Message Digest for DNS ZonesVerisign12061 Bluemont WayRestonVA20190United States of America+1 703 948-3200dwessels@verisign.comhttps://verisign.comVerisign12061 Bluemont WayRestonVA20190United States of America+1 703 948-3200pbarber@verisign.comhttps://verisign.comAmazonmatweinb@amazon.comhttps://amazon.comGoogle1600 Amphitheatre ParkwayMountain ViewCA94043United States of Americawarren@kumari.netUSC/ISIP.O. Box 382DavisCA95617United States of Americaietf@hardakers.net
General
Internet Engineering Task ForceDNSDNSSECChecksumHashZone Transfer
This document describes a protocol and new DNS Resource Record that
provides a cryptographic message digest over DNS zone data at rest.
The ZONEMD Resource Record conveys the digest data in the zone itself.
When used in combination with DNSSEC, ZONEMD allows recipients to
verify the zone contents for data integrity and origin authenticity.
This provides assurance that received zone data matches published
data, regardless of how the zone data has been transmitted and
received. When used without DNSSEC, ZONEMD functions as a checksum,
guarding only against unintentional changes.
ZONEMD does not replace DNSSEC:
DNSSEC protects individual RRsets (DNS data with
fine granularity), whereas ZONEMD protects a zone's data
as a whole, whether consumed by authoritative name
servers, recursive name servers, or any other applications.
As specified herein, ZONEMD is impractical
for large, dynamic zones due to the time and resources
required for digest calculation.
However, the ZONEMD record is extensible
so that new digest schemes may be added in the future to support large, dynamic
zones.
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
.
Copyright Notice
Copyright (c) 2021 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
() in effect on the date of
publication of this document. Please review these documents
carefully, as they describe your rights and restrictions with
respect to this document. Code Components extracted from this
document must include Simplified BSD License text as described in
Section 4.e of the Trust Legal Provisions and are provided without
warranty as described in the Simplified BSD License.
Table of Contents
. Introduction
. Motivation
. Alternative Approaches
. Design Overview
. Use Cases
. Root Zone
. Providers, Secondaries, and Anycast
. Response Policy Zones
. Centralized Zone Data Service
. General Purpose Comparison Check
. Terminology
. The ZONEMD Resource Record
. Non-apex ZONEMD Records
. ZONEMD RDATA Wire Format
. The Serial Field
. The Scheme Field
. The Hash Algorithm Field
. The Digest Field
. ZONEMD Presentation Format
. ZONEMD Example
. Including ZONEMD RRs in a Zone
. Calculating the Digest
. Add ZONEMD Placeholder
. Optionally, Sign the Zone
. Scheme-Specific Processing
. The SIMPLE Scheme
. SIMPLE Scheme Inclusion/Exclusion Rules
. SIMPLE Scheme Digest Calculation
. Update ZONEMD RR
. Verifying Zone Digest
. IANA Considerations
. ZONEMD RRtype
. ZONEMD Scheme
. ZONEMD Hash Algorithms
. Security Considerations
. Using Zone Digest without DNSSEC
. Attacks against the Zone Digest
. Use of Multiple ZONEMD Hash Algorithms
. DNSSEC Timing Considerations
. Attacks Utilizing ZONEMD Queries
. Resilience and Fragility
. Performance Considerations
. SIMPLE SHA384
. Privacy Considerations
. References
. Normative References
. Informative References
. Example Zones with Digests
. Simple EXAMPLE Zone
. Complex EXAMPLE Zone
. EXAMPLE Zone with Multiple Digests
. The URI.ARPA Zone
. The ROOT-SERVERS.NET Zone
. Implementation Status
. Authors' Implementation
. Shane Kerr's Implementation
. NIC Chile Lab's Implementation
Acknowledgments
Authors' Addresses
Introduction
In the DNS, a zone is the collection of authoritative resource records
(RRs) sharing a common origin (). Zones are often stored as files in the so-called
"master file format" (). Zones
are generally distributed among name servers using the zone transfer
(AXFR) () and incremental zone
transfer (IXFR) () protocols.
They can also be distributed outside of the DNS with any file transfer
protocol such as FTP, HTTP, and rsync, or even as email attachments.
Currently, there is no standard way to compute a hash or message
digest for a stand-alone zone.
This document specifies an RR type that provides a cryptographic
message digest of the data in a zone. It allows a receiver of the
zone to verify the zone's integrity and authenticity when used in
combination with DNSSEC. The digest RR is a part of the zone itself,
allowing verification of the zone, no matter how it is transmitted.
The digest uses the wire format of zone data in a canonical ordering.
Thus, it is independent of presentation format such as whitespace,
capitalization, and comments.
This specification is OPTIONAL to implement by both publishers
and consumers of zone data.
Motivation
The primary motivation for this protocol enhancement is the desire
to verify the data integrity and origin authenticity of a
stand-alone zone, regardless of how it is transmitted. A consumer
of zone data should be able to verify that it is as published by the
zone operator.
Note, however, that integrity and authenticity can only be
assured when the zone is signed.
DNSSEC provides three strong security guarantees relevant
to this protocol:
whether or not to expect DNSSEC
records in the zone,
whether or not to expect a ZONEMD record in a signed zone, and
whether or not the ZONEMD record has been altered since it was signed.
A secondary motivation is to provide the equivalent of a checksum,
allowing a zone recipient to check for unintended changes and
operational errors such as accidental truncation.
Alternative Approaches
One approach to preventing data tampering and corruption is to
secure the distribution channel. The DNS has a number of features
that are already used for channel security. Perhaps the most widely
used is DNS transaction signatures (TSIGs) (). A TSIG uses shared secret keys and a message
digest to protect individual query and response messages. It is
generally used to authenticate and validate UPDATE (), AXFR (), and IXFR () messages.
DNS Request and Transaction Signatures (SIG(0)) () is another protocol extension
that authenticates individual DNS transactions. Whereas SIG records
normally cover specific RR types, SIG(0) is used to sign an entire
DNS message. Unlike TSIG, SIG(0) uses public key cryptography
rather than shared secrets.
The Transport Layer Security protocol suite also provides channel
security. The DPRIVE Working Group is in the process of specifying
DNS Zone Transfer-over-TLS (). One can
also easily imagine the distribution of zones over HTTPS-enabled web
servers as well as DNS-over-HTTPS ().
Unfortunately, the protections provided by these channel security
techniques are (in practice) ephemeral and are not retained after
the data transfer is complete. They ensure that the client receives
the data from the expected server and that the data sent by the
server is not modified during transmission. However, they do not
guarantee that the server transmits the data as originally published
and do not provide any methods to verify data that is read after
transmission is complete. For example, a name server loading saved
zone data upon restart cannot guarantee that the on-disk data has
not been modified. Such modification could be the result of an
accidental corruption of the file or perhaps an incomplete saving of
the file (). For
these reasons, it is preferable to protect the integrity of the data
itself.
Why not simply rely on DNSSEC, which provides certain data security
guarantees? For zones that are signed, a recipient could validate
all of the signed RRsets. Additionally, denial-of-existence records
prove that RRsets have not been added or removed. However,
delegations (non-apex NS records) are not signed by DNSSEC and
neither are any glue records. ZONEMD protects the integrity of
delegation, glue, and other records that are not otherwise covered
by DNSSEC. Furthermore, zones that employ NSEC3 with Opt-Out () are susceptible to the removal
or addition of names between the signed nodes. Whereas DNSSEC
primarily protects consumers of DNS response messages, this protocol
protects consumers of zones.
There are existing tools and protocols that provide data security,
such as OpenPGP () and
S/MIME (). In fact, the
internic.net site publishes Pretty Good Privacy (PGP) signatures
alongside the root zone and other files available there. However,
this is a detached signature with no strong association to the
corresponding zone file other than its timestamp.
Attached signatures are of course possible, but these necessarily change the
format of the file being distributed; a zone signed with OpenPGP or S/MIME
no longer looks like a DNS zone and could not directly be loaded into a name
server. Once loaded, the signature data is lost, so it cannot be further
propagated.
It seems the desire for data security in DNS zones was envisioned
as far back as 1997.
is an obsoleted specification
of the first generation DNSSEC Security Extensions. It
describes a zone transfer signature, identified as the AXFR SIG, which
is similar to the technique proposed by this document.
That is, it proposes ordering all (signed) RRsets in a zone,
hashing their contents, and then signing the zone hash.
The AXFR SIG is described only for use during zone
transfers. It did not postulate the need to validate
zone data distributed outside of the DNS.
Furthermore, its successor, , omits the AXFR SIG while at the same time introducing an
IXFR SIG. (Note: RFC 2535 was obsoleted by , , and .)
Design Overview
This document specifies a new Resource Record type
to convey a message digest of the content of a zone.
The digest is calculated at the time of zone publication.
If the zone is signed with DNSSEC, any
modifications of the digest can be detected. The procedures for
digest calculation and DNSSEC signing are similar. Both require
data to be processed in a well-defined order and format.
It may be possible to perform DNSSEC signing and
digest calculation in parallel.
The zone digest is designed to be used on zones that
have infrequent updates. As specified herein,
the digest is recalculated over the entire zone
content each time the zone is updated. This specification does not provide
an efficient mechanism for updating the digest on incremental updates of zone
data. It is, however, extensible so that
future schemes may be defined to support efficient incremental
digest updates.
It is expected that verification of a zone digest will be
implemented in name server software. That is, a name server
can verify the zone data it was given and refuse to serve a
zone that fails verification. For signed zones, the name
server needs a trust anchor to perform DNSSEC validation.
For signed non-root zones, the name server may need to send
queries to validate a chain of trust. Digest verification
could also be performed externally.
Use CasesRoot Zone
The root zone () is one of
the most widely distributed DNS zones on the Internet, served by
more than 1000 separate instances () at the time of this writing. Additionally,
many organizations configure their own name servers to serve the
root zone locally. Reasons for doing so include privacy and
reduced access time.
describes one way to do this. As the root zone spreads beyond its
traditional deployment boundaries, the verification of the
completeness of the zone contents becomes more important.
Providers, Secondaries, and Anycast
Since its very early days, the developers of the DNS recognized
the importance of secondary name servers and service diversity.
However, modern DNS service has complex provisioning that includes
multiple third-party providers () and hundreds of anycast instances (). Instead of a simple
primary-to-secondary zone distribution system, today it is
possible to have multiple levels, multiple parties, and multiple
protocols involved in the distribution of zone data. This
complexity introduces new places for problems to arise. The zone
digest protects the integrity of data that flows through such
systems.
Response Policy Zones
A Response Policy Zone (RPZ) is "a mechanism to introduce a
customized policy in Domain Name System servers, so that recursive
resolvers return possibly modified results" (). The policy information is carried inside
specially constructed DNS zones. A number of companies provide
RPZ feeds, which are consumed by name server and firewall
products. While RPZs can be signed with DNSSEC, the data is
not queried directly and would not be subject to DNSSEC
validation.
Centralized Zone Data Service
ICANN operates the Centralized Zone Data Service (), which is a repository of
top-level domain zone files. Users that have been granted access
are then able to download zone data. Adding a zone digest to
these would provide CZDS users with assurances that the data has
not been modified between origination and retrieval. Note that
ZONEMD could be added to zone data supplied to CZDS without
requiring it to be present in the zone data served by production
name servers, since the digest is inherently attached to the
specific copy of the zone.
General Purpose Comparison Check
Since the zone digest calculation does not depend on presentation
format, it could be used to compare multiple copies of
a zone received from different sources, or copies
generated by different processes. In this case, it serves
as a checksum and can be useful even for unsigned zones.
Terminology
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 when, and only when, they appear in all capitals,
as shown here.
The terms Private Use, Reserved, Unassigned, and Specification
Required are to be interpreted as defined in .
The ZONEMD Resource Record
This section describes the ZONEMD Resource Record, including its fields, wire format, and presentation format.
The Type value for the ZONEMD RR is 63.
The ZONEMD RR is class independent.
The RDATA of the resource record consists of four fields: Serial, Scheme, Hash Algorithm, and Digest.
Non-apex ZONEMD Records
This document specifies ZONEMD RRs located at the
zone apex. Non-apex ZONEMD RRs are not forbidden, but
have no meaning in this specification.
Non-apex ZONEMD RRs MUST NOT be used for verification.
During digest calculation,
non-apex ZONEMD RRs are treated as ordinary RRs.
They are digested as is, and the RR is not replaced
by a placeholder RR.
Unless explicitly stated otherwise, "ZONEMD" always refers
to apex records throughout this document.
ZONEMD RDATA Wire FormatThe ZONEMD RDATA wire format is encoded as follows:
1 1 1 1 1 1 1 1 1 1 2 2 2 2 2 2 2 2 2 2 3 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Serial |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Scheme |Hash Algorithm | |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |
| Digest |
/ /
/ /
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
The Serial Field
The Serial field is a 32-bit unsigned integer in network byte
order. It is the serial number from the zone's SOA record () for
which the zone digest was generated.
It is included here to clearly bind the ZONEMD RR to a particular
version of the zone's content. Without the serial number, a
stand-alone ZONEMD digest has no obvious association to any
particular instance of a zone.
The Scheme Field
The Scheme field is an 8-bit unsigned integer that identifies
the methods by which data is collated and presented
as input to the hashing function.
Herein, SIMPLE, with Scheme value 1, is the only standardized
Scheme defined for ZONEMD records and it MUST be
supported by implementations. The "ZONEMD Schemes" registry is further
described in .
Scheme values 240-254 are allocated for Private Use.
The Hash Algorithm Field
The Hash Algorithm field is an 8-bit unsigned integer
that identifies the cryptographic hash algorithm
used to construct the digest.
Herein, SHA384 (), with
Hash Algorithm value 1, is the only standardized Hash Algorithm
defined for ZONEMD records that MUST be supported
by implementations. When SHA384 is used, the size of the Digest
field is 48 octets. The result of the SHA384 digest algorithm
MUST NOT be truncated, and the entire 48-octet
digest is published in the ZONEMD record.
SHA512 (), with Hash
Algorithm value 2, is also defined for ZONEMD records and
SHOULD be supported by implementations. When
SHA512 is used, the size of the Digest field is 64 octets. The
result of the SHA512 digest algorithm MUST NOT be
truncated, and the entire 64-octet digest is published in the
ZONEMD record.
Hash Algorithm values 240-254 are allocated for Private Use.
The "ZONEMD Hash Algorithms" registry
is further described in .
The Digest Field
The Digest field is a variable-length sequence of octets
containing the output of the hash algorithm.
The length of the Digest field is determined by deducting
the fixed size of the Serial, Scheme, and Hash Algorithm
fields from the RDATA size in the ZONEMD RR header.
The Digest field MUST NOT be shorter than 12
octets. Digests for the SHA384 and SHA512 hash algorithms
specified herein are never truncated. Digests for future hash
algorithms MAY be truncated but MUST NOT be truncated to a length that results in less than 96
bits (12 octets) of equivalent strength.
describes how to calculate the digest for a zone.
describes how to use the digest to
verify the contents of a zone.
ZONEMD Presentation Format
The presentation format of the RDATA portion is as follows:
The Serial field is represented as an unsigned decimal integer.
The Scheme field is represented as an unsigned decimal integer.
The Hash Algorithm field is represented as an unsigned decimal
integer.
The Digest is represented as a sequence of case-insensitive
hexadecimal digits. Whitespace is allowed within the hexadecimal
text.
ZONEMD Example
The following example shows a ZONEMD RR in presentation format:
example.com. 86400 IN ZONEMD 2018031500 1 1 (
FEBE3D4CE2EC2FFA4BA99D46CD69D6D29711E55217057BEE
7EB1A7B641A47BA7FED2DD5B97AE499FAFA4F22C6BD647DE )
Including ZONEMD RRs in a Zone
The zone operator chooses an appropriate hash algorithm and
scheme and includes the calculated zone digest in the apex
ZONEMD RRset.
The zone operator MAY choose any of the defined hash algorithms
and schemes, including the Private Use code points.
The ZONEMD RRset MAY contain multiple records to support algorithm
agility ().
When multiple ZONEMD RRs are present, each MUST
specify a unique Scheme and Hash Algorithm tuple. It is
RECOMMENDED that a zone include only one ZONEMD RR,
unless the zone operator is in the process of transitioning to a new
scheme or hash algorithm.
Calculating the Digest
The algorithm described in this section is designed for the
common case of offline DNSSEC signing.
Slight deviations may be permitted or necessary in other
situations, such as with unsigned zones or online DNSSEC signing.
Implementations that deviate from the described algorithm are
advised to ensure that it produces ZONEMD RRs, signatures,
and denial-of-existence records that are identical to the
ones generated by this procedure.
Add ZONEMD Placeholder
In preparation for calculating the zone digest(s), any existing ZONEMD records
(and covering RRSIGs)
at the zone apex
are first deleted.
Prior to calculation of the digest, and prior to signing with
DNSSEC, one or more placeholder ZONEMD records are added to the
zone apex. This
ensures that
denial-of-existence (NSEC, NSEC3) records are created correctly
if the zone is signed with DNSSEC. If placeholders were not added prior to
signing, the later addition of ZONEMD records would also require updating the
Type Bit Maps field of any apex NSEC/NSEC3 RRs, which then invalidates
the calculated digest value.
When multiple ZONEMD RRs are published in the zone, e.g.,
during an algorithm rollover, each MUST specify a unique Scheme
and Hash Algorithm tuple.
It is RECOMMENDED that the TTL of the ZONEMD record
match the TTL of the Start of Authority (SOA). However, the TTL of
the ZONEMD record may be safely ignored during verification in all
cases.
In the placeholder record, the Serial field is
set to the current SOA Serial.
The Scheme field is set to the value for the chosen collation scheme.
The Hash Algorithm field is set
to the value for the chosen hash algorithm.
Since apex ZONEMD records are excluded from digest calculation,
the value of the Digest field does not matter at this point
in the process.
Optionally, Sign the Zone
Following the addition of placeholder records, the zone may be
signed with DNSSEC. When the digest calculation is complete, and
the ZONEMD record is updated, the signature(s) for the ZONEMD RRset
MUST be recalculated and updated as well. Therefore,
the signer is not required to calculate a signature over the
placeholder record at this step in the process, but it is harmless
to do so.
Scheme-Specific Processing
Herein, only the SIMPLE collation scheme is defined.
Additional schemes may be defined in future updates to this document.
The SIMPLE Scheme
For the SIMPLE scheme, the digest is calculated over the zone as
a whole. This means that a change to a single RR in the zone
requires iterating over all RRs in the zone to recalculate
the digest. SIMPLE is a good choice for zones that are small
and/or stable, but it is probably not good for zones that are
large and/or dynamic.
Calculation of a zone digest requires RRs to be processed in a
consistent format and ordering. This specification uses DNSSEC's
canonical on-the-wire RR format (without name compression) and
ordering as specified in Sections , , and of with the additional provision that RRsets
having the same owner name MUST be numerically
ordered, in ascending order, by their numeric RR TYPE.
SIMPLE Scheme Inclusion/Exclusion Rules
When iterating over records in the zone, the following
inclusion/exclusion rules apply:
All records in the zone, including glue records,
MUST be included unless excluded by a subsequent
rule.
Occluded data () MUST be included.
If there are duplicate RRs with equal owner, class, type,
and RDATA, only one instance is included () and the duplicates
MUST be omitted.
The placeholder apex ZONEMD RR(s) MUST NOT be included.
If the zone is signed, DNSSEC RRs MUST be included, except:
The RRSIG covering the apex ZONEMD RRset MUST NOT be included
because the RRSIG will be updated after all digests have been calculated.
SIMPLE Scheme Digest Calculation
A zone digest using the SIMPLE scheme is calculated by
concatenating all RRs in the zone, in the format and order
described in
subject to the inclusion/exclusion rules described in , and then
applying the chosen hash algorithm:
digest = hash( RR(1) | RR(2) | RR(3) | ... )
where "|" denotes concatenation.
Update ZONEMD RR
The calculated zone digest is inserted into the placeholder ZONEMD
RR. Repeat for each digest if multiple digests are to be published.
If the zone is signed with DNSSEC, the RRSIG record(s) covering the ZONEMD
RRset MUST then be added or updated. Because the ZONEMD placeholder was added prior to signing,
the zone will already have the appropriate denial-of-existence (NSEC, NSEC3) records.
Some DNSSEC implementations (especially "online signing") might
update the SOA serial number whenever
a new signature is made. To preserve the calculated digest,
generation of a ZONEMD signature MUST NOT also result in
a change to the SOA serial number. The ZONEMD RR and the
matching SOA MUST be published at the same time.
Verifying Zone Digest
The recipient of a zone that has a ZONEMD RR verifies the zone by
calculating the digest as follows:
The
verifier MUST first determine whether or not to expect
DNSSEC records in the zone. By examining locally configured trust
anchors and, if necessary, querying for and validating Delegation Signer
(DS) RRs in the parent zone, the verifier knows whether or not the zone
to be verified should include DNSSEC keys and signatures. For zones
where signatures are not expected, or if DNSSEC validation is not
performed, digest verification continues at step below.
For zones where signatures are expected, the existence of the apex
ZONEMD record MUST be validated. If the DNSSEC
data proves the ZONEMD RRset does not exist, digest verification
cannot occur. If the DNSSEC data proves the ZONEMD does exist,
but is not found in the zone, digest verification MUST NOT be considered successful.
For zones where signatures are expected, the SOA and ZONEMD RRsets
MUST have valid signatures, chaining up to a trust
anchor. If DNSSEC validation of the SOA or ZONEMD RRsets fails,
digest verification MUST NOT be considered
successful.
When multiple ZONEMD RRs are present, each MUST
specify a unique Scheme and Hash Algorithm tuple. If the ZONEMD
RRset contains more than one RR with the same Scheme and Hash
Algorithm, digest verification for those ZONEMD RRs MUST NOT be considered successful.
Loop over all apex ZONEMD RRs and perform the following steps:
The
SOA Serial field MUST exactly match the ZONEMD Serial
field. If the fields do not match, digest verification MUST NOT be considered successful with this ZONEMD RR.
The Scheme field MUST be checked. If the
verifier does not support the given scheme, verification
MUST NOT be considered successful with this
ZONEMD RR.
The Hash Algorithm field MUST be checked. If
the verifier does not support the given hash algorithm,
verification MUST NOT be considered successful
with this ZONEMD RR.
The Digest field size MUST be checked. If the
size of the given Digest field is smaller than 12 octets, or
if the size is not equal to the size expected for the
corresponding Hash Algorithm, verification MUST NOT be considered successful with this ZONEMD RR.
The zone digest is computed over the zone data as described in
using the
Scheme and Hash Algorithm for the current ZONEMD RR.
The computed digest is compared to the received digest. If
the two digest values match, verification is considered
successful. Otherwise, verification MUST NOT
be considered successful for this ZONEMD RR.
Each time zone verification is performed, the verifier SHOULD
report the status as either successful or unsuccessful.
When unsuccessful, the verifier SHOULD report the reason(s) that
verification did not succeed.
IANA ConsiderationsZONEMD RRtype
This document defines a new DNS RR type, ZONEMD, whose
value 63 has been allocated by IANA from the "Resource
Record (RR) TYPEs" subregistry of the "Domain Name System
(DNS) Parameters" registry:
Type:
ZONEMD
Value:
63
Meaning:
Message Digest Over Zone Data
Reference:
[RFC8976]
ZONEMD Scheme
IANA has created a new subregistry in the "Domain Name
System (DNS) Parameters" registry as follows:
Registry Name:
ZONEMD Schemes
Registration Procedure:
Specification Required
Reference:
[RFC8976]
ZONEMD Scheme Registry
Value
Description
Mnemonic
Reference
0
Reserved
[RFC8976]
1
Simple ZONEMD collation
SIMPLE
[RFC8976]
2-239
Unassigned
240-254
Private Use
N/A
[RFC8976]
255
Reserved
[RFC8976]
ZONEMD Hash Algorithms
IANA has created a new subregistry in the "Domain Name
System (DNS) Parameters" registry as follows:
Registry Name:
ZONEMD Hash Algorithms
Registration Procedure:
Specification Required
Reference:
[RFC8976]
ZONEMD Hash Algorithms Registry
Value
Description
Mnemonic
Reference
0
Reserved
[RFC8976]
1
SHA-384
SHA384
[RFC8976]
2
SHA-512
SHA512
[RFC8976]
3-239
Unassigned
240-254
Private Use
N/A
[RFC8976]
255
Reserved
[RFC8976]
Security ConsiderationsUsing Zone Digest without DNSSEC
Users of ZONEMD with unsigned zones are advised that
it provides no real protection against attacks.
While zone digests can be used in the absence of
DNSSEC, this only provides protection against accidental
zone corruption such as transmission errors and truncation. When used in this
manner, it effectively serves only as a checksum.
For zones not signed with DNSSEC, an attacker
can make any zone modifications appear to be valid
by recomputing the Digest field of a ZONEMD RR.
Attacks against the Zone Digest
An attacker, whose goal is to modify zone content before it is used
by the victim, may consider a number of different approaches.
The attacker might perform a downgrade attack to an unsigned
zone. This is why talks about
determining whether or not to expect DNSSEC
signatures for the zone in step .
The attacker might perform a downgrade attack by removing
one or more ZONEMD records. Such a removal is detectable only with DNSSEC
validation and is why
talks about checking denial-of-existence
proofs in step
and signature validation in step .
The attacker might alter the Scheme, Hash Algorithm, or Digest fields
of the ZONEMD record. Such modifications are detectable
only with DNSSEC validation.
As stated in ,
cryptographic algorithms age and become weaker as cryptanalysis
techniques and computing resources improve with time. Implementors
and publishers of zone digests should anticipate the need for
algorithm agility on long timescales.
Use of Multiple ZONEMD Hash Algorithms
When a zone publishes multiple ZONEMD RRs, the overall security is
only as good as the weakest hash algorithm in use. For this reason,
recommends only publishing multiple ZONEMD RRs
when transitioning to a new scheme or hash algorithm. Once the transition
is complete, the old scheme or hash algorithm should be removed from
the ZONEMD RRset.
DNSSEC Timing Considerations
As with all DNSSEC signatures, the ability to perform signature
validation of a ZONEMD record is limited in time.
If the DS record(s) or trust anchors for the zone to be verified
are no longer available, the recipient cannot validate
the ZONEMD RRset.
This could happen even if the ZONEMD signature is still current
(not expired), since the zone's DS record(s)
may have been withdrawn following a Key Signing Key (KSK) rollover.
For zones where it may be important to validate a ZONEMD
RRset through its entire signature validity period, the zone
operator should ensure that KSK rollover timing takes this
into consideration.
Attacks Utilizing ZONEMD Queries
Nothing in this specification prevents clients from making,
and servers from responding to, ZONEMD queries.
Servers SHOULD NOT calculate zone digests dynamically (for
each query) as this can be used as a CPU resource exhaustion
attack.
ZONEMD responses could be used in
a distributed denial-of-service amplification attack.
The ZONEMD RR is moderately sized, much like the DS RR.
A single ZONEMD RR contributes approximately 65 to 95
octets to a DNS response for digest
types defined herein. Other RR types, such as DNS Public Key (DNSKEY), can result in larger
amplification effects.
Resilience and Fragility
ZONEMD is used to detect incomplete or corrupted zone data prior to
its use, thereby increasing resilience by not using corrupt data,
but also introduces some denial-of-service fragility by making good
data in a zone unavailable if some other data is missing or corrupt.
Publishers and consumers of zones containing ZONEMD records should
be aware of these trade-offs. While the intention is to secure the
zone data, misconfigurations or implementation bugs are generally
indistinguishable from intentional tampering and could lead to
service failures when verification is performed automatically.
Zone publishers may want to deploy ZONEMD gradually perhaps
by utilizing one of the Private Use hash algorithm code points listed
in . Similarly, recipients
may want to initially configure verification failures only as
a warning, and later as an error after gaining experience and
confidence with the feature.
Performance Considerations
This section is provided to make zone publishers aware of the
performance requirements and implications of including ZONEMD
RRs in a zone.
SIMPLE SHA384
As mentioned previously, the SIMPLE scheme may be
impractical for use in zones that are either large or
highly dynamic.
Zone publishers should carefully consider the use of ZONEMD
in such zones since it might cause consumers of zone data
(e.g., secondary name servers) to expend resources on digest
calculation.
For such use cases, it is recommended that ZONEMD
only be used when digest calculation time is significantly
less than propagation times and update intervals.
The authors' implementation () includes an option to record and report CPU
usage of its operation. The software was used to generate digests
for more than 800 Top-Level Domain (TLD) zones available from . The table below summarizes the
results for the SIMPLE scheme and SHA384 hash algorithm grouped by
zone size. The Rate column is the mean amount of time per RR to
calculate the digest, running on commodity hardware in early 2020.
Zone Size (RRs)
Rate (msec/RR)
10 - 99
0.00683
100 - 999
0.00551
1000 - 9999
0.00505
10000 - 99999
0.00602
100000 - 999999
0.00845
1000000 - 9999999
0.0108
10000000 - 99999999
0.0148
For example, based on the above table, it takes approximately
0.13 seconds to calculate a SIMPLE SHA384 digest for a zone with
22,000 RRs, and about 2.5 seconds for a zone with 300,000 RRs.
These benchmarks attempt to emulate a worst-case scenario and take
into account the time required to canonicalize the zone for
processing. Each of the 800+ zones were measured three times and
then averaged, with a different random sorting of the input data
prior to each measurement.
Privacy ConsiderationsThis specification has no impact on user privacy.ReferencesNormative ReferencesDomain names - concepts and facilitiesThis RFC is the revised basic definition of The Domain Name System. It obsoletes RFC-882. This memo describes the domain style names and their used for host address look up and electronic mail forwarding. It discusses the clients and servers in the domain name system and the protocol used between them.Domain names - implementation and specificationThis RFC is the revised specification of the protocol and format used in the implementation of the Domain Name System. It obsoletes RFC-883. This memo documents the details of the domain name client - server communication.Key words for use in RFCs to Indicate Requirement LevelsIn many standards track documents several words are used to signify the requirements in the specification. These words are often capitalized. This document defines these words as they should be interpreted in IETF documents. This document specifies an Internet Best Current Practices for the Internet Community, and requests discussion and suggestions for improvements.Resource Records for the DNS Security ExtensionsThis document is part of a family of documents that describe the DNS Security Extensions (DNSSEC). The DNS Security Extensions are a collection of resource records and protocol modifications that provide source authentication for the DNS. 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. This document obsoletes RFC 2535 and incorporates changes from all updates to RFC 2535. [STANDARDS-TRACK]US Secure Hash Algorithms (SHA and SHA-based HMAC and HKDF)Federal Information Processing Standard, FIPSAmbiguity of Uppercase vs Lowercase in RFC 2119 Key WordsRFC 2119 specifies common key words that may be used in protocol specifications. This document aims to reduce the ambiguity by clarifying that only UPPERCASE usage of the key words have the defined special meanings.Informative ReferencesGuidelines for Cryptographic Algorithm Agility and Selecting Mandatory-to-Implement AlgorithmsMany IETF protocols use cryptographic algorithms to provide confidentiality, integrity, authentication, or digital signature. Communicating peers must support a common set of cryptographic algorithms for these mechanisms to work properly. This memo provides guidelines to ensure that protocols have the ability to migrate from one mandatory-to-implement algorithm suite to another over time.Centralized Zone Data ServiceInternet Corporation for Assigned Names and Numbers (ICANN)Background of the Partial Failure of the Name Service for .de DomainsDENICDNS tools for zone signature (file, pkcs11-hsm) and validation, and zone digest (ZONEMD)commit 489de21DNS Zone Transfer-over-TLSNLnet LabsSinodun ITSalesforceSalesforceSalesforce DNS zone transfers are transmitted in clear text, which gives
attackers the opportunity to collect the content of a zone by
eavesdropping on network connections. The DNS Transaction Signature
(TSIG) mechanism is specified to restrict direct zone transfer to
authorized clients only, but it does not add confidentiality. This
document specifies use of TLS, rather then clear text, to prevent
zone content collection via passive monitoring of zone transfers:
XFR-over-TLS (XoT). Additionally, this specification updates
RFC1995, RFC5936 and RFC7766.
Work in ProgressIndex of ftp://rs.internic.net/InterNICImplementation of Message Digests for DNS Zones using the ldns librarycommit 71c0cd1Incremental Zone Transfer in DNSThis document proposes extensions to the DNS protocols to provide an incremental zone transfer (IXFR) mechanism. [STANDARDS-TRACK]Domain Name System Security ExtensionsThe Domain Name System (DNS) has become a critical operational part of the Internet infrastructure yet it has no strong security mechanisms to assure data integrity or authentication. Extensions to the DNS are described that provide these services to security aware resolvers or applications through the use of cryptographic digital signatures. [STANDARDS-TRACK]Dynamic Updates in the Domain Name System (DNS UPDATE)Using this specification of the UPDATE opcode, it is possible to add or delete RRs or RRsets from a specified zone. Prerequisites are specified separately from update operations, and can specify a dependency upon either the previous existence or nonexistence of an RRset, or the existence of a single RR. [STANDARDS-TRACK]Domain Name System Security ExtensionsThis document incorporates feedback on RFC 2065 from early implementers and potential users. [STANDARDS-TRACK]DNS Request and Transaction Signatures ( SIG(0)s )This document describes the minor but non-interoperable changes in Request and Transaction signature resource records ( SIG(0)s ) that implementation experience has deemed necessary. [STANDARDS-TRACK]Distributing Authoritative Name Servers via Shared Unicast AddressesThis memo describes a set of practices intended to enable an authoritative name server operator to provide access to a single named server in multiple locations. The primary motivation for the development and deployment of these practices is to increase the distribution of Domain Name System (DNS) servers to previously under- served areas of the network topology and to reduce the latency for DNS query responses in those areas. This memo provides information for the Internet community.DNS Security Introduction and RequirementsThe Domain Name System Security Extensions (DNSSEC) add data origin authentication and data integrity to the Domain Name System. This document introduces these extensions and describes their capabilities and limitations. This document also discusses the services that the DNS security extensions do and do not provide. Last, this document describes the interrelationships between the documents that collectively describe DNSSEC. [STANDARDS-TRACK]Protocol Modifications for the DNS Security ExtensionsThis document is part of a family of documents that describe the DNS Security Extensions (DNSSEC). The DNS Security Extensions are a collection of new resource records and protocol modifications that add data origin authentication and data integrity to the DNS. This document describes the DNSSEC protocol modifications. This document defines the concept of a signed zone, along with the requirements for serving and resolving by using DNSSEC. These techniques allow a security-aware resolver to authenticate both DNS resource records and authoritative DNS error indications. This document obsoletes RFC 2535 and incorporates changes from all updates to RFC 2535. [STANDARDS-TRACK]OpenPGP Message FormatThis document is maintained in order to publish all necessary information needed to develop interoperable applications based on the OpenPGP format. It is not a step-by-step cookbook for writing an application. It describes only the format and methods needed to read, check, generate, and write conforming packets crossing any network. It does not deal with storage and implementation questions. It does, however, discuss implementation issues necessary to avoid security flaws.OpenPGP software uses a combination of strong public-key and symmetric cryptography to provide security services for electronic communications and data storage. These services include confidentiality, key management, authentication, and digital signatures. This document specifies the message formats used in OpenPGP. [STANDARDS-TRACK]DNS Security (DNSSEC) Hashed Authenticated Denial of ExistenceThe Domain Name System Security (DNSSEC) Extensions introduced the NSEC resource record (RR) for authenticated denial of existence. This document introduces an alternative resource record, NSEC3, which similarly provides authenticated denial of existence. However, it also provides measures against zone enumeration and permits gradual expansion of delegation-centric zones. [STANDARDS-TRACK]DNS Zone Transfer Protocol (AXFR)The standard means within the Domain Name System protocol for maintaining coherence among a zone's authoritative name servers consists of three mechanisms. Authoritative Transfer (AXFR) is one of the mechanisms and is defined in RFC 1034 and RFC 1035.The definition of AXFR has proven insufficient in detail, thereby forcing implementations intended to be compliant to make assumptions, impeding interoperability. Yet today we have a satisfactory set of implementations that do interoperate. This document is a new definition of AXFR -- new in the sense that it records an accurate definition of an interoperable AXFR mechanism. [STANDARDS-TRACK]Guidelines for Writing an IANA Considerations Section in RFCsMany protocols make use of points of extensibility that use constants to identify various protocol parameters. To ensure that the values in these fields do not have conflicting uses and to promote interoperability, their allocations are often coordinated by a central record keeper. For IETF protocols, that role is filled by the Internet Assigned Numbers Authority (IANA).To make assignments in a given registry prudently, guidance describing the conditions under which new values should be assigned, as well as when and how modifications to existing values can be made, is needed. This document defines a framework for the documentation of these guidelines by specification authors, in order to assure that the provided guidance for the IANA Considerations is clear and addresses the various issues that are likely in the operation of a registry.This is the third edition of this document; it obsoletes RFC 5226.DNS Queries over HTTPS (DoH)This document defines a protocol for sending DNS queries and getting DNS responses over HTTPS. Each DNS query-response pair is mapped into an HTTP exchange.DNS TerminologyThe Domain Name System (DNS) is defined in literally dozens of different RFCs. The terminology used by implementers and developers of DNS protocols, and by operators of DNS systems, has sometimes changed in the decades since the DNS was first defined. This document gives current definitions for many of the terms used in the DNS in a single document.This document obsoletes RFC 7719 and updates RFC 2308.Secure/Multipurpose Internet Mail Extensions (S/MIME) Version 4.0 Message SpecificationThis document defines Secure/Multipurpose Internet Mail Extensions (S/MIME) version 4.0. S/MIME provides a consistent way to send and receive secure MIME data. Digital signatures provide authentication, message integrity, and non-repudiation with proof of origin. Encryption provides data confidentiality. Compression can be used to reduce data size. This document obsoletes RFC 5751.Running a Root Server Local to a ResolverSome DNS recursive resolvers have longer-than-desired round-trip times to the closest DNS root server; those resolvers may have difficulty getting responses from the root servers, such as during a network attack. Some DNS recursive resolver operators want to prevent snooping by third parties of requests sent to DNS root servers. In both cases, resolvers can greatly decrease the round-trip time and prevent observation of requests by serving a copy of the full root zone on the same server, such as on a loopback address or in the resolver software. This document shows how to start and maintain such a copy of the root zone that does not cause problems for other users of the DNS, at the cost of adding some operational fragility for the operator.This document obsoletes RFC 7706.Multi-Signer DNSSEC ModelsMany enterprises today employ the service of multiple DNS providers to distribute their authoritative DNS service. Deploying DNSSEC in such an environment may present some challenges, depending on the configuration and feature set in use. In particular, when each DNS provider independently signs zone data with their own keys, additional key-management mechanisms are necessary. This document presents deployment models that accommodate this scenario and describes these key-management requirements. These models do not require any changes to the behavior of validating resolvers, nor do they impose the new key-management requirements on authoritative servers not involved in multi-signer configurations.Secret Key Transaction Authentication for DNS (TSIG)This document describes a protocol for transaction-level authentication using shared secrets and one-way hashing. It can be used to authenticate dynamic updates to a DNS zone as coming from an approved client or to authenticate responses as coming from an approved name server.No recommendation is made here for distributing the shared secrets; it is expected that a network administrator will statically configure name servers and clients using some out-of-band mechanism.This document obsoletes RFCs 2845 and 4635.root-servers.orgRoot Server OperatorsResponse policy zoneWikipediaPrototype implementation of ZONEMD for the IETF 102 hackathoncommit 76ad7a7RFC 8976 ZONEMD Test CasesIETFExample Zones with Digests
This appendix contains example zones with accurate ZONEMD records.
These can be used to verify an implementation of the zone digest
protocol. Additional and more extensive test cases can be found via
the ZONEMD Tests Wiki () maintained by
the IETF DNSOP Working Group.
Simple EXAMPLE Zone
Here, the EXAMPLE zone contains an SOA record, NS and glue records, and a ZONEMD record.
example. 86400 IN SOA ns1 admin 2018031900 (
1800 900 604800 86400 )
86400 IN NS ns1
86400 IN NS ns2
86400 IN ZONEMD 2018031900 1 1 (
c68090d90a7aed71
6bc459f9340e3d7c
1370d4d24b7e2fc3
a1ddc0b9a87153b9
a9713b3c9ae5cc27
777f98b8e730044c )
ns1 3600 IN A 203.0.113.63
ns2 3600 IN AAAA 2001:db8::63
Complex EXAMPLE Zone
Here, the EXAMPLE zone contains duplicate RRs, an occluded RR, uppercase names, a wildcard, a multi-record RRset, a non-apex ZONEMD RR, and one out-of-zone RR.
example. 86400 IN SOA ns1 admin 2018031900 (
1800 900 604800 86400 )
86400 IN NS ns1
86400 IN NS ns2
86400 IN ZONEMD 2018031900 1 1 (
a3b69bad980a3504
e1cffcb0fd6397f9
3848071c93151f55
2ae2f6b1711d4bd2
d8b39808226d7b9d
b71e34b72077f8fe )
ns1 3600 IN A 203.0.113.63
NS2 3600 IN AAAA 2001:db8::63
occluded.sub 7200 IN TXT "I'm occluded but must be digested"
sub 7200 IN NS ns1
duplicate 300 IN TXT "I must be digested just once"
duplicate 300 IN TXT "I must be digested just once"
foo.test. 555 IN TXT "out-of-zone data must be excluded"
UPPERCASE 3600 IN TXT "canonicalize uppercase owner names"
* 777 IN PTR dont-forget-about-wildcards
mail 3600 IN MX 20 MAIL1
mail 3600 IN MX 10 Mail2.Example.
sortme 3600 IN AAAA 2001:db8::5:61
sortme 3600 IN AAAA 2001:db8::3:62
sortme 3600 IN AAAA 2001:db8::4:63
sortme 3600 IN AAAA 2001:db8::1:65
sortme 3600 IN AAAA 2001:db8::2:64
non-apex 900 IN ZONEMD 2018031900 1 1 (
616c6c6f77656420
6275742069676e6f
7265642e20616c6c
6f77656420627574
2069676e6f726564
2e20616c6c6f7765 )
EXAMPLE Zone with Multiple Digests
Here, the EXAMPLE zone contains multiple ZONEMD records. It has both
SHA384 and SHA512 digests using the SIMPLE scheme. It also includes
ZONEMD records with Scheme and Hash Algorithm
values in the private range (240-254). These additional
private-range digests are not verifiable.
example. 86400 IN SOA ns1 admin 2018031900 (
1800 900 604800 86400 )
example. 86400 IN NS ns1.example.
example. 86400 IN NS ns2.example.
example. 86400 IN ZONEMD 2018031900 1 1 (
62e6cf51b02e54b9
b5f967d547ce4313
6792901f9f88e637
493daaf401c92c27
9dd10f0edb1c56f8
080211f8480ee306 )
example. 86400 IN ZONEMD 2018031900 1 2 (
08cfa1115c7b948c
4163a901270395ea
226a930cd2cbcf2f
a9a5e6eb85f37c8a
4e114d884e66f176
eab121cb02db7d65
2e0cc4827e7a3204
f166b47e5613fd27 )
example. 86400 IN ZONEMD 2018031900 1 240 (
e2d523f654b9422a
96c5a8f44607bbee )
example. 86400 IN ZONEMD 2018031900 241 1 (
e1846540e33a9e41
89792d18d5d131f6
05fc283e )
ns1.example. 3600 IN A 203.0.113.63
ns2.example. 86400 IN TXT "This example has multiple digests"
NS2.EXAMPLE. 3600 IN AAAA 2001:db8::63
The URI.ARPA Zone
The following sample zone is the URI.ARPA zone retrieved 2021-01-21. Note this sample zone has
been re-signed with unpublished keys, so that the added ZONEMD RR also has a signature.
uri.arpa. 3600 IN SOA sns.dns.icann.org. (
noc.dns.icann.org. 2018100702 10800 3600 1209600 3600 )
uri.arpa. 3600 IN RRSIG SOA 8 2 3600 (
20210217232440 20210120232440 37444 uri.arpa.
GzQw+QzwLDJr13REPGVmpEChjD1D2XlX0ie1DnWHpgaEw1E/dhs3lCN3+B
mHd4Kx3tffTRgiyq65HxR6feQ5v7VmAifjyXUYB1DZur1eP5q0Ms2ygCB3
byoeMgCNsFS1oKZ2LdzNBRpy3oace8xQn1SpmHGfyrsgg+WbHKCT1dY= )
uri.arpa. 86400 IN NS a.iana-servers.net.
uri.arpa. 86400 IN NS b.iana-servers.net.
uri.arpa. 86400 IN NS c.iana-servers.net.
uri.arpa. 86400 IN NS ns2.lacnic.net.
uri.arpa. 86400 IN NS sec3.apnic.net.
uri.arpa. 86400 IN RRSIG NS 8 2 86400 (
20210217232440 20210120232440 37444 uri.arpa.
M+Iei2lcewWGaMtkPlrhM9FpUAHXFkCHTVpeyrjxjEONeNgKtHZor5e4V4
qJBOzNqo8go/qJpWlFBm+T5Hn3asaBZVstFIYky38/C8UeRLPKq1hTTHAR
YUlFrexr5fMtSUAVOgOQPSBfH3xBq/BgSccTdRb9clD+HE7djpqrLS4= )
uri.arpa. 600 IN MX 10 pechora.icann.org.
uri.arpa. 600 IN RRSIG MX 8 2 600 (
20210217232440 20210120232440 37444 uri.arpa.
kQAJQivmv6A5hqYBK8h6Z13ESY69gmosXwKI6WE09I8RFetfrxr24ecdnY
d0lpnDtgNNSoHkYRSOoB+C4+zuJsoyAAzGo9uoWMWj97/2xeGhf3PTC9me
Q9Ohi6hul9By7OR76XYmGhdWX8PBi60RUmZ1guslFBfQ8izwPqzuphs= )
uri.arpa. 3600 IN DNSKEY 256 3 8 (
AwEAAbMxuFuLeVDuOwIMzYOTD/bTREjLflo7wOi6ieIJhqltEzgjNzmWJf
9kGwwDmzxU7kbthMEhBNBZNn84zmcyRSCMzuStWveL7xmqqUlE3swL8kLO
vdZvc75XnmpHrk3ndTyEb6eZM7slh2C63Oh6K8VR5VkiZAkEGg0uZIT3Nj
sF )
uri.arpa. 3600 IN DNSKEY 257 3 8 (
AwEAAdkTaWkZtZuRh7/OobBUFxM+ytTst+bCu0r9w+rEwXD7GbDs0pIMhM
enrZzoAvmv1fQxw2MGs6Ri6yPKfNULcFOSt9l8i6BVBLI+SKTY6XXeDUQp
SEmSaxohHeRPMQFzpysfjxINp/L2rGtZ7yPmxY/XRiFPSO0myqwGJa9r06
Zw9CHM5UDHKWV/E+zxPFq/I7CfPbrrzbUotBX7Z6Vh3Sarllbe8cGUB2UF
NaTRgwB0TwDBPRD5ER3w2Dzbry9NhbElTr7vVfhaGWeOGuqAUXwlXEg6Cr
NkmJXJ2F1Rzr9WHUzhp7uWxhAbmJREGfi2dEyPAbUAyCjBqhFaqglknvc= )
uri.arpa. 3600 IN DNSKEY 257 3 8 (
AwEAAenQaBoFmDmvRT+/H5oNbm0Tr5FmNRNDEun0Jpj/ELkzeUrTWhNpQm
ZeIMC8I0kZ185tEvOnRvn8OvV39B17QIdrvvKGIh2HlgeDRCLolhaojfn2
QM0DStjF/WWHpxJOmE6CIuvhqYEU37yoJscGAPpPVPzNvnL1HhYTaao1VR
YWQ/maMrJ+bfHg+YX1N6M/8MnRjIKBif1FWjbCKvsn6dnuGGL9oCWYUFJ3
DwofXuhgPyZMkzPc88YkJj5EMvbMH4wtelbCwC+ivx732l0w/rXJn0ciQS
OgoeVvDio8dIJmWQITWQAuP+q/ZHFEFHPlrP3gvQh5mcVS48eLX71Bq7c= )
uri.arpa. 3600 IN RRSIG DNSKEY 8 2 3600 (
20210217232440 20210120232440 12670 uri.arpa.
DBE2gkKAoxJCfz47KKxzoImN/0AKArhIVHE7TyTwy0DdRPo44V5R+vL6th
UxlQ1CJi2Rw0jwAXymx5Y3Q873pOEllH+4bJoIT4dmoBmPXfYWW7Clvw9U
PKHRP0igKHmCVwIeBYDTU3gfLcMTbR4nEWPDN0GxlL1Mf7ITaC2Ioabo79
Ip3M/MR8I3Vx/xZ4ZKKPHtLn3xUuJluPNanqJrED2gTslL2xWZ1tqjsAjJ
v7JnJo2HJ8XVRB5zBto0IaJ2oBlqcjdcQ/0VlyoM8uOy1pDwHQ2BJl7322
gNMHBP9HSiUPIOaIDNUCwW8eUcW6DIUk+s9u3GN1uTqwWzsYB/rA== )
uri.arpa. 3600 IN RRSIG DNSKEY 8 2 3600 (
20210217232440 20210120232440 30577 uri.arpa.
Kx6HwP4UlkGc1UZ7SERXtQjPajOF4iUvkwDj7MEG1xbQFB1KoJiEb/eiW0
qmSWdIhMDv8myhgauejRLyJxwxz8HDRV4xOeHWnRGfWBk4XGYwkejVzOHz
oIArVdUVRbr2JKigcTOoyFN+uu52cNB7hRYu7dH5y1hlc6UbOnzRpMtGxc
gVyKQ+/ARbIqGG3pegdEOvV49wTPWEiyY65P2urqhvnRg5ok/jzwAdMx4X
Gshiib7Ojq0sRVl2ZIzj4rFgY/qsSO8SEXEhMo2VuSkoJNiofVzYoqpxEe
GnANkIT7Tx2xJL1BWyJxyc7E8Wr2QSgCcc+rYL6IkHDtJGHy7TaQ== )
uri.arpa. 3600 IN ZONEMD 2018100702 1 1 (
0dbc3c4dbfd75777c12ca19c337854b1577799901307c482e9d91d5d15
cd934d16319d98e30c4201cf25a1d5a0254960 )
uri.arpa. 3600 IN RRSIG ZONEMD 8 2 3600 (
20210217232440 20210120232440 37444 uri.arpa.
QDo4XZcL3HMyn8aAHyCUsu/Tqj4Gkth8xY1EqByOb8XOTwVtA4ZNQORE1s
iqNqjtJUbeJPtJSbLNqCL7rCq0CzNNnBscv6IIf4gnqJZjlGtHO30ohXtK
vEc4z7SU3IASsi6bB3nLmEAyERdYSeU6UBfx8vatQDIRhkgEnnWUTh4= )
uri.arpa. 3600 IN NSEC ftp.uri.arpa. (
NS SOA MX RRSIG NSEC DNSKEY ZONEMD )
uri.arpa. 3600 IN RRSIG NSEC 8 2 3600 (
20210217232440 20210120232440 37444 uri.arpa.
dU/rXLM/naWd1+1PiWiYVaNJyCkiuyZJSccr91pJI673T8r3685B4ODMYF
afZRboVgwnl3ZrXddY6xOhZL3n9V9nxXZwjLJ2HJUojFoKcXTlpnUyYUYv
VQ2kj4GHAo6fcGCEp5QFJ2KbCpeJoS+PhKGRRx28icCiNT4/uXQvO2E= )
ftp.uri.arpa. 604800 IN NAPTR 0 0 "" "" (
"!^ftp://([^:/?#]*).*$!\\1!i" . )
ftp.uri.arpa. 604800 IN RRSIG NAPTR 8 3 604800 (
20210217232440 20210120232440 37444 uri.arpa.
EygekDgl+Lyyq4NMSEpPyOrOywYf9Y3FAB4v1DT44J3R5QGidaH8l7ZFjH
oYFI8sY64iYOCV4sBnX/dh6C1L5NgpY+8l5065Xu3vvjyzbtuJ2k6YYwJr
rCbvl5DDn53zAhhO2hL9uLgyLraZGi9i7TFGd0sm3zNyUF/EVL0CcxU= )
ftp.uri.arpa. 3600 IN NSEC http.uri.arpa. (
NAPTR RRSIG NSEC )
ftp.uri.arpa. 3600 IN RRSIG NSEC 8 3 3600 (
20210217232440 20210120232440 37444 uri.arpa.
pbP4KxevPXCu/bDqcvXiuBppXyFEmtHyiy0eAN5gS7mi6mp9Z9bWFjx/Ld
H9+6oFGYa5vGmJ5itu/4EDMe8iQeZbI8yrpM4TquB7RR/MGfBnTd8S+sjy
QtlRYG7yqEu77Vd78Fme22BKPJ+MVqjS0JHMUE/YUGomPkAjLJJwwGw= )
http.uri.arpa. 604800 IN NAPTR 0 0 "" "" (
"!^http://([^:/?#]*).*$!\\1!i" . )
http.uri.arpa. 604800 IN RRSIG NAPTR 8 3 604800 (
20210217232440 20210120232440 37444 uri.arpa.
eTqbWvt1GvTeXozuvm4ebaAfkXFQKrtdu0cEiExto80sHIiCbO0WL8UDa/
J3cDivtQca7LgUbOb6c17NESsrsVkc6zNPx5RK2tG7ZQYmhYmtqtfg1oU5
BRdHZ5TyqIXcHlw9Blo2pir1Y9IQgshhD7UOGkbkEmvB1Lrd0aHhAAg= )
http.uri.arpa. 3600 IN NSEC mailto.uri.arpa. (
NAPTR RRSIG NSEC )
http.uri.arpa. 3600 IN RRSIG NSEC 8 3 3600 (
20210217232440 20210120232440 37444 uri.arpa.
R9rlNzw1CVz2N08q6DhULzcsuUm0UKcPaGAWEU40tr81jEDHsFHNM+khCd
OI8nDstzA42aee4rwCEgijxJpRCcY9hrO1Ysrrr2fdqNz60JikMdarvU5O
0p0VXeaaJDfJQT44+o+YXaBwI7Qod3FTMx7aRib8i7istvPm1Rr7ixA= )
mailto.uri.arpa. 604800 IN NAPTR 0 0 "" "" (
"!^mailto:(.*)@(.*)$!\\2!i" . )
mailto.uri.arpa. 604800 IN RRSIG NAPTR 8 3 604800 (
20210217232440 20210120232440 37444 uri.arpa.
Ch2zTG2F1plEvQPyIH4Yd80XXLjXOPvMbiqDjpJBcnCJsV8QF7kr0wTLnU
T3dB+asQudOjPyzaHGwFlMzmrrAsszN4XAMJ6htDtFJdsgTMP/NkHhYRSm
Vv6rLeAhd+mVfObY12M//b/GGVTjeUI/gJaLW0fLVZxr1Fp5U5CRjyw= )
mailto.uri.arpa. 3600 IN NSEC urn.uri.arpa. (
NAPTR RRSIG NSEC )
mailto.uri.arpa. 3600 IN RRSIG NSEC 8 3 3600 (
20210217232440 20210120232440 37444 uri.arpa.
fQUbSIE6E7JDi2rosah4SpCOTrKufeszFyj5YEavbQuYlQ5cNFvtm8KuE2
xXMRgRI4RGvM2leVqcoDw5hS3m2pOJLxH8l2WE72YjYvWhvnwc5Rofe/8y
B/vaSK9WCnqN8y2q6Vmy73AGP0fuiwmuBra7LlkOiqmyx3amSFizwms= )
urn.uri.arpa. 604800 IN NAPTR 0 0 "" "" (
"/urn:([^:]+)/\\1/i" . )
urn.uri.arpa. 604800 IN RRSIG NAPTR 8 3 604800 (
20210217232440 20210120232440 37444 uri.arpa.
CVt2Tgz0e5ZmaSXqRfNys/8OtVCk9nfP0zhezhN8Bo6MDt6yyKZ2kEEWJP
jkN7PCYHjO8fGjnUn0AHZI2qBNv7PKHcpR42VY03q927q85a65weOO1YE0
vPYMzACpua9TOtfNnynM2Ws0uN9URxUyvYkXBdqOC81N3sx1dVELcwc= )
urn.uri.arpa. 3600 IN NSEC uri.arpa. NAPTR RRSIG NSEC
urn.uri.arpa. 3600 IN RRSIG NSEC 8 3 3600 (
20210217232440 20210120232440 37444 uri.arpa.
JuKkMiC3/j9iM3V8/izcouXWAVGnSZjkOgEgFPhutMqoylQNRcSkbEZQzF
K8B/PIVdzZF0Y5xkO6zaKQjOzz6OkSaNPIo1a7Vyyl3wDY/uLCRRAHRJfp
knuY7O+AUNXvVVIEYJqZggd4kl/Rjh1GTzPYZTRrVi5eQidI1LqCOeg= )
The ROOT-SERVERS.NET Zone
The following sample zone is the ROOT-SERVERS.NET zone retrieved 2018-10-21.
root-servers.net. 3600000 IN SOA a.root-servers.net. (
nstld.verisign-grs.com. 2018091100 14400 7200 1209600 3600000 )
root-servers.net. 3600000 IN NS a.root-servers.net.
root-servers.net. 3600000 IN NS b.root-servers.net.
root-servers.net. 3600000 IN NS c.root-servers.net.
root-servers.net. 3600000 IN NS d.root-servers.net.
root-servers.net. 3600000 IN NS e.root-servers.net.
root-servers.net. 3600000 IN NS f.root-servers.net.
root-servers.net. 3600000 IN NS g.root-servers.net.
root-servers.net. 3600000 IN NS h.root-servers.net.
root-servers.net. 3600000 IN NS i.root-servers.net.
root-servers.net. 3600000 IN NS j.root-servers.net.
root-servers.net. 3600000 IN NS k.root-servers.net.
root-servers.net. 3600000 IN NS l.root-servers.net.
root-servers.net. 3600000 IN NS m.root-servers.net.
a.root-servers.net. 3600000 IN AAAA 2001:503:ba3e::2:30
a.root-servers.net. 3600000 IN A 198.41.0.4
b.root-servers.net. 3600000 IN MX 20 mail.isi.edu.
b.root-servers.net. 3600000 IN AAAA 2001:500:200::b
b.root-servers.net. 3600000 IN A 199.9.14.201
c.root-servers.net. 3600000 IN AAAA 2001:500:2::c
c.root-servers.net. 3600000 IN A 192.33.4.12
d.root-servers.net. 3600000 IN AAAA 2001:500:2d::d
d.root-servers.net. 3600000 IN A 199.7.91.13
e.root-servers.net. 3600000 IN AAAA 2001:500:a8::e
e.root-servers.net. 3600000 IN A 192.203.230.10
f.root-servers.net. 3600000 IN AAAA 2001:500:2f::f
f.root-servers.net. 3600000 IN A 192.5.5.241
g.root-servers.net. 3600000 IN AAAA 2001:500:12::d0d
g.root-servers.net. 3600000 IN A 192.112.36.4
h.root-servers.net. 3600000 IN AAAA 2001:500:1::53
h.root-servers.net. 3600000 IN A 198.97.190.53
i.root-servers.net. 3600000 IN MX 10 mx.i.root-servers.org.
i.root-servers.net. 3600000 IN AAAA 2001:7fe::53
i.root-servers.net. 3600000 IN A 192.36.148.17
j.root-servers.net. 3600000 IN AAAA 2001:503:c27::2:30
j.root-servers.net. 3600000 IN A 192.58.128.30
k.root-servers.net. 3600000 IN AAAA 2001:7fd::1
k.root-servers.net. 3600000 IN A 193.0.14.129
l.root-servers.net. 3600000 IN AAAA 2001:500:9f::42
l.root-servers.net. 3600000 IN A 199.7.83.42
m.root-servers.net. 3600000 IN AAAA 2001:dc3::35
m.root-servers.net. 3600000 IN A 202.12.27.33
root-servers.net. 3600000 IN SOA a.root-servers.net. (
nstld.verisign-grs.com. 2018091100 14400 7200 1209600 3600000 )
root-servers.net. 3600000 IN ZONEMD 2018091100 1 1 (
f1ca0ccd91bd5573d9f431c00ee0101b2545c97602be0a97
8a3b11dbfc1c776d5b3e86ae3d973d6b5349ba7f04340f79 )
Implementation Status
This section records the status of known implementations of the
protocol defined by this specification at the time of publication, and is inspired by the
concepts described in RFC 7942.
Please note that the listing of any
individual implementation here does not imply endorsement by the
IETF. Furthermore, no effort has been spent to verify the
information presented here that was supplied by IETF contributors.
This is not intended as, and must not be construed to be, a
catalog of available implementations or their features. Readers
are advised to note that other implementations may exist.
Authors' Implementation
The authors have an open-source implementation in C, using the ldns
library (). This
implementation is able to perform the following functions:
Read an input zone and output a zone with the ZONEMD placeholder.
Compute the zone digest over the signed zone and update the ZONEMD
record.
Recompute DNSSEC signatures over the ZONEMD record.
Verify the zone digest from an input zone.
This implementation does not:
Perform DNSSEC validation of the ZONEMD record during verification.
Shane Kerr's Implementation wrote an implementation of this
specification during the IETF 102 hackathon (). This implementation
is in Python and is able to perform the following functions:
Read an input zone and output a zone with ZONEMD record.
Verify the zone digest from an input zone.
Output the ZONEMD record in its defined presentation format.
This implementation does not:
Recompute DNSSEC signatures over the ZONEMD record.
Perform DNSSEC validation of the ZONEMD record.
NIC Chile Lab's Implementation
NIC Chile Labs wrote an implementation of this specification
as part of "dns-tools" suite (),
which besides digesting, can also sign and verify zones. This
implementation is in Go and is able to perform the following
functions:
Compute zone digest over signed zone and update the ZONEMD record.
Verify the zone digest from an input zone.
Perform DNSSEC validation of the ZONEMD record during verification.
Recompute DNSSEC signatures over the ZONEMD record.
Acknowledgments
The authors wish to thank , , and
for providing feedback on early drafts of this document.
Additionally, they thank , , ,
, , , , , , , , ,
, ,
, ,
, ,
, , , , ,
, , , , and other members of the DNSOP Working
Group for their input.
The authors would again like to thank , who served as the Document
Shepherd for this document.
Authors' AddressesVerisign12061 Bluemont WayRestonVA20190United States of America+1 703 948-3200dwessels@verisign.comhttps://verisign.comVerisign12061 Bluemont WayRestonVA20190United States of America+1 703 948-3200pbarber@verisign.comhttps://verisign.comAmazonmatweinb@amazon.comhttps://amazon.comGoogle1600 Amphitheatre ParkwayMountain ViewCA94043United States of Americawarren@kumari.netUSC/ISIP.O. Box 382DavisCA95617United States of Americaietf@hardakers.net