Internet Engineering Task Force (IETF) O. Steele
Request for Comments: 9942 Tradeverifyd
Category: Standards Track H. Birkholz
ISSN: 2070-1721 Fraunhofer SIT
A. Delignat-Lavaud
C. Fournet
Microsoft
April 2026
CBOR Object Signing and Encryption (COSE) Receipts
Abstract
CBOR Object Signing and Encryption (COSE) Receipts prove properties
of a Verifiable Data Structure (VDS) to a verifier. VDSs Verifiable Data
Structures and associated Proof Types enable security properties,
such as minimal disclosure, transparency, and non-equivocation.
Transparency helps maintain trust over time and has been applied to
certificates, end-
to-end end-to-end encrypted messaging systems, and supply
chain security. This specification enables concise transparency-oriented transparency-
oriented systems by building on Concise Binary Object Representation
(CBOR) and COSE. The extensibility of the approach is demonstrated
by providing CBOR encodings for Merkle inclusion and consistency
proofs.
Status of This Memo
This is an Internet Standards Track document.
This document is a product of the Internet Engineering Task Force
(IETF). It represents the consensus of the IETF community. It has
received public review and has been approved for publication by the
Internet Engineering Steering Group (IESG). Further information on
Internet Standards is available in Section 2 of RFC 7841.
Information about the current status of this document, any errata,
and how to provide feedback on it may be obtained at
https://www.rfc-editor.org/info/rfc9942.
Copyright Notice
Copyright (c) 2026 IETF Trust and the persons identified as the
document authors. All rights reserved.
This document is subject to BCP 78 and the IETF Trust's Legal
Provisions Relating to IETF Documents
(https://trustee.ietf.org/license-info) in effect on the date of
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Trust Legal Provisions and are provided without warranty as described
in the Revised BSD License.
Table of Contents
1. Introduction
1.1. Requirements Notation
2. New COSE Header Parameters
3. Terminology
4. VDSs Verifiable Data Structures in CBOR
4.1. Structures
4.2. Proofs
4.3. Usage
4.4. Profiles
4.4.1. Registration Requirements
5. RFC9162_SHA256
5.1. Verifiable Data Structure
5.2. Inclusion Proof
5.2.1. Receipt of Inclusion
5.3. Consistency Proof
5.3.1. Receipt of Consistency
6. Privacy Considerations
6.1. Log Length
6.2. Header Parameters
7. Security Considerations
7.1. Choice of Signature Algorithms
7.2. Validity Period
7.3. Status Updates
8. IANA Considerations
8.1. COSE Header Parameter
8.2. VDS Verifiable Data Structure Registries
8.2.1. Expert Review
8.2.2. Templates and Initial Contents
9. References
9.1. Normative References
9.2. Informative References
Acknowledgements
Contributors
Authors' Addresses
1. Introduction
COSE Receipts are signed proofs that include metadata about certain
states of a Verifiable Data Structure (VDS) that are true when the
COSE Receipt was issued. COSE Receipts can include proofs that a
document is in a database (proof of inclusion), that a database is
append-only (proof of consistency), that a smaller set of statements
are contained in a large set of statements (proof of disclosure, a
special case of proof of inclusion), or that certain data is not yet
present in a database (proof of non-inclusion). Different VDSs can
produce different Verifiable Data Structure Proofs (VDPs). (VDP). The
combination of representations of various VDSs and VDP can
significantly increase the burden for implementers and create
interoperability challenges for transparency services. This document
describes how to convey VDS and associated VDP types in unified COSE
envelopes.
1.1. Requirements Notation
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and
"OPTIONAL" in this document are to be interpreted as described in
BCP 14 [RFC2119] [RFC8174] when, and only when, they appear in all
capitals, as shown here.
2. New COSE Header Parameters
This document defines three new COSE header parameters, which are
introduced up front in this section and elaborated on later in this
document.
394: A COSE header parameter named "receipts" with a value type of
array where the array contains one or more COSE Receipts as
specified in this document.
395: A COSE header parameter named "vds" (for Verifiable Data
Structure), which conveys the algorithm identifier for a VDS.
Verifiable Data Structure. Correspondingly, see Section 8.2.2.1
for a registry defining the integers used to identify VDSs. Verifiable
Data Structures.
396: A COSE header parameter named "vdp" (for VDPs), Verifiable Data
Structure Proofs), which conveys a map containing VDPs Verifiable Data
Structure Proofs organized by Proof Type. Correspondingly, see
Section 8.2.2.2 for a registry defining the integers used to
identify VDP Verifiable Data Structure Proof Types.
3. Terminology
The terms "header" and "payload" are defined in [STD96].
Additionally, this document uses the following terminology:
CDDL: Concise Data Definition Language (CDDL) is defined in
[RFC8610].
EDN: CBOR Extended Diagnostic Notation (EDN) is defined in
[RFC8949], where it is referred to as "diagnostic notation", and
is revised in [CBOR-EDN].
Entry: An entry in
Verifiable Data Structure (VDS): A data structure that supports one
or more Verifiable Data Structure Proof Types. This property
describes an algorithm used to maintain a VDS Verifiable Data
Structure, for which proofs example, a binary Merkle Tree algorithm.
Verifiable Data Structure Proofs (VDP): A data structure used to
convey Proof Types for proving different properties, such as
authentication, inclusion, consistency, and freshness. Parameters
can be derived. include multiple proofs of a given type or multiple types of
proof (inclusion and consistency).
Proof Type: A property that can be obtained by verifying a given
proof over one or more entries in a VDS. Verifiable Data Structure.
For example, a VDS, such as a binary Merkle Tree, can support
inclusion proofs where each proof confirms that a given entry is
included in a Merkle Tree root.
Proof Value: An encoding of a Proof Type in CBOR [RFC8949].
Entry: An entry in a Verifiable Data Structure for which proofs can
be derived.
Receipt: A COSE Single Signer Data Object, as defined in RFC 9052
[STD96], [RFC9052],
containing the header parameters necessary to convey one or more
VDP for an associated VDS.
4. Verifiable Data Structure (VDS): A data structure that supports one
or more VDP Proof Types. This property describes an algorithm
used to maintain a VDS, for example, a binary Merkle Tree
algorithm.
Verifiable Data Structure Proofs (VDPs): A data structure used to
convey Proof Types for proving different properties, such as
authentication, inclusion, consistency, and freshness. Parameters
can include multiple proofs of a given type or multiple types of
proof (inclusion and consistency).
4. VDSs Structures in CBOR
This section describes representations of VDPs Verifiable Data Structure
Proofs in [RFC8949]. For example, construction of a Merkle Tree leaf
or an inclusion proof from a leaf to a Merkle Tree root might have
several different representations, depending on the VDS Verifiable Data
Structure used. Differences in representations are necessary to
support efficient verification, unique security or privacy
properties, and for compatibility with specific implementations.
This document defines two extension points for enabling VDSs Verifiable
Data Structures with COSE and provides concrete examples for the
structures and proofs defined in Section 2.1.3 of [RFC9162] and
Section 2.1.4 of [RFC9162]. The design of these structures is
influenced by the conventions established for COSE Keys.
4.1. Structures
Similar to COSE Key Types [IANA.cose_header-parameters], different
VDSs
Verifiable Data Structures support different algorithms.
This document establishes a registry of VDS Verifiable Data Structure
algorithms; see Section 8.2.2.1 for details.
4.2. Proofs
As is the case for
Similar to COSE Key Type Parameters [IANA.cose_header-parameters],
for example EC2 keys (1: 2) require and give meaning to specific
parameters, such as -1 (crv), -2 (x), -3 (y), and -4 (d). RFC9162_SHA256
(395: 1) supports both (-1) inclusion and (-2) consistency proofs.
This document establishes a registry of VDPs; Verifiable Data Structure
Proofs; see Section 8.2.2.2 for details.
Proof Types are specific to their associated "VDS"; "Verifiable Data
Structure"; for example, different Merkle Trees might support
different representations of inclusion proof or consistency proof.
Implementers should not expect interoperability across "VDSs". "Verifiable
Data Structures". Security analysis MUST be conducted prior to
migrating to new structures to ensure the new security and privacy
assumptions are acceptable for the use case.
4.3. Usage
This document registers a new COSE header parameter "receipts" (394)
to enable Receipts to be conveyed in the protected and unprotected
headers of Enveloped COSE Structures.
When the "receipts" header parameter is present, the verifier MUST
confirm that the associated VDS Verifiable Data Structure and VDPs Verifiable
Data Structure Proofs match entries present in the registries
established in this specification, including values added in
subsequent registrations.
Receipts MUST be tagged as COSE_Sign1.
The following definition from [RFC8610] is provided:
Signature_With_Receipt = /6.18(COSE_Sign1) #6.18(COSE_Sign1)
cose-label = int / text
cose-values = any
Protected_Header = {
* cose-label => cose-values
}
Unprotected_Header = {
&(receipts: 394) => [+ bstr .cbor Receipt]
* cose-label => cose-values
}
COSE_Sign1 = [
protected : bstr .cbor Protected_Header,
unprotected : Unprotected_Header,
payload : bstr / nil,
signature : bstr
]
Receipt = Receipt_For_Inclusion / Receipt_For_Consistency
; Note the proof formats shown here are for RFC9162_SHA256.
; Other VDSs Verifiable Data Structures may have different proof formats.
Receipt_For_Inclusion = /6.18(Signed_Inclusion_Proof) #6.18(Signed_Inclusion_Proof)
Signed_Inclusion_Proof = [
protected :
bstr .cbor RFC9162_SHA256_Inclusion_Protected_Header,
unprotected : RFC9162_SHA256_Inclusion_Unprotected_Header,
payload : bstr / nil,
signature : bstr
]
RFC9162_SHA256_Inclusion_Protected_Header = {
&(alg: 1) => int
&(vds: 395) => int
* cose-label => cose-values
}
RFC9162_SHA256_Inclusion_Unprotected_Header = {
&(vdp: 396) => RFC9162_SHA256_Verifiable_Inclusion_Proofs
* cose-label => cose-values
}
RFC9162_SHA256_Verifiable_Inclusion_Proofs = {
&(inclusion-proof: -1) => RFC9162_SHA256_Inclusion_Proofs
}
RFC9162_SHA256_Inclusion_Proofs = [
+ RFC9162_SHA256_Inclusion_Proof
]
RFC9162_SHA256_Inclusion_Proof = bstr .cbor [
tree_size: uint,
leaf_index: uint,
inclusion_path: [ + bstr ]
]
Receipt_For_Consistency = /6.18(Signed_Consistency_Proof) #6.18(Signed_Consistency_Proof)
Signed_Consistency_Proof = [
protected :
bstr .cbor RFC9162_SHA256_Consistency_Protected_Header,
unprotected : RFC9162_SHA256_Consistency_Unprotected_Header,
payload : bstr / nil, ; Newer Merkle Tree root
signature : bstr
]
RFC9162_SHA256_Consistency_Protected_Header = {
&(alg: 1) => int,
&(vds: 395) => int,
* cose-label => cose-values
}
RFC9162_SHA256_Consistency_Unprotected_Header = {
&(vdp: 396) => RFC9162_SHA256_Verifiable_Consistency_Proofs
* cose-label => cose-values
}
RFC9162_SHA256_Verifiable_Consistency_Proofs = {
&(consistency-proof: -2) => RFC9162_SHA256_Consistency_Proofs
}
RFC9162_SHA256_Consistency_Proofs = [
+ RFC9162_SHA256_Consistency_Proof
]
RFC9162_SHA256_Consistency_Proof = bstr .cbor [
tree_size_1: uint,
tree_size_2: uint,
consistency_path: [ + bstr ]
]
Figure 1: CDDL for a COSE_Sign1 with Attached Receipts
The following informative EDN is provided:
/ cose-sign1 / 18([
/ protected / <<{
/ kid / 4 : h'bc297b51...e4edf0de',
/ algorithm / 1 : -7, / ES256
}>>,
/ unprotected / {
/ receipts / 394 : [
<</ cose-sign1 / 18([
/ protected / <<{
/ kid / 4 : h'abcdef12...34567890',
/ algorithm / 1 : -7, / ES256
/ vds / 395 : 1, / RFC9162_SHA256
}>>,
/ unprotected / {
/ proofs / 396 : {
/ inclusion / -1 : [
<<[
/ size / 9, / leaf / 8,
/ inclusion path /
h'7558a95f...e02e35d6'
]>>
],
},
},
/ payload / null,
/ signature / h'02d227ed...ccd3774f'
])>>,
<</ cose-sign1 / 18([
/ protected / <<{
/ kid / 4 : h'abcdef12...34567890',
/ algorithm / 1 : -7, / ES256
/ vds / 395 : 1, / RFC9162_SHA256
}>>,
/ unprotected / {
/ proofs / 396 : {
/ inclusion / -1 : [
<<[
/ size / 6, / leaf / 5,
/ inclusion path /
[ h'9352f974...4ffa7ce0',
h'54806f32...f007ea06' ]
]>>
],
},
},
/ payload / null,
/ signature / h'36581f38...a5581960'
])>>
],
},
/ payload / h'0167c57c...deeed6d4',
/ signature / h'2544f2ed...5840893b'
])
Figure 2: An Example COSE Signature with Multiple Receipts
The specific structure of COSE Receipts is dependent on the structure
of the COSE_Sign1 payload and the VDPs Verifiable Data Structure Proofs
contained in the COSE_Sign1 unprotected header. The CDDL definition
for VDPs Verifiable Data Structure Proofs is specific to each
VDS. Verifiable
Data Structure. This document describes proofs for RFC9162_SHA256 in
the following sections.
4.4. Profiles
New VDSs Verifiable Data Structures can require the definition of a
profile. The payload in such definitions SHOULD be detached.
Detached payloads force verifiers to recompute the root from the
proof and protect against implementation errors where the signature
is verified but the payload is incompatible with the proof. Profiles
of proof signatures that define additional protected header
parameters are encouraged to make their presence mandatory to ensure
that claims are processed with their intended semantics. One way to
include this information in the COSE structure is use of the "typ"
(type) header parameter; see [RFC9596] and the similar guidance
provided in [RFC9597].
4.4.1. Registration Requirements
Each VDS Verifiable Data Structure specification applying for inclusion
in this registry MUST define how to encode the VDS Verifiable Data
Structure identifier and its Proof Types in CBOR. Each specification
MUST define how to produce and consume the supported Proof Types.
See Section 5 as an example.
Where a specification supports a choice of hash algorithm, a separate
IANA registration must be made for each supported algorithm. For
example, to provide support for SHA256 and SHA3_256 with Merkle
inclusion proofs and Merkle consistency proofs defined, respectively,
in Section 2.1.3 of [RFC9162] and Section 2.1.4 of [RFC9162], both
"RFC9162_SHA256" and "RFC9162_SHA3_256" require entries in the
relevant IANA registries. This document only defines
"RFC9162_SHA256".
5. RFC9162_SHA256
This section defines how the data structure described in Section 2.1
of [RFC9162] is mapped to the terminology defined in this document,
using [RFC8949] and [RFC9053].
5.1. Verifiable Data Structure
The integer identifier for this VDS Verifiable Data Structure is 1. The
string identifier for this VDS Verifiable Data Structure is
"RFC9162_SHA256", a Merkle Tree where SHA256 is used as the hash
algorithm (see Table 2). See Section 2.1.1 of [RFC9162] for a
complete description of this VDS. Verifiable Data Structure.
5.2. Inclusion Proof
See Section 2.1.3.1 of [RFC9162] for a complete description of this
VDP
Verifiable Data Structure Proof Type.
The CBOR representation of an inclusion proof for RFC9162_SHA256 is:
inclusion-proof = bstr .cbor [
; tree size at current Merkle Tree root
tree-size: uint
; index of leaf in tree
leaf-index: uint
; path from leaf to current Merkle Tree root
inclusion-path: [ + bstr ]
]
Figure 3: CBOR-Encoded Inclusion Proof for RFC9162_SHA256
The term leaf-index is used for alignment with the use established in
Section 2.1.3.2 of [RFC9162].
Note that [RFC9162] defines inclusion proofs only for leaf nodes, and
that:
| If leaf_index is greater than or equal to tree_size, then fail the
| proof verification.
The identifying index of a leaf node is relative to all nodes in the
tree size for which the proof was obtained.
5.2.1. Receipt of Inclusion
In a signed proof, the payload is the Merkle Tree root that
corresponds to the log at size tree-size. The protected header for
an RFC9162_SHA256 inclusion proof signature is:
protected-header-map = {
&(alg: 1) => int
&(vds: 395) => int
* cose-label => cose-value
}
Figure 4: Protected Header for a Receipt of Inclusion
alg (label: 1): REQUIRED. Signature algorithm identifier. Value
type: int.
vds (label: 395): REQUIRED. VDS Verifiable Data Structure algorithm
identifier. Value type: int.
The unprotected header for an RFC9162_SHA256 inclusion proof
signature is:
inclusion-proofs = [ + inclusion-proof ]
verifiable-proofs = {
&(inclusion-proof: -1) => inclusion-proofs
}
unprotected-header-map = {
&(vdp: 396) => verifiable-proofs
* cose-label => cose-value
}
Figure 5: A VDP Verifiable Data Structure Proofs in an Unprotected Header
vdp (label: 396): REQUIRED. Verifiable Data Structure Proofs.
Value type: Map.
inclusion-proof (label: -1): REQUIRED. Inclusion proofs. Value
type: Array of bstr.
The payload of an RFC9162_SHA256 inclusion proof signature is the
Merkle Tree Hash as defined in [RFC9162].
An EDN example for a Receipt containing an inclusion proof for
RFC9162_SHA256 with a detached payload (see Section 4.4) is:
/ cose-sign1 / 18([
/ protected / <<{
/ algorithm / 1 : -7, / ES256
/ vds / 395 : 1, / RFC9162_SHA256
}>>,
/ unprotected / {
/ proofs / 396 : {
/ inclusion / -1 : [
<<[
/ size / 20, / leaf / 17,
/ inclusion path /
[ h'fc9f050f...221c92cb',
h'bd0136ad...6b28cf21',
h'd68af9d6...93b1632b' ]
]>>
],
},
},
/ payload / null,
/ signature / h'de24f0cc...9a5ade89'
])
Figure 6: Receipt of Inclusion
The VDS in the protected header is necessary to understand the
inclusion proof structure in the unprotected header.
The inclusion proof and signature are verified in order. First, the
verifier applies the inclusion proof to a possible entry (set member)
bytes. If this process fails, the inclusion proof may have been
tampered with. If this process succeeds, the result is a Merkle Tree
root, which is then attached as the COSE_Sign1 payload. Second, the
verifier checks the signature of the COSE_Sign1. If the resulting
signature can be verified, the Receipt has proved inclusion of the
entry in the VDS. Verifiable Data Structure. If the resulting signature
cannot be verified, the signature may have been tampered with.
5.3. Consistency Proof
See Section 2.1.4.1 of [RFC9162] for a complete description of this
VDP
Verifiable Data Structure Proof Type.
The cbor CBOR representation of a consistency proof for RFC9162_SHA256 is:
consistency-proof = bstr .cbor [
; older Merkle Tree size
tree-size-1: uint
; newer Merkle Tree size
tree-size-2: uint
; path from older Merkle Tree to newer Merkle Tree
consistency-path: [ + bstr ]
]
Figure 7: CBOR-Encoded Consistency Proof for RFC9162_SHA256
5.3.1. Receipt of Consistency
In a signed consistency proof, the newer Merkle Tree root (proven to
be consistent with an older Merkle Tree root) is a detached payload
and corresponds to the log at size tree-size-2.
The protected header for an RFC9162_SHA256 consistency proof
signature is:
protected-header-map = {
&(alg: 1) => int
&(vds: 395) => int
* cose-label => cose-value
}
Figure 8: Protected Header for a Receipt of Consistency
alg (label: 1): REQUIRED. Signature algorithm identifier. Value
type: int.
vds (label: 395): REQUIRED. VDS Verifiable Data Structure algorithm
identifier. Value type: int.
The unprotected header for an RFC9162_SHA256 consistency proof
signature is:
consistency-proofs = [ + consistency-proof ]
verifiable-proofs = {
&(consistency-proof: -2) => consistency-proofs
}
unprotected-header-map = {
&(vdp: 396) => verifiable-proofs
* cose-label => cose-value
}
vdp (label: 396): REQUIRED. VDPs. Verifiable Data Structure Proofs.
Value type: Map.
consistency-proof (label: -2): REQUIRED. Consistency proofs. Value
type: Array of bstr.
The payload of an RFC9162_SHA256 consistency proof signature is: The
newer Merkle Tree Hash as defined in [RFC9162].
An EDN example for a Receipt containing a consistency proof for
RFC9162_SHA256 with a detached payload (see Section 4.4) is:
/ cose-sign1 / 18([
/ protected / <<{
/ algorithm / 1 : -7, / ES256
/ vds / 395 : 1, / RFC9162_SHA256
}>>,
/ unprotected / {
/ proofs / 396 : {
/ consistency / -2 : [
<<[
/ old / 20, / new / 104,
/ consistency path /
h'e5b3e764...c4a813bc',
h'87e8a084...4f529f69',
h'f712f76d...92a0ff36',
h'd68af9d6...93b1632b',
h'249efab6...b7614ccd',
h'85dd6293...38914dc1'
]>>
],
},
},
/ payload / null,
/ signature / h'94469f73...52de67a1'
])
Figure 9: Example Consistency Receipt
The VDS in the protected header is necessary to understand the
consistency proof structure in the unprotected header.
The signature and consistency proof are verified in order.
First, the verifier checks the signature on the COSE_Sign1. If the
verification fails, the consistency proof is not checked. Second,
the consistency proof is checked by applying a previous inclusion
proof to the consistency proof. If the verification fails, the
append-only property of the VDS Verifiable Data Structure is not assured.
This approach is specific to RFC9162_SHA256; different VDSs Verifiable
Data Structures may not support consistency proofs. It is
recommended that implementations return a single boolean result for
Receipt-verification operations to reduce the chance of accepting a
valid signature over an invalid consistency proof.
6. Privacy Considerations
6.1. Log Length
Some structures and proofs leak the size of the log at the time of
inclusion. In the case that a log only stores certain kinds of
information, this can reveal details that could impact reputation.
For example, if a transparency log only stored breach notices, a
receipt for a breach notice would reveal the number of previous
breaches at the time the notice was made transparent.
6.2. Header Parameters
Additional header parameters can reveal information about the
transparency service or its log entries. The receipt producer MUST
perform a privacy analysis for all mandatory fields in profiles based
on this specification.
7. Security Considerations
See the Security Considerations sections of:
* [RFC9162]
* [RFC9053]
7.1. Choice of Signature Algorithms
A security analysis ought to be performed to ensure that the digital
signature algorithm alg has the appropriate strength to secure
receipts.
It is recommended to select signature algorithms that share
cryptographic components with the VDS Verifiable Data Structure used; for
example, both RFC9162_SHA256 and ES256 depend on the SHA256 hash
function.
7.2. Validity Period
In some cases, receipts MAY include strict validity periods, for
example, activation not too far in the future or expiration not too
far in the past. See the iat, nbf, and exp claims in [RFC8392] for
one way to accomplish this. The details of expressing validity
periods are out of scope for this document.
7.3. Status Updates
In some cases, receipts should be "revocable" or "suspendable" after
being issued, regardless of their validity period. The details of
expressing statuses are out of scope for this document.
8. IANA Considerations
8.1. COSE Header Parameter
IANA has added the COSE header parameters defined in Section 2, and
as listed in Table 1, to the "COSE Header Parameters" subregistry
[IANA.cose_header-parameters] in the "CBOR Object Signing and
Encryption (COSE)" registry group. These COSE header parameters fall
in the 'Integer values from 256 to 65535' range (with a Specification
Required registration procedure (see [RFC8126])). The Value Registry
listed for "vds" is the "COSE Verifiable Data Structure Algorithm"
subregistry. The map labels in the "vdp" are assigned from the "COSE
Verifiable Data Structure Proofs" subregistry.
+==========+=======+=======+============+==============+===========+
| Name | Label | Value | Value | Description | Reference |
| | | Type | Registry | | |
+==========+=======+=======+============+==============+===========+
| receipts | 394 | array | | Priority | RFC 9942, |
| | | | | ordered | Section 2 |
| | | | | sequence of | |
| | | | | CBOR encoded | |
| | | | | Receipts | |
+----------+-------+-------+------------+--------------+-----------+
| vds | 395 | int | COSE | Algorithm | RFC 9942, |
| | | | Verifiable | identifier | Section 2 |
| | | | Data | for | |
| | | | Structure | Verifiable | |
| | | | | Data | |
| | | | | Structures | |
| | | | | that is used | |
| | | | | to produce | |
| | | | | Verifiable | |
| | | | | Data | |
| | | | | Structure | |
| | | | | Proofs | |
+----------+-------+-------+------------+--------------+-----------+
| vdp | 396 | map | map key in | Location for | RFC 9942, |
| | | | COSE | Verifiable | Section 2 |
| | | | Verifiable | Data | |
| | | | Data | Structure | |
| | | | Structure | Proofs in | |
| | | | Proofs | COSE Header | |
| | | | | Parameters | |
+----------+-------+-------+------------+--------------+-----------+
Table 1: Newly Registered COSE Header Parameters
8.2. VDS Verifiable Data Structure Registries
IANA has established the "COSE Verifiable Data Structure Algorithms" and
"COSE Verifiable Data Structure Proofs" subregistries under a
Specification Required policy as described in Section 4.6 of
[RFC8126].
8.2.1. Expert Review
Expert reviewers (see [RFC8126]) should take into consideration the
following points:
* Experts are advised to assign the next available positive integer
for VDSs. Verifiable Data Structures.
* Point squatting should be discouraged. Reviewers are encouraged
to get sufficient information for registration requests to ensure
that the usage is not going to duplicate one that is already
registered and that the point is likely to be used in deployments.
* Specifications are required for all point assignments. early Early
allocation is permissible, see Section 2 of [RFC7120].
* It is not permissible to assign points in the "COSE COSE Verifiable Data
Structure Algorithms" registry algorithms for which no corresponding
entry in the "COSE COSE Verifiable
Data Structure Proofs" registry Proofs entry exists, and vice versa.
* The change controller for related registrations of structures and
proofs should be the same.
8.2.2. Templates and Initial Contents
8.2.2.1. COSE Verifiable Data Structure Algorithms Registry
Registration Template:
Name:
This is a descriptive name for the VDS Verifiable Data Structure
that enables easier reference to the item.
Value:
This is the value used to identify the VDS. Verifiable Data
Structure.
Description:
This field contains a brief description of the VDS. Verifiable Data
Structure.
Reference:
This contains a pointer to the public specification for the
VDS.
Verifiable Data Structure.
Change Controller:
For Standards Track RFCs, list the "IETF". For others, give
the name of the responsible party. Other details (e.g., postal
address, email address, home page URI) may also be included.
+================+=======+===============+============+===========+
| Name | Value | Description | Change | Reference |
| | | | Controller | |
+================+=======+===============+============+===========+
| Reserved | 0 | Reserved | | RFC 9942 |
+----------------+-------+---------------+------------+-----------+
| RFC9162_SHA256 | 1 | SHA256 Binary | IETF | Section |
| | | Merkle Tree | | 2.1 of |
| | | | | [RFC9162] |
+----------------+-------+---------------+------------+-----------+
Table 2: COSE Verifiable Data Structure Algorithms Registry Initial
Registry Contents
8.2.2.2. COSE Verifiable Data Structure Proofs Registry
Registration Template:
Verifiable Data Structure:
This value used identifies the related VDS. Verifiable Data
Structure.
Name:
This is a descriptive name for the Proof Type that enables
easier reference to the item.
Label:
This is the value used to identify the VDP Verifiable Data
Structure Proof Type.
CBOR Type:
This contains the CBOR type for the value portion of the label.
Description:
This field contains a brief description of the Proof Type.
Reference:
This contains a pointer to the public specification for the
Proof Type.
Change Controller:
For Standards Track RFCs, list the "IETF". For others, give
the name of the responsible party. Other details (e.g., postal
address, email address, home page URI) may also be included.
+==========+===========+=====+=====+===========+==========+=========+
|Verifiable|Name |Label|CBOR |Description|Change |Reference|
|Data | | |Type | |Controller| |
|Structure | | | | | | |
+==========+===========+=====+=====+===========+==========+=========+
|1 |inclusion |-1 |array|Proof of |IETF |RFC 9942,|
| |proofs | |(of |inclusion | |Section |
| | | |bstr)| | |5.2 |
+----------+-----------+-----+-----+-----------+----------+---------+
|1 |consistency|-2 |array|Proof of |IETF |RFC 9942,|
| |proofs | |(of |append-only| |Section |
| | | |bstr)|property | |5.3 |
+----------+-----------+-----+-----+-----------+----------+---------+
Table 3: COSE Verifiable Data Structure Proofs Registry Initial Registry
Contents
9. References
9.1. Normative References
[IANA.cose_header-parameters]
IANA, "COSE Header Parameters",
<https://www.iana.org/assignments/cose>.
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119,
DOI 10.17487/RFC2119, March 1997,
<https://www.rfc-editor.org/info/rfc2119>.
[RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC
2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174,
May 2017, <https://www.rfc-editor.org/info/rfc8174>.
[RFC8610] Birkholz, H., Vigano, C., and C. Bormann, "Concise Data
Definition Language (CDDL): A Notational Convention to
Express Concise Binary Object Representation (CBOR) and
JSON Data Structures", RFC 8610, DOI 10.17487/RFC8610,
June 2019, <https://www.rfc-editor.org/info/rfc8610>.
[RFC8949] Bormann, C. and P. Hoffman, "Concise Binary Object
Representation (CBOR)", STD 94, RFC 8949,
DOI 10.17487/RFC8949, December 2020,
<https://www.rfc-editor.org/info/rfc8949>.
[RFC9053] Schaad, J., "CBOR Object Signing and Encryption (COSE):
Initial Algorithms", RFC 9053, DOI 10.17487/RFC9053,
August 2022, <https://www.rfc-editor.org/info/rfc9053>.
[RFC9162] Laurie, B., Messeri, E., and R. Stradling, "Certificate
Transparency Version 2.0", RFC 9162, DOI 10.17487/RFC9162,
December 2021, <https://www.rfc-editor.org/info/rfc9162>.
[RFC9596] Jones, M.B. and O. Steele, "CBOR Object Signing and
Encryption (COSE) "typ" (type) Header Parameter",
RFC 9596, DOI 10.17487/RFC9596, June 2024,
<https://www.rfc-editor.org/info/rfc9596>.
[RFC9597] Looker, T. and M.B. Jones, "CBOR Web Token (CWT) Claims in
COSE Headers", RFC 9597, DOI 10.17487/RFC9597, June 2024,
<https://www.rfc-editor.org/info/rfc9597>.
[STD96] Internet Standard 96,
<https://www.rfc-editor.org/info/std96>.
At the time of writing, this STD comprises the following:
Schaad, J., "CBOR Object Signing and Encryption (COSE):
Structures and Process", STD 96, RFC 9052,
DOI 10.17487/RFC9052, August 2022,
<https://www.rfc-editor.org/info/rfc9052>.
Schaad, J., "CBOR Object Signing and Encryption (COSE):
Countersignatures", STD 96, RFC 9338,
DOI 10.17487/RFC9338, December 2022,
<https://www.rfc-editor.org/info/rfc9338>.
9.2. Informative References
[CBOR-EDN] Bormann, C., "CBOR Extended Diagnostic Notation (EDN)",
Work in Progress, Internet-Draft, draft-ietf-cbor-edn-
literals-22, 6 April 2026,
<https://datatracker.ietf.org/doc/html/draft-ietf-cbor-
edn-literals-22>.
[RFC7120] Cotton, M., "Early IANA Allocation of Standards Track Code
Points", BCP 100, RFC 7120, DOI 10.17487/RFC7120, January
2014, <https://www.rfc-editor.org/info/rfc7120>.
[RFC8126] Cotton, M., Leiba, B., and T. Narten, "Guidelines for
Writing an IANA Considerations Section in RFCs", BCP 26,
RFC 8126, DOI 10.17487/RFC8126, June 2017,
<https://www.rfc-editor.org/info/rfc8126>.
[RFC8392] Jones, M., Wahlstroem, E., Erdtman, S., and H. Tschofenig,
"CBOR Web Token (CWT)", RFC 8392, DOI 10.17487/RFC8392,
May 2018, <https://www.rfc-editor.org/info/rfc8392>.
[RFC9052] Schaad, J., "CBOR Object Signing and Encryption (COSE):
Structures and Process", STD 96, RFC 9052,
DOI 10.17487/RFC9052, August 2022,
<https://www.rfc-editor.org/info/rfc9052>.
Acknowledgements
We would like to thank Maik Riechert, Jon Geater, Michael B. Jones,
Mike Prorock, Ilari Liusvaara, and Amaury Chamayou for their
contributions (some of which substantial) to this document and to the
initial set of implementations.
Contributors
Amaury Chamayou
Microsoft
United Kingdom
Email: amaury.chamayou@microsoft.com
Steve Lasker
Email: stevenlasker@hotmail.com
Robert Martin
MITRE Corporation
United States of America
Email: ramartin@mitre.org
Monty Wiseman
United States of America
Email: mwiseman32@acm.org
Roy Williams
United States of America
Email: roywill@msn.com
Authors' Addresses
Orie Steele
Tradeverifyd
United States of America
Email: orie@or13.io
Henk Birkholz
Fraunhofer SIT
Rheinstrasse 75
64295 Darmstadt
Germany
Email: henk.birkholz@ietf.contact
Antoine Delignat-Lavaud
Microsoft
United Kingdom
Email: antdl@microsoft.com
Cédric Fournet
Microsoft
United Kingdom
Email: fournet@microsoft.com