networked HSM located in a different data center from the calling application or a smart card connected over a USB interface. In these cases, streaming a message that is megabytes or gigabytes long can result in notable network latency, on-device signing delays, or even depletion of available on-device memory.</t> <t>Note that the vast majority of Internet protocols that sign large messages already perform some form of content hashing at the protocol level, so this tends to be more of a concern with proprietary cryptographicprotocols,protocols and protocols from non-IETF standards bodies. Protocols like TLS 1.3 and DNSSEC use theHash-then-Signhash-then-sign paradigm. In TLS 1.3 <xref target="RFC8446"/> CertificateVerify messages, the content that is covered under the signature includes the transcript hash output(Section 4.4.1 of <xref target="RFC8446"/>),(<xref section="4.4.1" sectionFormat="of" target="RFC8446"/>) while DNSSEC <xref target="RFC4034"/> uses it to provide origin authentication and integrity assurance services for DNS data. Similarly, the Cryptographic Message Syntax (CMS) <xref target="RFC5652"/> includes a mandatory message digest step before invoking the signature algorithm.</t> <t>In the case of ML-DSA, it internally incorporates the necessary hash operations as part of its signing algorithm. ML-DSA directly takes the original message, applies a hash function internally, and then uses the resulting hash value for the signature generation process. In the case of SLH-DSA, it internally performs randomized message compression using a keyed hash function that can process arbitrary length messages. In the case of FN-DSA, the SHAKE-256 hash function is used as part of the signature process to derive a digest of the message being signed.</t> <t>Therefore, ML-DSA, FN-DSA, and SLH-DSA offer enhanced security over the traditionalHash-then-Signhash-then-sign paradigmbecausebecause, by incorporating dynamic key material into the message digest, a pre-computed hash collision on the message to be signed no longer yields a signature forgery. Applications requiring the performance and bandwidth benefits ofHash-then-Signhash-then-sign may still pre-hash at the protocol level prior to invoking ML-DSA, FN-DSA, or SLH-DSA, but protocol designers should be aware that doing sore-introducesreintroduces the weakness that hash collisions directly yield signature forgeries. Signing the full un-digested message is recommended where applications can tolerate it.</t> </section> </section> <section anchor="RecSecurity"> <name>NIST Recommendations for Security/and PerformanceTradeoffs</name>Trade-offs</name> <t>This information is are-printreprint of information provided in the NIST PQC project <xref target="NIST"/> as of the time this document is published.The Table 2<xref target="security-levels-table"/> denotes the five security levels provided by NIST for PQC algorithms. Neither NIST nor the IETFmakemakes any specific recommendations about which security level to use. In general, protocols will include algorithm choices at multiple levels so that users can choose the level appropriate to their policies and data classification, similar to how organizations today choose which size of RSA key to use. The security levels are defined as requiring computational resources comparable to or greater than an attack on AES (128,192192, and 256) and SHA2/SHA3 algorithms, i.e., exhaustive key recovery for AES and optimal collision search for SHA2/SHA3.</t><table><table anchor="security-levels-table"> <thead> <tr> <th align="left">PQ Security Level</th> <th align="left">AES/SHA(2/3) hardness</th> <th align="left">PQC Algorithm</th> </tr> </thead> <tbody> <tr> <td align="left">1</td> <td align="left">AES-128 (exhaustive key recovery)</td> <td align="left">ML-KEM-512, FN-DSA-512, SLH-DSA-SHA2/SHAKE-128f/s</td> </tr> <tr> <td align="left">2</td> <td align="left">SHA-256/SHA3-256 (collision search)</td> <td align="left">ML-DSA-44</td> </tr> <tr> <td align="left">3</td> <td align="left">AES-192 (exhaustive key recovery)</td> <td align="left">ML-KEM-768, ML-DSA-65, SLH-DSA-SHA2/SHAKE-192f/s</td> </tr> <tr> <td align="left">4</td> <td align="left">SHA-384/SHA3-384 (collision search)</td> <td align="left">No algorithm tested at this level</td> </tr> <tr> <td align="left">5</td> <td align="left">AES-256 (exhaustive key recovery)</td> <td align="left">ML-KEM-1024, FN-DSA-1024, ML-DSA-87, SLH-DSA-SHA2/SHAKE-256f/s</td> </tr> </tbody> </table> <t>The SLH-DSA-x-yf/s "f/s" in the above table denotes whether SLH-DSA is using SHAKE or SHA-2 as an underlying hash function "x" and whether it is the fast (f) or small (s) version for "y" bit AES security level. Refer to <xreftarget="I-D.ietf-lamps-cms-sphincs-plus"/>target="RFC9814"/> for further details on SLH-DSA algorithms.</t> <t>The following table compares the signature sizes for different SLH-DSA algorithm categories at equivalent securitylevels,levels using the "simple" version. The categories include"(f)""f" for fast signaturegeneration,generation and"(s)""s" for smaller signature size and faster verification, although with slower signature generation. Both SHA-256 and SHAKE-256 parameterizations produce the same signature sizes and are therefore included together in the table.</t> <table> <thead> <tr> <th align="left">PQ Security Level</th> <th align="left">Algorithm</th> <th align="left">Public key size (in bytes)</th> <th align="left">Private key size (in bytes)</th> <th align="left">Signature size (in bytes)</th> </tr> </thead> <tbody> <tr> <td align="left">1</td> <td align="left">SLH-DSA-{SHA2,SHAKE}-128f</td> <td align="left">32</td> <td align="left">64</td> <td align="left">17088</td> </tr> <tr> <td align="left">1</td> <td align="left">SLH-DSA-{SHA2,SHAKE}-128s</td> <td align="left">32</td> <td align="left">64</td> <td align="left">7856</td> </tr> <tr> <td align="left">3</td> <td align="left">SLH-DSA-{SHA2,SHAKE}-192f</td> <td align="left">48</td> <td align="left">96</td> <td align="left">35664</td> </tr> <tr> <td align="left">3</td> <td align="left">SLH-DSA-{SHA2,SHAKE}-192s</td> <td align="left">48</td> <td align="left">96</td> <td align="left">16224</td> </tr> <tr> <td align="left">5</td> <td align="left">SLH-DSA-{SHA2,SHAKE}-256f</td> <td align="left">64</td> <td align="left">128</td> <td align="left">49856</td> </tr> <tr> <td align="left">5</td> <td align="left">SLH-DSA-{SHA2,SHAKE}-256s</td> <td align="left">64</td> <td align="left">128</td> <td align="left">29792</td> </tr> </tbody> </table> <t>The following table illustrates the impact of performance on different security levels in terms of private key sizes, public key sizes, and ciphertext/signature sizes.</t> <table> <thead> <tr> <th align="left">PQ Security Level</th> <th align="left">Algorithm</th> <th align="left">Public key size (in bytes)</th> <th align="left">Private key size (in bytes)</th> <th align="left">Ciphertext/signature size (in bytes)</th> </tr> </thead> <tbody> <tr> <td align="left">1</td> <td align="left">ML-KEM-512</td> <td align="left">800</td> <td align="left">1632</td> <td align="left">768</td> </tr> <tr> <td align="left">1</td> <td align="left">FN-DSA-512</td> <td align="left">897</td> <td align="left">1281</td> <td align="left">666</td> </tr> <tr> <td align="left">2</td> <td align="left">ML-DSA-44</td> <td align="left">1312</td> <td align="left">2560</td> <td align="left">2420</td> </tr> <tr> <td align="left">3</td> <td align="left">ML-KEM-768</td> <td align="left">1184</td> <td align="left">2400</td> <td align="left">1088</td> </tr> <tr> <td align="left">3</td> <td align="left">ML-DSA-65</td> <td align="left">1952</td> <td align="left">4032</td> <td align="left">3309</td> </tr> <tr> <td align="left">5</td> <td align="left">FN-DSA-1024</td> <td align="left">1793</td> <td align="left">2305</td> <td align="left">1280</td> </tr> <tr> <td align="left">5</td> <td align="left">ML-KEM-1024</td> <td align="left">1568</td> <td align="left">3168</td> <td align="left">1588</td> </tr> <tr> <td align="left">5</td> <td align="left">ML-DSA-87</td> <td align="left">2592</td> <td align="left">4896</td> <td align="left">4627</td> </tr> </tbody> </table> </section> <section anchor="Comparisons"> <name>Comparing PQC KEMs/Signaturesvs.and TraditionalKEMs (KEXs)/Signatures</name>KEMs/Signatures</name> <t>This section provides two tables for comparison of different KEMs andsignaturessignatures, respectively, in the traditional and post-quantum scenarios. These tables focus on the secret key sizes, public key sizes, and ciphertext/signature sizes for the PQC algorithms and their traditional counterparts of similar security levels.</t> <t>The first table compares traditionalvs.and PQC KEMs in terms of security, public and private key sizes, and ciphertext sizes.</t> <table> <thead> <tr> <th align="left">PQ Security Level</th> <th align="left">Algorithm</th> <th align="left">Public key size (in bytes)</th> <th align="left">Private key size (in bytes)</th> <th align="left">Ciphertext size (in bytes)</th> </tr> </thead> <tbody> <tr> <td align="left">Traditional</td> <td align="left">P256_HKDF_SHA-256</td> <td align="left">65</td> <td align="left">32</td> <td align="left">65</td> </tr> <tr> <td align="left">Traditional</td> <td align="left">P521_HKDF_SHA-512</td> <td align="left">133</td> <td align="left">66</td> <td align="left">133</td> </tr> <tr> <td align="left">Traditional</td> <td align="left">X25519_HKDF_SHA-256</td> <td align="left">32</td> <td align="left">32</td> <td align="left">32</td> </tr> <tr> <td align="left">1</td> <td align="left">ML-KEM-512</td> <td align="left">800</td> <td align="left">1632</td> <td align="left">768</td> </tr> <tr> <td align="left">3</td> <td align="left">ML-KEM-768</td> <td align="left">1184</td> <td align="left">2400</td> <td align="left">1088</td> </tr> <tr> <td align="left">5</td> <td align="left">ML-KEM-1024</td> <td align="left">1568</td> <td align="left">3168</td> <td align="left">1568</td> </tr> </tbody> </table> <t>The next table compares traditionalvs.and PQC signature schemes in terms of security, public, private key sizes, and signature sizes.</t> <table> <thead> <tr> <th align="left">PQ Security Level</th> <th align="left">Algorithm</th> <th align="left">Public key size (in bytes)</th> <th align="left">Private key size (in bytes)</th> <th align="left">Signature size (in bytes)</th> </tr> </thead> <tbody> <tr> <td align="left">Traditional</td> <td align="left">RSA2048</td> <td align="left">256</td> <td align="left">256</td> <td align="left">256</td> </tr> <tr> <td align="left">Traditional</td> <td align="left">ECDSA-P256</td> <td align="left">64</td> <td align="left">32</td> <td align="left">64</td> </tr> <tr> <td align="left">1</td> <td align="left">FN-DSA-512</td> <td align="left">897</td> <td align="left">1281</td> <td align="left">666</td> </tr> <tr> <td align="left">2</td> <td align="left">ML-DSA-44</td> <td align="left">1312</td> <td align="left">2560</td> <td align="left">2420</td> </tr> <tr> <td align="left">3</td> <td align="left">ML-DSA-65</td> <td align="left">1952</td> <td align="left">4032</td> <td align="left">3309</td> </tr> <tr> <td align="left">5</td> <td align="left">FN-DSA-1024</td> <td align="left">1793</td> <td align="left">2305</td> <td align="left">1280</td> </tr> <tr> <td align="left">5</td> <td align="left">ML-DSA-87</td> <td align="left">2592</td> <td align="left">4896</td> <td align="left">4627</td> </tr> </tbody> </table> <t>As is clear from the above table, PQC KEMs and signature schemes typically have significantly larger keys and ciphertexts/signatures than their traditional counterparts. These increased key and signatures sizes could introduce problems in protocols. As an example,IKEv2the Internet Key Exchange Protocol Version 2 (IKEv2) uses UDP as the transport protocol for its messages. One challenge with integrating a PQC KEM into IKEv2 is that IKE fragmentation cannot be utilized in the initial IKE_SA_INIT exchange. To address this issue, <xref target="RFC9242"/> introduces a solution by defining a new exchange called the "IntermediateExchange"Exchange", which can be fragmented using the IKE fragmentation mechanism. <xref target="RFC9370"/> then uses this Intermediate Exchange to carry out the PQC key exchange after the initial IKEv2 exchange and before the IKE_AUTH exchange. Another example from Section 6.3.3 of <xref target="SP-1800-38C"/>section 6.3.3shows that increased key and signature sizes cause protocol key exchange messages to span more network packets,therefore itwhich results in a higher total loss probability per packet. In lossy network conditions, this may increase the latency of the key exchange.</t> </section> <section anchor="PQT"> <name>Post-Quantum and Traditional (PQ/T) Hybrid Schemes</name> <t>The migration to PQC is unique in the history of modern digital cryptography in that neither the traditional algorithms nor the post-quantum algorithms are fully trusted to protect data for the required lifetimes. The traditional algorithms, such as RSA and ECDH, will fall to quantum cryptanalysis, while the post-quantum algorithms face uncertainty about the underlying mathematics, compliance issues, unknown vulnerabilities, and hardware and software implementations that have not had sufficient maturing time to rule out traditional cryptanalytic attacks and implementation bugs.</t> <t>During the transition from traditional to post-quantum algorithms, there may be a desire or a requirement for protocols that use both algorithm types. <xreftarget="I-D.ietf-pquip-pqt-hybrid-terminology"/>target="RFC9794"/> defines the terminology forthe post-quantum and traditional (PQ/T)PQ/T hybrid schemes.</t> <section anchor="pqt-hybrid-confidentiality"> <name>PQ/T Hybrid Confidentiality</name> <t>The PQ/T Hybrid Confidentiality property can be used to mitigate both "harvest now, decrypt now" and HNDL attacks described in <xref target="timeline"/>. If the PQ portion were to have a flaw, the traditional (T) algorithm, which is secure againsttoday’stoday's attackers, prevents immediate decryption ("harvest now, decrypt now"). If the T algorithm is broken in the future by CRQCs, the PQ portion, assuming it remains secure, prevents later decryption("harvest now, decrypt later").(i.e., HNDL). A hybrid construction therefore provides confidentiality as long as at least one component remains secure. Two types of hybrid key agreement schemes are discussed below.</t><ul spacing="normal"> <li> <t>Concatenated<dl> <dt>Concatenated hybrid key agreementscheme: Thescheme:</dt> <dd> <t>The final shared secret that will be used as an input of the key derivation function is the result of the concatenation of the secrets established with each key agreement scheme. For example, in <xref target="I-D.ietf-tls-hybrid-design"/>, the client uses the TLS supported groups extension to advertise support for a PQ/T hybrid scheme, and the server can select this group if it supports the scheme. The hybrid-aware client and server establish a hybrid secret by concatenating the two shared secrets, which is used as the shared secret in the existing TLS 1.3 key schedule.</t></li> <li> <t>Cascaded</dd> <dt>Cascaded hybrid key agreementscheme: Thescheme:</dt> <dd> <t>The final shared secret is computed by applying as many iterations of the key derivation function as the number of key agreement schemes composing the hybrid key agreement scheme. For example, <xref target="RFC9370"/> extendsthe Internet Key Exchange Protocol Version 2 (IKEv2)IKEv2 to allow one or more PQC algorithms in addition to the traditional algorithm to derive the final IKESASecurity Association (SA) keys using the cascade method as explained inSection 2.2.2 of<xref section="2.2.2" sectionFormat="of" target="RFC9370"/>.</t></li> </ul></dd> </dl> <t>Various instantiations of these two types of hybrid key agreement schemes have been explored. One must be careful when selecting which hybrid scheme to use. The chosen scheme for protocols like TLS 1.3 <xref target="I-D.ietf-tls-hybrid-design"/> has IND-CCA2 robustness. That is, IND-CCA2 security is guaranteed for the scheme as long as at least one of the component algorithms is IND-CCA2 secure.</t> </section> <section anchor="pqt-hybrid-authentication"> <name>PQ/T Hybrid Authentication</name> <t>The PQ/T hybrid authentication property provides resilience against catastrophic breaks or unforeseen vulnerabilities in PQC algorithms, allowing systems additional time to stabilize before migrating fully to pure PQ deployments.</t> <t>This property ensures authentication using a PQ/T hybridscheme,scheme as long as at least one component algorithm remains secure. For example, a PQ/T hybrid certificate <xref target="I-D.ietf-lamps-pq-composite-sigs"/> can be employed to facilitate a PQ/T hybrid authentication protocol. However, a PQ/T hybrid authentication protocol does not need to use a PQ/T hybrid certificate; separate certificates could be used for individual component algorithms <xreftarget="I-D.ietf-lamps-cert-binding-for-multi-auth"/>.target="RFC9763"/>. When separate certificates are used, it may be possible for attackers to take them apart or put them together in unexpected ways, including enabling cross-protocol attacks. The exact risks this presents are highly dependent on the protocol and use case, so a full security analysis is needed. Best practices for ensuring that pairs of certificates are only used as intended are discussed in more detail in Sections <xreftarget="COMPOSITE"/>target="COMPOSITE" format="counter"/> and <xreftarget="REUSE"/>target="REUSE" format="counter"/> of this document.</t> <t>The frequency and duration of system upgrades and the time when CRQCs will become widely available need to be weighed to determine whether and when to support the PQ/T Hybrid Authentication property.</t> </section> <section anchor="hybrid-cryptographic-algorithm-combinations-considerations-and-approaches"> <name>Hybrid Cryptographic Algorithm Combinations: Considerations and Approaches</name> <section anchor="hybrid-cryptographic-combinations"> <name>Hybrid Cryptographic Combinations</name> <t>It is also possible to use more than two algorithms together in a hybrid scheme, with various methods for combining them. For post-quantum transition purposes, the combination of a post-quantum algorithm with a traditional algorithm is the most straightforward and recommended. The use of multiple post-quantum algorithms with different mathematical bases has also been considered. Combining algorithms in a way that requires both to be used together ensures stronger security, while combinations that do not require both will sacrifice security but offer other benefits like backwards compatibility and crypto agility. Including a traditional key alongside a post-quantum key often has minimal bandwidth impact.</t> </section> <section anchor="COMPOSITE"> <name>Composite Keys in Hybrid Schemes</name> <t>When combining keys in an "and" mode, it may make more sense to consider them to be a single compositekey,key instead of two keys. This generally requires fewer changes to various components of PKI ecosystems, many of which are not prepared to deal with two keys or dual signatures. To those protocol- or application-layer parsers, a "composite" algorithm composed of two "component" algorithms is simply a new algorithm, and support for adding new algorithms generally already exists. Treating multiple "component" keys as a single "composite" key also has securityadvantagesadvantages, such as preventing cross-protocol reuse of the individual component keys and guarantees about revoking or retiring all component keys together at the same time, especially if the composite is treated as a single object all the way down into the cryptographic module.</t> <t>All that needs to be done is to standardize the formats of how the two keys from the two algorithms are combined into a single datastructure,structure and how the two resulting signatures or KEMs are combined into a single signature or KEM. The answer can be as simple asconcatenation,concatenation if the lengths are fixed or easily determined. At the time this document is published, security research is ongoing as to the security properties of concatenation-based composite signatures and KEMsvs.versus more sophisticated signature and KEMcombiners,combiners andin whichprotocol contexts in which those simpler combiners are sufficient.</t> <t>One last consideration is the specific pairs of algorithms that can be combined. A recent trend in protocols is to only allow a small number of "known good" configurations that make sense, often referred to in cryptography as a "ciphersuite", instead of allowing arbitrary combinations of individual configuration choices that may interact in dangerous ways. The current consensus is that the same approach should be followed for combining cryptographicalgorithms,algorithms and that "known good" pairs should be explicitly listed ("explicitcomposite"),composite") instead of just allowing arbitrary combinations of any two cryptographic algorithms ("generic composite").</t> <t>The same considerations apply when using multiple certificates to transport a pair of related keys for the same subject. Exactly how two certificates should be managed in order to avoid some of the pitfalls mentioned above is still an active area of investigation. Using two certificates keeps the certificate tooling simple and straightforward, but in theendend, this simply movestheproblems (i.e., problems withrequiringthe requirement that bothcerts are intended tocertificates be used as a pair,must producethat two signatureswhichthat must be carried separately, and that bothmust validate,validate) to the certificate management layer, where addressing these concerns in a robust way can be difficult.</t> <t>At least one scheme has been proposed that allows the pair of certificates to exist as a single certificate when being issued andmanaged,managed but dynamically split into individual certificates when needed(<xref target="I-D.draft-bonnell-lamps-chameleon-certs"/>).</t>(see <xref target="I-D.bonnell-lamps-chameleon-certs"/>).</t> </section> <section anchor="REUSE"> <name>Key Reuse in Hybrid Schemes</name> <t>An important security note, particularly when using hybrid signature keys, but also to a lesser extent hybrid KEM keys, is key reuse. In traditional cryptography, problems can occur with so-called "cross-protocol attacks" when the same key can be used for multiple protocols; forexampleexample, signing TLS handshakes and signing S/MIME emails. While it is notbest-practicebest practice to reuse keys within the same protocol,for examplee.g., using the same key for multiple S/MIME certificates for the same user, it is not generally catastrophic for security. However, key reuse becomes a large security problem withinhybrids.</t>hybrid schemes.</t> <t>Consider an {RSA, ML-DSA} hybrid key where the RSA key also appears within a single-algorithm certificate. In this case, an attacker could perform a "stripping attack" where they take some piece of data signed with the {RSA, ML-DSA} key, remove the ML-DSAsignaturesignature, and present the data as if it was intended for the RSA only certificate. This leads to a set of security definitions called "non-separability properties", which refers to how well the signature scheme resists various complexities ofdowngrade / strippingdowngrade/stripping attacks <xreftarget="I-D.draft-ietf-pquip-hybrid-signature-spectrums"/>.target="I-D.ietf-pquip-hybrid-signature-spectrums"/>. Therefore, it is recommended that implementers either reuse the entire hybrid key as awhole,whole or perform fresh key generation of all component keys per usage, and must not take an existing key and reuse it as a component of ahybrid.</t>hybrid key.</t> </section> <section anchor="future-directions-and-ongoing-research"> <name>Future Directions and Ongoing Research</name> <t>Many aspects of hybrid cryptography are still under investigation. The LAMPSWGWorking Group at IETF is actively exploring the security properties of these combinations, and future standards will reflect the evolving consensus on these issues.</t> </section> </section> </section> <section anchor="impact-on-constrained-devices-and-networks"> <name>Impact on Constrained Devices and Networks</name> <t>PQC algorithms generally have larger keys, ciphertext, and signature sizes than traditional public key algorithms. This has particular impact on constrained devices that operate with limited data rates. In the IoT space, these constraints have historically driven significant optimization efforts in the IETF (e.g.,LAKE, CoRE)in the LAKE and CoRE Working Groups) to adapt security protocols to resource-constrained environments.</t> <t>As the transition to PQC progresses, these environments will face similar challenges. Larger message sizes can increase handshake latency, raise energy consumption, and require fragmentation logic. Work is ongoing in the IETF to study how PQC can be deployed in constrained devices (see <xref target="I-D.ietf-pquip-pqc-hsm-constrained"/>).</t> </section> <section anchor="security-considerations"> <name>Security Considerations</name> <section anchor="cryptanalysis"> <name>Cryptanalysis</name> <t>Traditional cryptanalysis exploits weaknesses in algorithm design, mathematical vulnerabilities, or implementationflaws,flaws that are exploitable with classical(i.e.(i.e., non-quantum) hardware, whereas quantum cryptanalysis harnesses the power of CRQCs to solve specific mathematical problems more efficiently.AnotherQuantum side-channel attacks are another form of quantumcryptanalysis is "quantum side-channel" attacks.cryptanalysis. In such attacks, a device under threat is directly connected to a quantum computer, which then injects entangled or superimposed data streams to exploit hardware that lacks protection against quantumside-channels.side channels. Both pose threats to the security of cryptographic algorithms, including those used in PQC.DevelopingIt is crucial to develop andadoptingadopt new cryptographic algorithms resilient against these threatsis crucial for ensuringto ensure long-term security in the face of advancing cryptanalysis techniques.</t> <t>Recent attacks on the side-channel implementations using deeplearning basedlearning-based power analysis have also shown that one needs to be cautious while implementing the required PQC algorithms in hardware. Two of the most recent works include one attack on ML-KEM <xref target="KyberSide"/> and one attack on Saber <xref target="SaberSide"/>. An evolving threat landscape points to the fact thatlattice basedlattice-based cryptography is indeed more vulnerable to side-channel attacks as in <xreftarget="SideCh"/>,target="SideCh"/> and <xref target="LatticeSide"/>. Consequently,there weresome mitigation techniques forside channelside-channel attacksthathave beenproposed as inproposed; see <xref target="Mitigate1"/>, <xref target="Mitigate2"/>, and <xref target="Mitigate3"/>.</t> </section> <section anchor="cryptographic-agility"> <name>Cryptographic Agility</name> <t>Cryptographic agility is recommended for both traditional and quantum cryptanalysis as it enables organizations to adapt to emerging threats, adopt stronger algorithms, comply with standards, and plan for long-term security in the face of evolving cryptanalytic techniques and the advent of CRQCs.</t> <t>Several PQC schemes are available that need to be tested; cryptography experts around the world are pushing for the best possible solutions, and the first standards that will ease the introduction of PQC are being prepared.ItThis is of paramount importance and is a call for imminent action for organizations, bodies, and enterprises to start evaluating their cryptographic agility, assess the complexity of implementing PQC into their products, processes, and systems, and develop a migration plan that achieves their security goals to the best possible extent.</t> <t>An important and often overlooked step in achieving cryptographic agility is maintaining a cryptographic inventory. Modern software stacks incorporate cryptography in numerous places, making it challenging to identify all instances. Therefore, cryptographic agility and inventory management take two majorforms:forms. First, application developers responsible for software maintenance should actively search for instances of hard-coded cryptographic algorithms within applications. When possible, they should design the choice of algorithm to be dynamic, based on application configuration. Second, administrators, policy officers, and compliance teams should take note of any instances where an application exposes cryptographic configurations. These instances should be managedeitherthrough either organization-wide written cryptographic policies or automated cryptographic policy systems.</t> <t>Numerous commercial solutions are available forbothdetecting hard-coded cryptographic algorithms in source code and compiled binaries, as well as providing cryptographic policy management control planes for enterprise and production environments.</t> </section> <section anchor="jurisdictional-fragmentation"> <name>Jurisdictional Fragmentation</name> <t>Another potential application ofhybridshybrid schemes bears mentioning, even though it is not directlyPQC-related. That isrelated to PQC: using hybrids to navigate inter-jurisdictional cryptographic connections. Traditional cryptography is already fragmented byjurisdiction: considerjurisdiction. Consider that while most jurisdictions supportElliptic Curve Diffie-Hellman,ECDH, those in the United States will prefer the NIST curves while those in Germany will prefer the Brainpool curves. China, Russia, and other jurisdictions have their own national cryptography standards. This situation of fragmented global cryptography standards is unlikely to improve with PQC. If "and" modehybridshybrid schemes become standardized for the reasons mentioned above, then one could imagine leveraging them to create"ciphersuites"ciphersuites in which a single cryptographic operation simultaneously satisfies the cryptographic requirements of both endpoints.</t> </section> <sectionanchor="hybrid-key-exchange-and-signatures-bridging-the-gap-between-post-quantum-and-traditional-cryptography">anchor="hybrid-key-exchange-and-signatures-bridging-the-gap-between-pqt-cryptography"> <name>Hybrid Key Exchange and Signatures: Bridging the Gap BetweenPost-Quantum and TraditionalPQ/T Cryptography</name> <t>Post-quantum algorithms selected for standardization are relatively new andtheyhave not been subject to the same depth of study as traditional algorithms. PQC implementations will also be new and therefore more likely to contain implementation bugs than the battle-tested crypto implementations that are relied on today. In addition, certain deployments may need to retain traditional algorithms due to regulatory constraints,for examplee.g., FIPS <xref target="SP-800-56C"/> orPCIPayment Card Industry (PCI) compliance <xref target="PCI"/>. Hybrid key exchange is recommended to enhance security against the"harvest now, decrypt later"HNDL attack. Additionally, hybrid signatures provide for time to react in the case of the announcement of a devastating attack against any one algorithm, while not fully abandoning traditional cryptosystems.</t> <t>Hybrid key exchange performs both a classical and a post-quantum key exchange in parallel. It provides security redundancy against potential weaknesses in PQC algorithms, allows for a gradual transition of trust in PQC algorithms, and, in backward-compatible designs, enables gradual adoption without breaking compatibility with existing systems. For instance, in TLS 1.3, a hybrid key exchange can combine a widely supported classical algorithm, such as X25519, with a post-quantum algorithm like ML-KEM. This allows legacy clients to continue using the classical algorithm while enabling upgraded clients to proceed with hybrid key exchange. In contrast, overhead-spreading hybrid designs focus on reducing the PQ overhead. For example, approaches like those described in <xreftarget="I-D.hale-mls-combiner"/>target="I-D.ietf-mls-combiner"/> amortize PQ costs by selectively applying PQ updates in key exchange processes, allowing systems to balance security and efficiency. This strategy ensures a post-quantum secure channel while keeping the overhead manageable, making it particularly suitable for constrained environments.</t> <t>While some hybrid key exchange options introduce additional computational and bandwidth overhead, the impact of traditional key exchange algorithms (e.g., key size) is typically small, helping to keep the overall increase in resource usage manageable for most systems. In highly constrained environments, however, those hybrid key exchange protocols may be impractical due to their higher resource requirements compared to pure post-quantum or traditional key exchange approaches. However, some hybrid key exchange designs distribute the PQC overhead, making them more suitable for constrained environments. The choice of hybrid key exchange design depends on the specific system requirements and use case, so the appropriate approach may vary.</t> </section> <section anchor="caution-ciphertext-commitment-in-kem-vs-dh"> <name>Caution: CiphertextcommitmentCommitment in KEM vs. DH</name> <t>The ciphertext generated by a KEM is not necessarily directly linked to the shared secret it produces. KEMs allow for multiple ciphertexts to encapsulate the same shared secret, which enables flexibility in key management without enforcing a strict one-to-one correspondence between ciphertexts and shared secrets. This allows for secret reuse across different recipients, sessions, or operational contexts without the need for new secrets for each use, simplifying key distribution and reducing computational overhead. In contrast, cryptographic schemes like Diffie-Hellman inherently link the public key to the derived shared secret, meaning any change in the public key results in a different shared secret.</t> </section> </section> <section anchor="iana-considerations"> <name>IANA Considerations</name> <t>This document has no IANAconsiderations.</t>actions.</t> </section> <sectionanchor="further-reading-resources">anchor="further-reading-and-resources"> <name>Further Reading&and Resources</name> <t>A good book on modern cryptography isSerious"Serious Cryptography, 2ndEdition,Edition" by Jean-PhilippeAumasson, ISBN 9781718503847.</t>Aumasson <xref target="Serious-Crypt"/>.</t> <t>The Open Quantum Safe (OQS) Project <xref target="OQS"/> is an open-source project that aims to support the transition to quantum-resistant cryptography.</t> <t>The IETF's PQUIP Working Group <xref target="PQUIP-WG"/> maintains a list of PQC-related protocol work within the IETF.</t> </section> </middle> <back> <displayreference target="I-D.bonnell-lamps-chameleon-certs" to="ENC-PAIR-CERTS"/> <displayreference target="I-D.connolly-cfrg-xwing-kem" to="X-WING"/> <displayreference target="I-D.ietf-mls-combiner" to="PQ-MLS"/> <displayreference target="I-D.ietf-hpke-pq" to="PQ-HPKE"/> <displayreference target="I-D.ietf-lamps-pq-composite-sigs" to="ML-DSA-X.509"/> <displayreference target="I-D.ietf-pquip-hybrid-signature-spectrums" to="HYBRID-SIG-SPECT"/> <displayreference target="I-D.ietf-pquip-pqc-hsm-constrained" to="CONSTRAIN-DEV-PCQ"/> <displayreference target="I-D.ietf-tls-hybrid-design" to="TLS-HYB-KEY-EXCH"/> <displayreference target="I-D.irtf-cfrg-bbs-signatures" to="BBS-SIG-SCHEME"/> <displayreference target="I-D.irtf-cfrg-hybrid-kems" to="PQ-KEM"/> <displayreference target="I-D.ounsworth-cfrg-kem-combiners" to="KEM-COMBINER"/> <references anchor="sec-combined-references"> <name>References</name> <references anchor="sec-normative-references"> <name>Normative References</name> <reference anchor="ML-KEM" target="https://nvlpubs.nist.gov/nistpubs/FIPS/NIST.FIPS.203.pdf"> <front><title>FIPS-203: Module-Lattice-based<title>Module-Lattice-Based Key-Encapsulation Mechanism Standard</title> <author><organization/><organization>NIST</organization> </author><date/><date year="2024" month="August"/> </front> <seriesInfo name="NIST FIPS" value="203"/> <seriesInfo name="DOI" value="10.6028/nist.fips.203"/> </reference> <reference anchor="ML-DSA" target="https://nvlpubs.nist.gov/nistpubs/FIPS/NIST.FIPS.204.pdf"> <front><title>FIPS-204: Module-Lattice-Based<title>Module-Lattice-Based Digital Signature Standard</title> <author><organization/><organization>NIST</organization> </author><date/><date year="2024" month="August"/> </front> <seriesInfo name="NIST FIPS" value="204"/> <seriesInfo name="DOI" value="10.6028/NIST.FIPS.204"/> </reference> <reference anchor="SLH-DSA" target="https://nvlpubs.nist.gov/nistpubs/FIPS/NIST.FIPS.205.pdf"> <front><title>FIPS-205: Stateless<title>Stateless Hash-Based Digital Signature Standard</title> <author><organization/><organization>NIST</organization> </author><date/><date year="2024" month="August"/> </front> <seriesInfo name="NIST FIPS" value="205"/> <seriesInfo name="DOI" value="10.6028/NIST.FIPS.205"/> </reference> <reference anchor="Shors" target="https://arxiv.org/pdf/quant-ph/9508027"> <front><title>Polynomial-time algorithms<title>Polynomial-Time Algorithms forprime factorizationPrime Factorization anddiscrete logarithmsDiscrete Logarithms on aquantum computer</title> <author>Quantum Computer</title> <author initials="P." surname="Shor" fullname="Peter W. Shor"> <organization/> </author><date>n.d.</date><date year="1996" month="January" day="25"/> </front> <refcontent>arXiv:quant-ph/9508027v2</refcontent> </reference> <reference anchor="Grovers" target="https://dl.acm.org/doi/10.1145/237814.237866"> <front> <title>A fast quantum mechanical algorithm for database search</title><author><author fullname="Lok K. Grover"> <organization/> </author><date>n.d.</date><date year="1996" month="July" day="01"/> </front> <seriesInfo name="DOI" value="10.1145/237814.237866"/> <refcontent>STOC '96: Proceedings of the twenty-eighth annual ACM symposium on Theory of Computing, pp. 212-219</refcontent> </reference> <reference anchor="RSA" target="https://dl.acm.org/doi/pdf/10.1145/359340.359342"> <front> <title>A Method for Obtaining Digital Signatures and Public-KeyCryptosystems+</title> <author>Cryptosystems</title> <author fullname="Ronald L. Rivest"> <organization/> </author><date/> </front> </reference> <reference anchor="RFC6090"> <front> <title>Fundamental Elliptic Curve Cryptography Algorithms</title> <author fullname="D. McGrew" initials="D." surname="McGrew"/> <author fullname="K. Igoe" initials="K." surname="Igoe"/><authorfullname="M. Salter" initials="M." surname="Salter"/> <date month="February" year="2011"/> <abstract> <t>This note describes the fundamental algorithms of Elliptic Curve Cryptography (ECC) as they were defined in some seminal references from 1994 and earlier. These descriptions may be useful for implementing the fundamental algorithms without using any of the specialized methods that were developed in following years. Only elliptic curves defined over fields of characteristic greater than three are in scope; these curves are those used in Suite B. This document is not an Internet Standards Track specification; it is published for informational purposes.</t> </abstract> </front> <seriesInfo name="RFC" value="6090"/> <seriesInfo name="DOI" value="10.17487/RFC6090"/> </reference> <reference anchor="RFC8391"> <front> <title>XMSS: eXtended Merkle Signature Scheme</title> <author fullname="A. Huelsing" initials="A." surname="Huelsing"/> <author fullname="D. Butin" initials="D." surname="Butin"/> <author fullname="S. Gazdag" initials="S." surname="Gazdag"/> <author fullname="J. Rijneveld" initials="J." surname="Rijneveld"/> <author fullname="A. Mohaisen"initials="A."surname="Mohaisen"/> <date month="May" year="2018"/> <abstract> <t>This note describes the eXtended Merkle Signature Scheme (XMSS), a hash-based digital signature system that is based on existing descriptions in scientific literature. This note specifies Winternitz One-Time Signature Plus (WOTS+), a one-time signature scheme; XMSS, a single-tree scheme; and XMSS^MT, a multi-tree variant of XMSS. Both XMSS and XMSS^MT use WOTS+ as a main building block. XMSS provides cryptographic digital signatures without relying on the conjectured hardness of mathematical problems. Instead, it is proven that it only relies on the properties of cryptographic hash functions. XMSS provides strong security guarantees and is even secure when the collision resistance of the underlying hash function is broken. It is suitable for compact implementations, is relatively simple to implement, and naturally resists side-channel attacks. Unlike most other signature systems, hash-based signatures can so far withstand known attacks using quantum computers.</t> </abstract> </front> <seriesInfo name="RFC" value="8391"/> <seriesInfo name="DOI" value="10.17487/RFC8391"/> </reference> <reference anchor="RFC8554"> <front> <title>Leighton-Micali Hash-Based Signatures</title> <author fullname="D. McGrew" initials="D." surname="McGrew"/> <author fullname="M. Curcio" initials="M." surname="Curcio"/> <author fullname="S. Fluhrer" initials="S." surname="Fluhrer"/> <date month="April" year="2019"/> <abstract> <t>This note describes a digital-signature system based on cryptographic hash functions, following the seminal work in this area of Lamport, Diffie, Winternitz, and Merkle, as adapted by Leighton and Micali in 1995. It specifies a one-time signature scheme and a general signature scheme. These systems provide asymmetric authentication without using large integer mathematics and can achieve a high security level. They are suitable for compact implementations, are relatively simple to implement, and are naturally resistant to side-channel attacks. Unlike many other signature systems, hash-based signatures would still be secure even if it proves feasible for an attacker to build a quantum computer.</t> <t>This document is a product of the Crypto Forum Research Group (CFRG) in the IRTF. This has been reviewed by many researchers, both in the research group and outside of it. The Acknowledgements section lists many of them.</t> </abstract> </front> <seriesInfo name="RFC" value="8554"/> <seriesInfo name="DOI" value="10.17487/RFC8554"/> </reference> <reference anchor="RFC8446"> <front> <title>The Transport Layer Security (TLS) Protocol Version 1.3</title>surname="Shamir"> <organization/> </author> <authorfullname="E. Rescorla" initials="E." surname="Rescorla"/>initials="L." surname="Adleman"> <organization/> </author> <datemonth="August" year="2018"/> <abstract> <t>This document specifies version 1.3 of the Transport Layer Security (TLS) protocol. TLS allows client/server applications to communicate over the Internet in a way that is designed to prevent eavesdropping, tampering, and message forgery.</t> <t>This document updates RFCs 5705 and 6066, and obsoletes RFCs 5077, 5246, and 6961. This document also specifies new requirements for TLS 1.2 implementations.</t> </abstract>year="1978" month="February"/> </front> <seriesInfoname="RFC" value="8446"/> <seriesInfoname="DOI"value="10.17487/RFC8446"/> </reference> <reference anchor="RFC4034"> <front> <title>Resource Records for the DNS Security Extensions</title> <author fullname="R. Arends" initials="R." surname="Arends"/> <author fullname="R. Austein" initials="R." surname="Austein"/> <author fullname="M. Larson" initials="M." surname="Larson"/> <author fullname="D. Massey" initials="D." surname="Massey"/> <author fullname="S. Rose" initials="S." surname="Rose"/> <date month="March" year="2005"/> <abstract> <t>This document is part of a family of documents that describe the DNS Security Extensions (DNSSEC). The DNS Security Extensions are a collectionvalue="10.1145/359340.359342"/> <refcontent>Communications ofresource records and protocol modifications that provide source authentication fortheDNS. This document defines the public key (DNSKEY), delegation signer (DS), resource record digital signature (RRSIG), and authenticated denial of existence (NSEC) resource records. The purpose and format of each resource record is described in detail, and an example of each resource record is given.</t> <t>This document obsoletes RFC 2535 and incorporates changes from all updates to RFC 2535. [STANDARDS-TRACK]</t> </abstract> </front> <seriesInfo name="RFC" value="4034"/> <seriesInfo name="DOI" value="10.17487/RFC4034"/>ACM, vol. 21, no. 2, pp. 120-126</refcontent> </reference> <xi:include href="https://bib.ietf.org/public/rfc/bibxml/reference.RFC.6090.xml"/> <xi:include href="https://bib.ietf.org/public/rfc/bibxml/reference.RFC.8391.xml"/> <xi:include href="https://bib.ietf.org/public/rfc/bibxml/reference.RFC.8554.xml"/> <xi:include href="https://bib.ietf.org/public/rfc/bibxml/reference.RFC.8446.xml"/> <xi:include href="https://bib.ietf.org/public/rfc/bibxml/reference.RFC.4034.xml"/> <reference anchor="NTRU" target="https://ntru.org/index.shtml"> <front> <title>NTRU</title> <author> <organization/> </author><date>n.d.</date><date/> </front> </reference> <reference anchor="FrodoKEM" target="https://frodokem.org/"> <front> <title>FrodoKEM</title> <author> <organization/> </author><date>n.d.</date><date/> </front> </reference> <reference anchor="ClassicMcEliece" target="https://classic.mceliece.org/"> <front> <title>Classic McEliece</title> <author> <organization/> </author><date>n.d.</date><date/> </front> </reference> <reference anchor="FN-DSA" target="https://falcon-sign.info/"> <front><title>Fast<title>FALCON: Fast Fourier lattice-based compact signatures over NTRU</title> <author> <organization/> </author> <date/> </front> </reference> <xi:include href="https://bib.ietf.org/public/rfc/bibxml/reference.RFC.8235.xml"/> <xi:include href="https://bib.ietf.org/public/rfc/bibxml/reference.RFC.9180.xml"/> <xi:include href="https://bib.ietf.org/public/rfc/bibxml/reference.RFC.9881.xml"/> <xi:include href="https://bib.ietf.org/public/rfc/bibxml/reference.RFC.9242.xml"/> <xi:include href="https://bib.ietf.org/public/rfc/bibxml/reference.RFC.9370.xml"/> </references> <references anchor="sec-informative-references"> <name>Informative References</name> <referenceanchor="RFC8235"> <front> <title>Schnorr Non-interactive Zero-Knowledge Proof</title> <author fullname="F. Hao" initials="F." role="editor" surname="Hao"/> <date month="September" year="2017"/> <abstract> <t>This document describes the Schnorr non-interactive zero-knowledge (NIZK) proof, a non-interactive variant of the three-pass Schnorr identification scheme. The Schnorr NIZK proof allows one to prove the knowledge of a discrete logarithm without leaking any information about its value. It can serve as a useful building block for many cryptographic protocols to ensure that participants follow the protocol specification honestly. This document specifies the Schnorr NIZK proof in both the finite field and the elliptic curve settings.</t> </abstract> </front> <seriesInfo name="RFC" value="8235"/> <seriesInfo name="DOI" value="10.17487/RFC8235"/> </reference> <reference anchor="RFC9180"> <front> <title>Hybrid Public Key Encryption</title> <author fullname="R. Barnes" initials="R." surname="Barnes"/> <author fullname="K. Bhargavan" initials="K." surname="Bhargavan"/> <author fullname="B. Lipp" initials="B." surname="Lipp"/> <author fullname="C. Wood" initials="C." surname="Wood"/> <date month="February" year="2022"/> <abstract> <t>This document describes a scheme for hybrid public key encryption (HPKE). This scheme provides a variant of public key encryption of arbitrary-sized plaintexts for a recipient public key. It also includes three authenticated variants, including one that authenticates possession of a pre-shared key and two optional ones that authenticate possession of a key encapsulation mechanism (KEM) private key. HPKE works for any combination of an asymmetric KEM, key derivation function (KDF), and authenticated encryption with additional data (AEAD) encryption function. Some authenticated variants may not be supported by all KEMs. We provide instantiations of the scheme using widely used and efficient primitives, such as Elliptic Curve Diffie-Hellman (ECDH) key agreement, HMAC-based key derivation function (HKDF), and SHA2.</t> <t>This document is a product of the Crypto Forum Research Group (CFRG) in the IRTF.</t> </abstract> </front> <seriesInfo name="RFC" value="9180"/> <seriesInfo name="DOI" value="10.17487/RFC9180"/> </reference> <reference anchor="I-D.ietf-lamps-dilithium-certificates">anchor="Serious-Crypt"> <front><title>Internet X.509 Public Key Infrastructure - Algorithm Identifiers for the Module-Lattice-Based Digital Signature Algorithm (ML-DSA)</title> <author fullname="Jake Massimo" initials="J." surname="Massimo"> <organization>AWS</organization> </author> <author fullname="Panos Kampanakis" initials="P." surname="Kampanakis"> <organization>AWS</organization> </author> <author fullname="Sean Turner" initials="S." surname="Turner"> <organization>sn3rd</organization> </author><title>Serious Cryptography, 2nd Edition</title> <authorfullname="Bas Westerbaan" initials="B." surname="Westerbaan"> <organization>Cloudflare</organization>fullname="Jean-Philippe Aumasson"> <organization/> </author> <dateday="26" month="June" year="2025"/> <abstract> <t> Digital signatures are used within X.509 certificates, Certificate Revocation Lists (CRLs), and to sign messages. This document specifies the conventions for using FIPS 204, the Module-Lattice- Based Digital Signature Algorithm (ML-DSA) in Internet X.509 certificates and certificate revocation lists. The conventions for the associated signatures, subject public keys, and private key are also described. </t> </abstract>year="2024" month="August"/> </front><seriesInfo name="Internet-Draft" value="draft-ietf-lamps-dilithium-certificates-12"/><refcontent>ISBN 9781718503847</refcontent> </reference> <referenceanchor="RFC9242">anchor="Grover-Search" target="https://link.aps.org/doi/10.1103/PhysRevA.60.2746"> <front><title>Intermediate Exchange in the Internet Key Exchange Protocol Version 2 (IKEv2)</title> <author fullname="V. Smyslov" initials="V." surname="Smyslov"/> <date month="May" year="2022"/> <abstract> <t>This document defines a new exchange, called "Intermediate Exchange", for the Internet Key Exchange Protocol Version 2 (IKEv2). This exchange can be used for transferring large amounts of data in the process of IKEv2 Security Association (SA) establishment. An example of the need to do this is using key exchange methods resistant to Quantum Computers (QCs) for IKE SA establishment. The Intermediate Exchange makes it possible to use the existing IKE fragmentation mechanism (which cannot be used in the initial IKEv2 exchange), helping to avoid IP fragmentation of large IKE messages if they need to be sent before IKEv2 SA<title>Grover's quantum searching algorithm isestablished.</t> </abstract> </front> <seriesInfo name="RFC" value="9242"/> <seriesInfo name="DOI" value="10.17487/RFC9242"/> </reference> <reference anchor="RFC9370"> <front> <title>Multiple Key Exchanges in the Internet Key Exchange Protocol Version 2 (IKEv2)</title> <author fullname="CJ. Tjhai" initials="CJ." surname="Tjhai"/> <author fullname="M. Tomlinson" initials="M." surname="Tomlinson"/> <author fullname="G. Bartlett" initials="G." surname="Bartlett"/> <author fullname="S. Fluhrer" initials="S." surname="Fluhrer"/> <author fullname="D. Van Geest" initials="D." surname="Van Geest"/>optimal</title> <authorfullname="O. Garcia-Morchon" initials="O." surname="Garcia-Morchon"/> <author fullname="V. Smyslov" initials="V." surname="Smyslov"/>fullname="Christof Zalka"> <organization/> </author> <datemonth="May" year="2023"/> <abstract> <t>This document describes how to extend the Internet Key Exchange Protocol Version 2 (IKEv2) to allow multiple key exchanges to take place while computing a shared secret during a Security Association (SA) setup.</t> <t>This document utilizes the IKE_INTERMEDIATE exchange, where multiple key exchanges are performed when an IKE SA is being established. It also introduces a new IKEv2 exchange, IKE_FOLLOWUP_KE, which is used for the same purpose when the IKE SA is being rekeyed or is creating additional Child SAs.</t> <t>This document updates RFC 7296 by renaming a Transform Type 4 from "Diffie-Hellman Group (D-H)" to "Key Exchange Method (KE)" and renaming a field in the Key Exchange Payload from "Diffie-Hellman Group Num" to "Key Exchange Method". It also renames an IANA registry for this Transform Type from "Transform Type 4 - Diffie- Hellman Group Transform IDs" to "Transform Type 4 - Key Exchange Method Transform IDs". These changes generalize key exchange algorithms that can be used in IKEv2.</t> </abstract>year="1999" month="October"/> </front> <seriesInfoname="RFC" value="9370"/> <seriesInfoname="DOI"value="10.17487/RFC9370"/> </reference> </references> <references anchor="sec-informative-references"> <name>Informative References</name> <reference anchor="Grover-search"> <front> <title>C. Zalka, “Grover’s quantum searching algorithm is optimal,” Physicalvalue="10.1103/PhysRevA.60.2746"/> <refcontent>Physical Review A, vol. 60, no. 4, pp.2746-2751, 1999.</title> <author> <organization/> </author> <date/> </front>2746-2751</refcontent> </reference> <reference anchor="Threat-Report" target="https://globalriskinstitute.org/publications/quantum-threat-timeline-report-2020/"> <front> <title>Quantum Threat Timeline Report 2020</title><author><author fullname="Michele Mosca"> <organization/> </author><date/><author fullname="Marco Piani"> <organization/> </author> <date year="2021" month="January" day="27"/> </front> <refcontent>Global Risk Institute</refcontent> </reference> <reference anchor="QC-DNS" target="https://www.icann.org/octo-031-en.pdf"> <front> <title>Quantum Computing and the DNS</title><author><author fullname="Paul Hoffman"> <organization/> </author><date/><date year="2024" month="April" day="22"/> </front> <refcontent>ICANN Office of the Chief Technology Officer, OCTO-031v2</refcontent> </reference> <reference anchor="NIST" target="https://csrc.nist.gov/projects/post-quantum-cryptography/post-quantum-cryptography-standardization"> <front> <title>Post-Quantum Cryptography Standardization</title> <author><organization/><organization>NIST</organization> </author> <date/> </front> </reference> <reference anchor="Cloudflare" target="https://blog.cloudflare.com/nist-post-quantum-surprise/"> <front><title>NIST’s<title>NIST's pleasant post-quantum surprise</title><author><author fullname="Bas Westerbaan"> <organization/> </author><date/><date year="2022" month="July" day="08"/> </front> <refcontent>Cloudflare Blog</refcontent> </reference> <reference anchor="CS01" target="https://eprint.iacr.org/2001/108"> <front> <title>Design and Analysis of Practical Public-Key Encryption Schemes Secure against Adaptive Chosen Ciphertext Attack</title><author><author fullname="Ronald Cramer"> <organization/> </author><date/><author fullname="Victor Shoup"> <organization/> </author> <date year="2001"/> </front> <refcontent>Cryptology ePrint Archive, Paper 2001/108</refcontent> </reference> <reference anchor="BHK09" target="https://eprint.iacr.org/2009/418"> <front> <title>Subtleties in the Definition of IND-CCA: When and How Should Challenge-Decryption be Disallowed?</title><author><author fullname="Mihir Bellare"> <organization/> </author><date/><author fullname="Dennis Hofheinz"> <organization/> </author> <author fullname="Eike Kiltz"> <organization/> </author> <date year="2009"/> </front> <refcontent>Cryptology ePrint Archive, Paper 2009/418</refcontent> </reference> <reference anchor="GMR88" target="https://people.csail.mit.edu/silvio/Selected%20Scientific%20Papers/Digital%20Signatures/A_Digital_Signature_Scheme_Secure_Against_Adaptive_Chosen-Message_Attack.pdf"> <front> <title>A digital signature scheme secure against adaptive chosen-messageattacks.</title> <author>attacks</title> <author fullname="Shafi Goldwasser"> <organization/> </author><date/><author fullname="Silvio Micali"> <organization/> </author> <author fullname="Ronald L. Rivest"> <organization/> </author> <date year="1988" month="April"/> </front> <seriesInfo name="DOI" value="10.1137/0217017"/> <refcontent>SIAM Journal on Computing, vol. 17, no. 2, pp. 281-308</refcontent> </reference> <reference anchor="PQCAPI" target="https://csrc.nist.gov/CSRC/media/Projects/Post-Quantum-Cryptography/documents/example-files/api-notes.pdf"> <front> <title>PQC - API notes</title> <author><organization/><organization>NIST</organization> </author> <date/> </front> </reference> <reference anchor="RSA8HRS" target="https://arxiv.org/abs/1905.09749"> <front> <title>How to factor 2048 bit RSA integers in 8 hours using 20 million noisy qubits</title><author><author fullname="Craig Gidney"> <organization/> </author><date/><author fullname="Martin Ekera"> <organization/> </author> <date year="2021" month="April" day="13"/> </front> <refcontent>arXiv:1905.09749v3</refcontent> </reference> <reference anchor="RSA10SC" target="https://www.quintessencelabs.com/blog/breaking-rsa-encryption-update-state-art"> <front> <title>Breaking RSA Encryption - an Update on the State-of-the-Art</title> <author><organization/><organization>QuintessenceLabs</organization> </author><date/><date year="2019" month="June" day="13"/> </front> </reference> <reference anchor="RSAShor" target="https://arxiv.org/pdf/quant-ph/0205095.pdf"> <front> <title>Circuit forShor’sShor's algorithm using 2n+3 qubits</title><author><author fullname="Stephane Beauregard"> <organization/> </author><date/><date year="2003" month="February" day="21"/> </front> <refcontent>arXiv:quant-ph/0205095v3</refcontent> </reference> <reference anchor="LIBOQS" target="https://github.com/open-quantum-safe/liboqs"> <front> <title>LibOQS - Open Quantum Safe</title> <author> <organization/> </author><date/><date year="2025" month="November"/> </front> <refcontent>commit 97f6b86</refcontent> </reference> <reference anchor="KyberSide" target="https://eprint.iacr.org/2022/1452"> <front> <title>A Side-Channel Attack on a Hardware Implementation of CRYSTALS-Kyber</title><author><author fullname="Yanning Ji"> <organization/> </author><date/><author fullname="Ruize Wang"> <organization/> </author> <author fullname="Kalle Ngo"> <organization/> </author> <author fullname="Elena Dubrova"> <organization/> </author> <author fullname="Linus Backlund"> <organization/> </author> <date year="2022"/> </front> <refcontent>Cryptology ePrint Archive, Paper 2022/1452</refcontent> </reference> <reference anchor="SaberSide" target="https://link.springer.com/article/10.1007/s13389-023-00315-3"> <front> <title>A side-channel attack on a masked and shuffled software implementation of Saber</title><author><author fullname="Kalle Ngo"> <organization/> </author><date/><author fullname="Elena Dubrova"> <organization/> </author> <author fullname="Thomas Johansson"> <organization/> </author> <date year="2023" month="April" day="25"/> </front> <seriesInfo name="DOI" value="10.1007/s13389-023-00315-3"/> <refcontent>Journal of Cryptographic Engineering, vol. 13, pp. 443-460</refcontent> </reference> <reference anchor="SideCh" target="https://eprint.iacr.org/2022/919"> <front> <title>Side-Channel Attacks on Lattice-Based KEMs Are Not Prevented by Higher-Order Masking</title><author><author fullname="Kalle Ngo"> <organization/> </author><date/><author fullname="Ruize Wang"> <organization/> </author> <author fullname="Elena Dubrova"> <organization/> </author> <author fullname="Nils Paulsrud"> <organization/> </author> <date year="2022"/> </front> <refcontent>Cryptology ePrint Archive, Paper 2022/919</refcontent> </reference> <reference anchor="LatticeSide" target="https://eprint.iacr.org/2019/948"> <front> <title>Generic Side-channel attacks on CCA-secure lattice-based PKE and KEM schemes</title><author><author fullname="Prasanna Ravi"> <organization/> </author><date/><author fullname="Sujoy Sinha Roy"> <organization/> </author> <author fullname="Anupam Chattopadhyay"> <organization/> </author> <author fullname="Shivam Bhasin"> <organization/> </author> <date year="2019"/> </front> <refcontent>Cryptology ePrint Archive, Paper 2019/948</refcontent> </reference> <reference anchor="Mitigate1" target="https://eprint.iacr.org/2022/873"> <front> <title>POLKA: Towards Leakage-Resistant Post-Quantum CCA-Secure Public Key Encryption</title><author><author fullname="Clément Hoffmann"> <organization/> </author><date/><author fullname="Benoît Libert"> <organization/> </author> <author fullname="Charles Momin"> <organization/> </author> <author fullname="Thomas Peters"> <organization/> </author> <author fullname="François-Xavier Standaert"> <organization/> </author> <date year="2022"/> </front> <refcontent>Cryptology ePrint Archive, Paper 2022/873</refcontent> </reference> <reference anchor="Mitigate2" target="https://ieeexplore.ieee.org/document/9855226"> <front> <title>Leakage-Resilient Certificate-Based Authenticated Key Exchange Protocol</title><author><author initials="T." surname="Tsai"> <organization/> </author><date/><author initials="S." surname="Huang"> <organization/> </author> <author initials="Y." surname="Tseng"> <organization/> </author> <author initials="Y." surname="Chuang"> <organization/> </author> <author initials="Y." surname="Hung"> <organization/> </author> <date year="2022"/> </front> <seriesInfo name="DOI" value="10.1109/OJCS.2022.3198073"/> <refcontent>IEEE Open Journal of the Computer Society, vol. 3, pp. 137-148</refcontent> </reference> <reference anchor="Mitigate3" target="https://eprint.iacr.org/2022/916"> <front> <title>Post-Quantum Authenticated Encryption against Chosen-Ciphertext Side-Channel Attacks</title><author><author fullname="Melissa Azouaoui"> <organization/> </author><date/><author fullname="Yulia Kuzovkova"> <organization/> </author> <author fullname="Tobias Schneider"> <organization/> </author> <author fullname="Christine van Vredendaal"> <organization/> </author> <date year="2022"/> </front> <refcontent>Cryptology ePrint Archive, Paper 2022/916</refcontent> </reference> <reference anchor="CNSA2-0" target="https://media.defense.gov/2025/May/30/2003728741/-1/-1/0/CSA_CNSA_2.0_ALGORITHMS.PDF"> <front> <title>Announcing the Commercial National Security Algorithm Suite 2.0</title> <author><organization/><organization>NSA</organization> </author><date/><date year="2022" month="September"/> </front> </reference> <reference anchor="LattFail1"target="https://link.springer.com/chapter/10.1007/978-3-030-17259-6_19#chapter-info">target="https://link.springer.com/chapter/10.1007/978-3-030-17259-6_19"> <front> <title>Decryption Failure Attacks on IND-CCA Secure Lattice-Based Schemes</title><author><author fullname="Jan-Pieter D'Anvers"> <organization/> </author><date/><author fullname="Qian Guo"> <organization/> </author> <author fullname="Thomas Johansson"> <organization/> </author> <author fullname="Alexander Nilsson"> <organization/> </author> <author fullname="Frederik Vercauteren"> <organization/> </author> <author fullname="Ingrid Verbauwhede"> <organization/> </author> <date year="2019" month="April" day="06"/> </front> <seriesInfo name="DOI" value="10.1007/978-3-030-17259-6_19"/> <refcontent>Public-Key Cryptography - PKC 2019, Lecture Notes in Computer Science, vol. 11443, pp. 565-598</refcontent> </reference> <reference anchor="LattFail2" target="https://link.springer.com/chapter/10.1007/978-3-030-45727-3_1"> <front> <title>(One) Failure Is Not an Option: Bootstrapping the Search for Failures in Lattice-Based EncryptionSchemes.</title> <author>Schemes</title> <author fullname="Jan-Pieter D'Anvers"> <organization/> </author><date/><author fullname="Mélissa Rossi"> <organization/> </author> <author fullname="Fernando Virdia"> <organization/> </author> <date year="2020" month="May" day="01"/> </front> <seriesInfo name="DOI" value="10.1007/978-3-030-45727-3_1"/> <refcontent>Advances in Cryptology - EUROCRYPT 2020, Lecture Notes in Computer Science, vol. 12107, pp. 3-33</refcontent> </reference> <reference anchor="BSI-PQC" target="https://www.bsi.bund.de/SharedDocs/Downloads/EN/BSI/Publications/Brochure/quantum-safe-cryptography.html?nn=916626"> <front> <title>Quantum-safe cryptography–- fundamentals, current developments and recommendations</title> <author><organization/><organization>BSI</organization> </author> <date year="2022"month="May"/>month="May" day="18"/> </front> </reference> <reference anchor="PQRSA" target="https://cr.yp.to/papers/pqrsa-20170419.pdf"> <front> <title>Post-quantum RSA</title><author><author fullname="Daniel J. Bernstein"> <organization/> </author> <author fullname="Nadia Heninger"> <organization/> </author> <author fullname="Paul Lou"> <organization/> </author> <author fullname="Luke Valenta"> <organization/> </author> <date year="2017"month="April"/>month="April" day="19"/> </front> </reference> <reference anchor="SP-800-56C" target="https://nvlpubs.nist.gov/nistpubs/SpecialPublications/NIST.SP.800-56Cr2.pdf"> <front> <title>Recommendation for Key-Derivation Methods in Key-Establishment Schemes</title><author><author fullname="Elaine Barker"> <organization/> </author><date/><author fullname="Lily Chen"> <organization/> </author> <author fullname="Richard Davis"> <organization/> </author> <date year="2020" month="August"/> </front> <seriesInfo name="NIST SP" value="800-56Cr2"/> <seriesInfo name="DOI" value="10.6028/NIST.SP.800-56Cr2"/> </reference> <reference anchor="Lyu09" target="https://www.iacr.org/archive/asiacrypt2009/59120596/59120596.pdf"> <front><title>V. Lyubashevsky, “Fiat-Shamir<title>Fiat-Shamir With Aborts: Applications to Lattice and Factoring-BasedSignatures“, ASIACRYPT 2009</title> <author>Signatures</title> <author fullname="Vadim Lyubashevsky"> <organization/> </author> <date/> </front> <refcontent>ASIACRYPT 2009</refcontent> </reference> <reference anchor="SP-1800-38C" target="https://www.nccoe.nist.gov/sites/default/files/2023-12/pqc-migration-nist-sp-1800-38c-preliminary-draft.pdf"> <front> <title>Migration to Post-Quantum Cryptography Quantum Readiness: Testing Draft Standards, Volume C: Quantum-Resistant Cryptography Technology Interoperability and Performance Report</title><author><author fullname="William Newhouse"> <organization/> </author><date/><author fullname="Murugiah Souppaya"> <organization/> </author> <author fullname="William Barke"> <organization/> </author> <author fullname="Chris Brown"> <organization/> </author> <author fullname="Panos Kampanakis"> <organization/> </author> <author fullname="Jim Goodman"> <organization/> </author> <author fullname="Julien Prat"> <organization/> </author> <author fullname="Robin Larrieu"> <organization/> </author> <author fullname="John Gray"> <organization/> </author> <author fullname="Mike Ounsworth"> <organization/> </author> <author fullname="Cleandro Viana"> <organization/> </author> <author fullname="Hubert Le Van Gong"> <organization/> </author> <author fullname="Kris Kwiatkowsk"> <organization/> </author> <author fullname="Anthony Hu"> <organization/> </author> <author fullname="Robert Burns"> <organization/> </author> <author fullname="Christian Paquin"> <organization/> </author> <author fullname="Jane Gilbert"> <organization/> </author> <author fullname="Gina Scinta"> <organization/> </author> <author fullname="Eunkyung Kim"> <organization/> </author> <author fullname="Volker Krumme"> <organization/> </author> <date year="2023" month="December"/> </front> <seriesInfo name="NIST SP" value="1800-38C"/> <refcontent>Preliminary Draft</refcontent> </reference> <reference anchor="KEEPINGUP" target="https://eprint.iacr.org/2023/1933"> <front> <title>Keeping Up with the KEMs: Stronger Security Notions for KEMs and automated analysis of KEM-based protocols</title><author><author fullname="Cas Cremers"> <organization/> </author><date>n.d.</date><author fullname="Alexander Dax"> <organization/> </author> <author fullname="Niklas Medinger"> <organization/> </author> <date year="2023"/> </front> <refcontent>Cryptology ePrint Archive, Paper 2023/1933</refcontent> </reference> <reference anchor="NISTFINAL" target="https://www.nist.gov/news-events/news/2024/08/nist-releases-first-3-finalized-post-quantum-encryption-standards"> <front> <title>NIST Releases First 3 Finalized Post-Quantum Encryption Standards</title> <author><organization/><organization>NIST</organization> </author><date>n.d.</date><date year="2024" month="August" day="13"/> </front> </reference> <reference anchor="ANSSI" target="https://cyber.gouv.fr/sites/default/files/document/follow_up_position_paper_on_post_quantum_cryptography.pdf"> <front> <title>ANSSI views on the Post-Quantum Cryptographytransition</title>transition (2023 follow up)</title> <author><organization/><organization>ANSSI</organization> </author><date>n.d.</date><date year="2023" month="December" day="21"/> </front> </reference> <reference anchor="HQC" target="http://pqc-hqc.org/"> <front> <title>HQC</title> <author> <organization/> </author><date>n.d.</date><date/> </front> </reference> <reference anchor="BIKE"target="http://pqc-hqc.org/">target="https://bikesuite.org/"> <front> <title>BIKE</title> <author> <organization/> </author><date>n.d.</date><date/> </front> </reference> <reference anchor="PQUIP-WG" target="https://datatracker.ietf.org/group/pquip/documents/"> <front> <title>Post-Quantum Use In Protocols(pquip) Working Group</title>(pquip)</title> <author><organization/><organization>IETF</organization> </author><date>n.d.</date><date/> </front> </reference> <reference anchor="OQS" target="https://openquantumsafe.org/"> <front> <title>Open Quantum Safe Project</title> <author> <organization/> </author><date>n.d.</date><date/> </front> </reference> <reference anchor="CRQCThreat" target="https://sam-jaques.appspot.com/quantum_landscape_2024"> <front><title>CRQCThreat</title> <author><title>Landscape of Quantum Computing</title> <author fullname="Sam Jaques"> <organization/> </author><date>n.d.</date><date/> </front> </reference> <reference anchor="QuantSide" target="https://arxiv.org/pdf/2304.03315"> <front><title>QuantSide</title> <author> <organization/> </author> <date>n.d.</date> </front> </reference> <reference anchor="AddSig" target="https://csrc.nist.gov/Projects/pqc-dig-sig/standardization"> <front> <title>AddSig</title> <author> <organization/> </author> <date>n.d.</date> </front> </reference> <reference anchor="BPQS" target="https://eprint.iacr.org/2018/658.pdf"> <front> <title>BPQS</title> <author> <organization/> </author> <date>n.d.</date> </front> </reference> <reference anchor="PCI" target="https://docs-prv.pcisecuritystandards.org/PCI%20DSS/Standard/PCI-DSS-v4_0_1.pdf"> <front> <title>Payment Card Industry Data Security Standard</title> <author> <organization/> </author> <date>n.d.</date> </front> </reference> <reference anchor="I-D.irtf-cfrg-bbs-signatures"> <front> <title>The BBS Signature Scheme</title> <author fullname="Tobias Looker" initials="T." surname="Looker"> <organization>MATTR</organization> </author> <author fullname="Vasilis Kalos" initials="V." surname="Kalos"> <organization>MATTR</organization> </author> <author fullname="Andrew Whitehead" initials="A." surname="Whitehead"> <organization>Portage</organization> </author> <author fullname="Mike Lodder" initials="M." surname="Lodder"> <organization>CryptID</organization> </author> <date day="7" month="July" year="2025"/> <abstract> <t> This document describes the BBS Signature scheme, a secure, multi- message digital signature protocol, supporting proving knowledge of a signature while selectively disclosing any subset of the signed messages. Concretely, the scheme allows for signing multiple messages whilst producing a single, constant size, digital signature. Additionally, the possessor of a BBS signatures is able to create zero-knowledge, proofs of knowledge of a signature, while selectively disclosing subsets of the signed messages. Being zero-knowledge, the BBS proofs do not reveal any information about the undisclosed messages or the signature itself, while at the same time, guaranteeing the authenticity and integrity of the disclosed messages. </t> </abstract> </front> <seriesInfo name="Internet-Draft" value="draft-irtf-cfrg-bbs-signatures-09"/> </reference> <reference anchor="I-D.ietf-sshm-ntruprime-ssh"> <front> <title>Secure Shell (SSH) Key Exchange Method Using Hybrid Streamlined NTRU Prime sntrup761 and X25519 with SHA-512: sntrup761x25519-sha512</title> <author fullname="Markus Friedl" initials="M." surname="Friedl"> <organization>OpenSSH</organization> </author> <author fullname="Jan Mojzis" initials="J." surname="Mojzis"> <organization>TinySSH</organization> </author> <author fullname="Simon Josefsson" initials="S." surname="Josefsson"> </author> <date day="15" month="August" year="2025"/> <abstract> <t> This document describes a widely deployed hybrid key exchange method in the Secure Shell (SSH) protocol that is based on Streamlined NTRU Prime sntrup761 and X25519 with SHA-512. </t> </abstract> </front> <seriesInfo name="Internet-Draft" value="draft-ietf-sshm-ntruprime-ssh-05"/> </reference> <reference anchor="RFC9528"> <front> <title>Ephemeral Diffie-Hellman Over COSE (EDHOC)</title> <author fullname="G. Selander" initials="G." surname="Selander"/> <author fullname="J. Preuß Mattsson" initials="J." surname="Preuß Mattsson"/> <author fullname="F. Palombini" initials="F." surname="Palombini"/> <date month="March" year="2024"/> <abstract> <t>This document specifies Ephemeral Diffie-Hellman Over COSE (EDHOC), a very compact and lightweight authenticated Diffie-Hellman key exchange with ephemeral keys. EDHOC provides mutual authentication, forward secrecy, and identity protection. EDHOC is intended for usage in constrained scenarios, and a main use case is to establish an Object Security for Constrained RESTful Environments (OSCORE) security context. By reusing CBOR Object Signing and Encryption (COSE) for cryptography, Concise Binary Object Representation (CBOR) for encoding, and Constrained Application Protocol (CoAP) for transport, the additional code size can be kept very low.</t> </abstract> </front> <seriesInfo name="RFC" value="9528"/> <seriesInfo name="DOI" value="10.17487/RFC9528"/> </reference> <reference anchor="I-D.draft-ounsworth-cfrg-kem-combiners"> <front> <title>Combiner function for hybrid key encapsulation mechanisms (Hybrid KEMs)</title> <author fullname="Mike Ounsworth" initials="M." surname="Ounsworth"> <organization>Entrust Limited</organization> </author> <author fullname="Aron Wussler" initials="A." surname="Wussler"> <organization>Proton AG</organization> </author> <author fullname="Stavros Kousidis" initials="S." surname="Kousidis"> <organization>BSI</organization> </author> <date day="31" month="January" year="2024"/> <abstract> <t> The migration to post-quantum cryptography often calls for performing multiple key encapsulations in parallel and then combining their outputs to derive a single shared secret. This document defines a comprehensible and easy to implement Keccak- based KEM combiner to join an arbitrary number of key shares, that is compatible with NIST SP 800-56Cr2 [SP800-56C] when viewed as a key derivation function. The combiners defined here are practical split- key PRFs and are CCA-secure as long as at least one<title>Exploration ofthe ingredient KEMs is. </t> </abstract> </front> <seriesInfo name="Internet-Draft" value="draft-ounsworth-cfrg-kem-combiners-05"/> </reference> <reference anchor="I-D.irtf-cfrg-hybrid-kems"> <front> <title>Hybrid PQ/T Key Encapsulation Mechanisms</title>Quantum Computer Power Side-Channels</title> <authorfullname="Deirdre Connolly" initials="D." surname="Connolly"> <organization>SandboxAQ</organization>fullname="Chuanqi Xu"> <organization/> </author> <authorfullname="Richard Barnes" initials="R." surname="Barnes"> <organization>Cisco</organization>fullname="Ferhat Erata"> <organization/> </author> <authorfullname="Paul Grubbs" initials="P." surname="Grubbs"> <organization>University of Michigan</organization>fullname="Jakub Szefer"> <organization/> </author> <dateday="20" month="July" year="2025"/> <abstract> <t> This document defines generic constructions for hybrid Key Encapsulation Mechanisms (KEMs) based on combining a traditional cryptographic component and a post-quantum (PQ) KEM. Hybrid KEMs built using these constructions provide strong security properties as long as either of the underlying algorithms are secure. </t> </abstract>year="2023" month="May" day="09"/> </front><seriesInfo name="Internet-Draft" value="draft-irtf-cfrg-hybrid-kems-05"/><refcontent>arXiv:2304.03315v2</refcontent> </reference> <referenceanchor="I-D.ietf-hpke-pq">anchor="AddSig" target="https://csrc.nist.gov/Projects/pqc-dig-sig/standardization"> <front> <title>Post-Quantumand Post-Quantum/Traditional Hybrid Algorithms for HPKE</title> <author fullname="Richard Barnes" initials="R." surname="Barnes"> <organization>Cisco</organization> </author> <date day="30" month="June" year="2025"/> <abstract> <t> Updating key exchange and public-key encryption protocols to resist attack by quantum computers is a high priority given the possibility of "harvest now, decrypt later" attacks. Hybrid Public Key Encryption (HPKE) is a widely-used public key encryption scheme based on combining a Key Encapsulation Mechanism (KEM), a Key Derivation Function (KDF), and an Authenticated Encryption with Associated Data (AEAD) scheme. In this document, we define KEM algorithms for HPKE based on both post-quantum KEMs and hybrid constructions of post- quantum KEMs with traditional KEMs, as well as a KDF based on SHA-3 that is suitable for use with these KEMs. When used with these algorithms, HPKE is resilient with respect to attacks by a quantum computer. </t> </abstract> </front> <seriesInfo name="Internet-Draft" value="draft-ietf-hpke-pq-01"/> </reference> <reference anchor="I-D.draft-connolly-cfrg-xwing-kem"> <front> <title>X-Wing: general-purpose hybrid post-quantum KEM</title> <author fullname="Deirdre Connolly" initials="D." surname="Connolly"> <organization>SandboxAQ</organization> </author> <author fullname="Peter Schwabe" initials="P." surname="Schwabe"> <organization>MPI-SP & Radboud University</organization> </author> <author fullname="Bas Westerbaan" initials="B." surname="Westerbaan"> <organization>Cloudflare</organization> </author> <date day="7" month="July" year="2025"/> <abstract> <t> This memo defines X-Wing, a general-purpose post-quantum/traditional hybrid key encapsulation mechanism (PQ/T KEM) built on X25519 and ML- KEM-768. </t> </abstract> </front> <seriesInfo name="Internet-Draft" value="draft-connolly-cfrg-xwing-kem-08"/> </reference> <reference anchor="RFC5652"> <front> <title>Cryptographic Message Syntax (CMS)</title> <author fullname="R. Housley" initials="R." surname="Housley"/> <date month="September" year="2009"/> <abstract> <t>This document describes the Cryptographic Message Syntax (CMS). This syntax is used to digitally sign, digest, authenticate, or encrypt arbitrary message content. [STANDARDS-TRACK]</t> </abstract> </front> <seriesInfo name="STD" value="70"/> <seriesInfo name="RFC" value="5652"/> <seriesInfo name="DOI" value="10.17487/RFC5652"/> </reference> <reference anchor="I-D.ietf-lamps-cms-sphincs-plus"> <front> <title>Use of the SLH-DSACryptography: Additional Digital SignatureAlgorithm in the Cryptographic Message Syntax (CMS)</title> <author fullname="Russ Housley" initials="R." surname="Housley"> <organization>Vigil Security, LLC</organization> </author> <author fullname="Scott Fluhrer" initials="S." surname="Fluhrer"> <organization>Cisco Systems</organization> </author> <author fullname="Panos Kampanakis" initials="P." surname="Kampanakis"> <organization>Amazon Web Services</organization> </author> <author fullname="Bas Westerbaan" initials="B." surname="Westerbaan"> <organization>Cloudflare</organization> </author> <date day="13" month="January" year="2025"/> <abstract> <t> SLH-DSA is a stateless hash-based signature scheme. This document specifies the conventions for using the SLH-DSA signature algorithm with the Cryptographic Message Syntax (CMS). In addition, the algorithm identifier and public key syntax are provided. </t> </abstract> </front> <seriesInfo name="Internet-Draft" value="draft-ietf-lamps-cms-sphincs-plus-19"/> </reference> <reference anchor="I-D.ietf-pquip-pqt-hybrid-terminology"> <front> <title>Terminology for Post-Quantum Traditional HybridSchemes</title><author fullname="Flo D" initials="F." surname="D"> <organization>UK National Cyber Security Centre</organization> </author> <author fullname="Michael P" initials="M." surname="P"> <organization>UK National Cyber Security Centre</organization> </author> <author fullname="Britta Hale" initials="B." surname="Hale"> <organization>Naval Postgraduate School</organization><author> <organization>NIST</organization> </author><date day="10" month="January" year="2025"/> <abstract> <t> One aspect of the transition to post-quantum algorithms in cryptographic protocols is the development of hybrid schemes that incorporate both post-quantum and traditional asymmetric algorithms. This document defines terminology for such schemes. It is intended to be used as a reference and, hopefully, to ensure consistency and clarity across different protocols, standards, and organisations. </t> </abstract><date/> </front><seriesInfo name="Internet-Draft" value="draft-ietf-pquip-pqt-hybrid-terminology-06"/></reference> <referenceanchor="I-D.ietf-tls-hybrid-design">anchor="BPQS" target="https://eprint.iacr.org/2018/658"> <front><title>Hybrid key exchange in TLS 1.3</title> <author fullname="Douglas Stebila" initials="D." surname="Stebila"> <organization>University of Waterloo</organization> </author><title>Blockchained Post-Quantum Signatures</title> <authorfullname="Scott Fluhrer" initials="S." surname="Fluhrer"> <organization>Cisco Systems</organization>fullname="Konstantinos Chalkias"> <organization/> </author> <authorfullname="Shay Gueron" initials="S." surname="Gueron"> <organization>University of Haifa and Meta</organization>fullname="James Brown"> <organization/> </author><date day="21" month="July" year="2025"/> <abstract> <t> Hybrid key exchange refers to using multiple key exchange algorithms simultaneously and combining the result with the goal of providing security even if a way is found to defeat the encryption for all but one of the component algorithms. It is motivated by transition to post-quantum cryptography. This document provides a construction for hybrid key exchange in the Transport Layer Security (TLS) protocol version 1.3. </t> </abstract> </front> <seriesInfo name="Internet-Draft" value="draft-ietf-tls-hybrid-design-14"/> </reference> <reference anchor="I-D.ietf-lamps-pq-composite-sigs"> <front> <title>Composite ML-DSA for use in X.509 Public Key Infrastructure</title><author fullname="MikeOunsworth" initials="M." surname="Ounsworth"> <organization>Entrust Limited</organization> </author> <author fullname="John Gray" initials="J." surname="Gray"> <organization>Entrust Limited</organization>Hearn"> <organization/> </author> <authorfullname="Massimiliano Pala" initials="M." surname="Pala"> <organization>OpenCA Labs</organization>fullname="Tommy Lillehagen"> <organization/> </author> <authorfullname="Jan Klaußner" initials="J." surname="Klaußner"> <organization>Bundesdruckerei GmbH</organization>fullname="Igor Nitto"> <organization/> </author> <authorfullname="Scott Fluhrer" initials="S." surname="Fluhrer"> <organization>Cisco Systems</organization>fullname="Thomas Schroeter"> <organization/> </author><date day="7" month="July" year="2025"/> <abstract> <t> This document defines combinations of ML-DSA [FIPS.204] in hybrid with traditional algorithms RSASSA-PKCS1-v1_5, RSASSA-PSS, ECDSA, Ed25519, and Ed448. These combinations are tailored to meet security best practices and regulatory guidelines. Composite ML-DSA is applicable in any application that uses X.509 or PKIX data structures that accept ML-DSA, but where the operator wants extra protection against breaks or catastrophic bugs in ML-DSA. </t> </abstract></front><seriesInfo name="Internet-Draft" value="draft-ietf-lamps-pq-composite-sigs-07"/><refcontent>Cryptology ePrint Archive, Paper 2018/658</refcontent> </reference> <referenceanchor="I-D.ietf-lamps-cert-binding-for-multi-auth">anchor="PCI" target="https://docs-prv.pcisecuritystandards.org/PCI%20DSS/Standard/PCI-DSS-v4_0_1.pdf"> <front><title>Related Certificates for Use in Multiple Authentications within a Protocol</title> <author fullname="Alison Becker" initials="A." surname="Becker"> <organization>National Security Agency</organization> </author> <author fullname="Rebecca Guthrie" initials="R." surname="Guthrie"> <organization>National<title>Payment Card Industry Data SecurityAgency</organization> </author> <author fullname="Michael J. Jenkins" initials="M. J." surname="Jenkins"> <organization>NationalStandard</title> <author> <organization>PCI SecurityAgency</organization> </author> <date day="10" month="December" year="2024"/> <abstract> <t> This document defines a new CSR attribute, relatedCertRequest, and a new X.509 certificate extension, RelatedCertificate. The use of the relatedCertRequest attribute in a CSR and the inclusion of the RelatedCertificate extension in the resulting certificate together provide additional assurance that two certificates each belong to the same end entity. This mechanism is particularly useful in the context of non-composite hybrid authentication, which enables users to employ the same certificates in hybrid authentication as in authentication done with only traditional or post-quantum algorithms. </t> </abstract> </front> <seriesInfo name="Internet-Draft" value="draft-ietf-lamps-cert-binding-for-multi-auth-06"/> </reference> <reference anchor="I-D.draft-bonnell-lamps-chameleon-certs"> <front> <title>A Mechanism for Encoding Differences in Paired Certificates</title> <author fullname="Corey Bonnell" initials="C." surname="Bonnell"> <organization>DigiCert</organization> </author> <author fullname="John Gray" initials="J." surname="Gray"> <organization>Entrust</organization> </author> <author fullname="D. Hook" initials="D." surname="Hook"> <organization>KeyFactor</organization> </author> <author fullname="Tomofumi Okubo" initials="T." surname="Okubo"> <organization>DigiCert</organization> </author> <author fullname="Mike Ounsworth" initials="M." surname="Ounsworth"> <organization>Entrust</organization>Standards Council</organization> </author><date day="16" month="April" year="2025"/> <abstract> <t> This document specifies a method to efficiently convey the differences between two certificates in an X.509 version 3 extension. This method allows a relying party to extract information sufficient to reconstruct the paired certificate and perform certification path validation using the reconstructed certificate. In particular, this method is especially useful as part of a key or signature algorithm migration, where subjects may be issued multiple certificates containing different public keys or signed with different CA private keys or signature algorithms. This method does not require any changes to the certification path validation algorithm as described in RFC 5280. Additionally, this method does not violate the constraints of serial number uniqueness for certificates issued by a single certification authority. </t> </abstract><date/> </front><seriesInfo name="Internet-Draft" value="draft-bonnell-lamps-chameleon-certs-06"/> </reference><refcontent>PCI DSS: v4.0.1</refcontent> </reference> <xi:include href="https://bib.ietf.org/public/rfc/bibxml3/reference.I-D.bonnell-lamps-chameleon-certs.xml"/> <xi:include href="https://bib.ietf.org/public/rfc/bibxml3/reference.I-D.connolly-cfrg-xwing-kem.xml"/> <referenceanchor="I-D.draft-ietf-pquip-hybrid-signature-spectrums">anchor="I-D.ietf-mls-combiner" target="https://datatracker.ietf.org/doc/html/draft-ietf-mls-combiner-02"> <front><title>Hybrid signature spectrums</title><title>Amortized PQ MLS Combiner</title> <authorfullname="Nina Bindel" initials="N." surname="Bindel"> <organization>SandboxAQ</organization>initials="X." surname="Tian" fullname="Xisen Tian"> <organization>Naval Postgraduate School</organization> </author> <authorfullname="Britta Hale"initials="B."surname="Hale">surname="Hale" fullname="Britta Hale"> <organization>Naval Postgraduate School</organization> </author> <authorfullname="Deirdre Connolly" initials="D." surname="Connolly"> <organization>SandboxAQ</organization>initials="M." surname="Mularczyk" fullname="Marta Mularczyk"> <organization>AWS</organization> </author> <authorfullname="Flo D" initials="F." surname="D"> <organization>UK National Cyber Security Centre</organization>initials="J." surname="Alwen" fullname="Joël Alwen"> <organization>AWS</organization> </author> <dateday="20" month="June"month="October" day="22" year="2025"/><abstract> <t> This document describes classification of design goals and security considerations for hybrid digital signature schemes, including proof composability, non-separability of the component signatures given a hybrid signature, backwards/forwards compatibility, hybrid generality, and simultaneous verification. </t> </abstract></front> <seriesInfo name="Internet-Draft"value="draft-ietf-pquip-hybrid-signature-spectrums-07"/>value="draft-ietf-mls-combiner-02"/> </reference> <xi:include href="https://bib.ietf.org/public/rfc/bibxml3/reference.I-D.ietf-hpke-pq.xml"/> <xi:include href="https://bib.ietf.org/public/rfc/bibxml3/reference.I-D.ietf-lamps-pq-composite-sigs.xml"/> <xi:include href="https://bib.ietf.org/public/rfc/bibxml3/reference.I-D.ietf-pquip-hybrid-signature-spectrums.xml"/> <referenceanchor="I-D.ietf-pquip-pqc-hsm-constrained">anchor="I-D.ietf-pquip-pqc-hsm-constrained" target="https://datatracker.ietf.org/doc/html/draft-ietf-pquip-pqc-hsm-constrained-05"> <front><title>Adapting<title> Adapting Constrained Devices for Post-QuantumCryptography</title>Cryptography </title> <authorfullname="Tirumaleswar Reddy.K"initials="T."surname="Reddy.K">surname="Reddy.K" fullname="Tirumaleswar Reddy.K"> <organization>Nokia</organization> </author> <authorfullname="Dan Wing"initials="D."surname="Wing"> <organization>Cloud Software Group Holdings, Inc.</organization>surname="Wing" fullname="Dan Wing"> <organization>Citrix</organization> </author> <authorfullname="Ben S"initials="B."surname="S">surname="Salter" fullname="Ben Salter"> <organization>UK National Cyber Security Centre</organization> </author> <authorfullname="Kris Kwiatkowski"initials="K."surname="Kwiatkowski">surname="Kwiatkowski" fullname="Kris Kwiatkowski"> <organization>PQShield</organization> </author> <dateday="4" month="July" year="2025"/> <abstract> <t> This document offers guidance on incorporating Post-Quantum Cryptography (PQC) into resource-constrained devices, including IoT devices and lightweight Hardware Security Modules (HSMs), which operate under tight limitations on compute power, memory, storage, and energy. It highlights how the Root of Trust acts as the foundation for secure operations, enabling features such as seed- based key generation to reduce the need for persistent storage, efficient approaches to managing ephemeral keys, and methods for offloading cryptographic tasks in low-resource environments. Additionally, it examines how PQC affects firmware update mechanisms in such constrained systems. </t> </abstract> </front> <seriesInfo name="Internet-Draft" value="draft-ietf-pquip-pqc-hsm-constrained-01"/> </reference> <reference anchor="I-D.hale-mls-combiner"> <front> <title>Flexible Hybrid PQ MLS Combiner</title> <author fullname="Joël" initials="" surname="Joël"> <organization>AWS</organization> </author> <author fullname="Britta Hale" initials="B." surname="Hale"> <organization>Naval Postgraduate School</organization> </author> <author fullname="Marta Mularczyk" initials="M." surname="Mularczyk"> <organization>AWS</organization> </author> <author fullname="Xisen Tian" initials="X." surname="Tian"> <organization>Naval Postgraduate School</organization> </author> <date day="26" month="September" year="2024"/> <abstract> <t> This document describes a protocol for combining a traditional MLS session with a post-quantum (PQ) MLS session to achieve flexible and efficient hybrid PQ security that amortizes the computational cost of PQ Key Encapsulation Mechanisms and Digital Signature Algorithms. Specifically, we describe how to use the exporter secret of a PQ MLS session, i.e. an MLS session using a PQ ciphersuite, to seed PQ guarantees into an MLS session using a traditional ciphersuite. By supporting on-demand traditional-only key updates (a.k.a. PARTIAL updates) or hybrid-PQ key updates (a.k.a. FULL updates), we can reduce the bandwidth and computational overhead associated with PQ operations while meeting the requirement of frequent key rotations. </t> </abstract>month="April" day="1" year="2026"/> </front> <seriesInfo name="Internet-Draft"value="draft-hale-mls-combiner-01"/>value="draft-ietf-pquip-pqc-hsm-constrained-05"/> </reference> <xi:include href="https://bib.ietf.org/public/rfc/bibxml3/reference.I-D.ietf-tls-hybrid-design.xml"/> <xi:include href="https://bib.ietf.org/public/rfc/bibxml3/reference.I-D.irtf-cfrg-bbs-signatures.xml"/> <xi:include href="https://bib.ietf.org/public/rfc/bibxml3/reference.I-D.irtf-cfrg-hybrid-kems.xml"/> <xi:include href="https://bib.ietf.org/public/rfc/bibxml3/reference.I-D.ounsworth-cfrg-kem-combiners.xml"/> <xi:include href="https://bib.ietf.org/public/rfc/bibxml/reference.RFC.9941.xml"/> <xi:include href="https://bib.ietf.org/public/rfc/bibxml/reference.RFC.9528.xml"/> <xi:include href="https://bib.ietf.org/public/rfc/bibxml/reference.RFC.5652.xml"/> <xi:include href="https://bib.ietf.org/public/rfc/bibxml/reference.RFC.9814.xml"/> <xi:include href="https://bib.ietf.org/public/rfc/bibxml/reference.RFC.9794.xml"/> <xi:include href="https://bib.ietf.org/public/rfc/bibxml/reference.RFC.9763.xml"/> </references> </references><?line 855?><section numbered="false" anchor="acknowledgements"> <name>Acknowledgements</name> <t>This document leverages text from an earlierdraftInternet-Draft byPaul Hoffman.<contact fullname="Paul Hoffman"/>. Thanks toDan Wing, Florence D, Thom Wiggers, Sophia Grundner-Culemann, Panos Kampanakis, Ben S, Sofia Celi, Melchior Aelmans, Falko Strenzke, Deirdre Connolly, Hani Ezzadeen, Britta Hale, Scott Rose, Hilarie Orman, Thomas Fossati, Roman Danyliw, Mike Bishop, Mališa Vučinić, Éric Vyncke, Deb Cooley, Dirk<contact fullname="Dan Wing"/>, <contact fullname="Florence D"/>, <contact fullname="Thom Wiggers"/>, <contact fullname="Sophia Grundner-Culemann"/>, <contact fullname="Panos Kampanakis"/>, <contact fullname="Ben S"/>, <contact fullname="Sofia Celi"/>, <contact fullname="Melchior Aelmans"/>, <contact fullname="Falko Strenzke"/>, <contact fullname="Deirdre Connolly"/>, <contact fullname="Hani Ezzadeen"/>, <contact fullname="Britta Hale"/>, <contact fullname="Scott Rose"/>, <contact fullname="Hilarie Orman"/>, <contact fullname="Thomas Fossati"/>, <contact fullname="Roman Danyliw"/>, <contact fullname="Mike Bishop"/>, <contact fullname="Mališa Vučinić"/>, <contact fullname="Éric Vyncke"/>, <contact fullname="Deb Cooley"/>, <contact fullname="Dirk VonHugoHugo"/>, andDaniel<contact fullname="Daniel VanGeestGeest"/> for the discussion, review and comments.</t> <t>In particular, the authors would like to acknowledge the contributions to this document byKris Kwiatkowski.</t> </section> </back><contact fullname="Kris Kwiatkowski"/>.</t> <!--##markdown-source: H4sIAAAAAAAAA+S96XIbWZYm+J9P4cWwtiI7AXDVQsVkd1EUFaJpCYagyKiZ 6WmlA3CQngTcEe4OMhBMjeXP+T31Y6zNep5m3iSfZM53lrs4HJSUmZ1V3a3M kEjAl3vPvffs5zv9fn+ryZtZ9izZvizrpv/DMi2a5Tw5q1aLpryq0sX1KpmW VXJeXOVFllX19lY6GlXZLe744az93ThtsquyWj1L8mJabm1NynGRzunxkyqd Nv08a6b9xc/LfEF/j/uZ3dif0X11s1UvR/O8rvOyaFYLuuvi/MPLrWI5H2XV s60JXfNsa1wWdVbUy/pZ0lTLbIsGcrSVVllKAxpm42WVN6vtrbuyurmqyuWC h/njxeX21k22ok8nz7aSfkIj39raus2KJT0xSexKHtk2fSBv3/6JnpIXV8l3 +B6fz9N8xteN/wlTGZTVFT5Oq/E1fXzdNIv62d4ersJH+W02sMv28MHeqCrv 6myP7t/bpgHUTVpMPqazsqC3rbJ6a5E/S/73phz3krqsmiqb1vTTaq4/NFU+ bnrJuJzPs6KhT4i683SxoCH+H1tb6bK5LitMj0aUJNPlbCakPyWSVGnyPC2y 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Updates of this nature typically result in more precise language, which is helpful for readers. For example, please consider whether "tradition" should be updated for clarity. While the NIST website <https://web.archive.org/web/20250214092458/https://www.nist.gov/nist-research-library/nist-technical-series-publications-author-instructions#table1> indicates that this term is potentially biased, it is also ambiguous. "Tradition" is a subjective term, as it is not the same for everyone. --> </section> </back> </rfc>