< draft-ietf-dnsop-dns-zone-digest-12.txt   draft-ietf-dnsop-dns-zone-digest-13.txt >
Internet Engineering Task Force D. Wessels Internet Engineering Task Force D. Wessels
Internet-Draft P. Barber Internet-Draft P. Barber
Intended status: Standards Track Verisign Intended status: Standards Track Verisign
Expires: April 2, 2021 M. Weinberg Expires: April 12, 2021 M. Weinberg
Amazon Amazon
W. Kumari W. Kumari
Google Google
W. Hardaker W. Hardaker
USC/ISI USC/ISI
September 29, 2020 October 9, 2020
Message Digest for DNS Zones Message Digest for DNS Zones
draft-ietf-dnsop-dns-zone-digest-12 draft-ietf-dnsop-dns-zone-digest-13
Abstract Abstract
This document describes a protocol and new DNS Resource Record that This document describes a protocol and new DNS Resource Record that
provides a cryptographic message digest over DNS zone data. The provides a cryptographic message digest over DNS zone data at rest.
ZONEMD Resource Record conveys the digest data in the zone itself. The ZONEMD Resource Record conveys the digest data in the zone
When a zone publisher includes a ZONEMD record, recipients can verify itself. When used in combination with DNSSEC, ZONEMD allows
the zone contents for accuracy and completeness. This provides recipients to verify the zone contents for data integrity and origin
assurance that received zone data matches published data, regardless authenticity. This provides assurance that received zone data
of how the zone data has been transmitted and received. 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. Whereas DNSSEC protects individual ZONEMD does not replace DNSSEC. Whereas DNSSEC protects individual
RRSets (DNS data with fine granularity), ZONEMD protects a zone's RRSets (DNS data with fine granularity), ZONEMD protects a zone's
data as a whole, whether consumed by authoritative name servers, data as a whole, whether consumed by authoritative name servers,
recursive name servers, or any other applications. recursive name servers, or any other applications.
As specified herein, ZONEMD is impractical for large, dynamic zones As specified herein, ZONEMD is impractical for large, dynamic zones
due to the time and resources required for digest calculation. due to the time and resources required for digest calculation.
However, The ZONEMD record is extensible so that new digest schemes However, The ZONEMD record is extensible so that new digest schemes
may be added in the future to support large, dynamic zones. may be added in the future to support large, dynamic zones.
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Internet-Drafts are working documents of the Internet Engineering Internet-Drafts are working documents of the Internet Engineering
Task Force (IETF). Note that other groups may also distribute Task Force (IETF). Note that other groups may also distribute
working documents as Internet-Drafts. The list of current Internet- working documents as Internet-Drafts. The list of current Internet-
Drafts is at https://datatracker.ietf.org/drafts/current/. Drafts is at https://datatracker.ietf.org/drafts/current/.
Internet-Drafts are draft documents valid for a maximum of six months Internet-Drafts are draft documents valid for a maximum of six months
and may be updated, replaced, or obsoleted by other documents at any and may be updated, replaced, or obsoleted by other documents at any
time. It is inappropriate to use Internet-Drafts as reference time. It is inappropriate to use Internet-Drafts as reference
material or to cite them other than as "work in progress." material or to cite them other than as "work in progress."
This Internet-Draft will expire on April 2, 2021. This Internet-Draft will expire on April 12, 2021.
Copyright Notice Copyright Notice
Copyright (c) 2020 IETF Trust and the persons identified as the Copyright (c) 2020 IETF Trust and the persons identified as the
document authors. All rights reserved. document authors. All rights reserved.
This document is subject to BCP 78 and the IETF Trust's Legal This document is subject to BCP 78 and the IETF Trust's Legal
Provisions Relating to IETF Documents Provisions Relating to IETF Documents
(https://trustee.ietf.org/license-info) in effect on the date of (https://trustee.ietf.org/license-info) in effect on the date of
publication of this document. Please review these documents publication of this document. Please review these documents
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described in the Simplified BSD License. described in the Simplified BSD License.
Table of Contents Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3
1.1. Motivation . . . . . . . . . . . . . . . . . . . . . . . 4 1.1. Motivation . . . . . . . . . . . . . . . . . . . . . . . 4
1.2. Alternative Approaches . . . . . . . . . . . . . . . . . 4 1.2. Alternative Approaches . . . . . . . . . . . . . . . . . 4
1.3. Design Overview . . . . . . . . . . . . . . . . . . . . . 6 1.3. Design Overview . . . . . . . . . . . . . . . . . . . . . 6
1.4. Use Cases . . . . . . . . . . . . . . . . . . . . . . . . 6 1.4. Use Cases . . . . . . . . . . . . . . . . . . . . . . . . 6
1.4.1. Root Zone . . . . . . . . . . . . . . . . . . . . . . 6 1.4.1. Root Zone . . . . . . . . . . . . . . . . . . . . . . 6
1.4.2. Providers, Secondaries, and Anycast . . . . . . . . . 6 1.4.2. Providers, Secondaries, and Anycast . . . . . . . . . 7
1.4.3. Response Policy Zones . . . . . . . . . . . . . . . . 7 1.4.3. Response Policy Zones . . . . . . . . . . . . . . . . 7
1.4.4. Centralized Zone Data Service . . . . . . . . . . . . 7 1.4.4. Centralized Zone Data Service . . . . . . . . . . . . 7
1.4.5. General Purpose Comparison Check . . . . . . . . . . 7 1.4.5. General Purpose Comparison Check . . . . . . . . . . 7
1.5. Terminology . . . . . . . . . . . . . . . . . . . . . . . 7 1.5. Terminology . . . . . . . . . . . . . . . . . . . . . . . 8
2. The ZONEMD Resource Record . . . . . . . . . . . . . . . . . 7 2. The ZONEMD Resource Record . . . . . . . . . . . . . . . . . 8
2.1. Non-apex ZONEMD Records . . . . . . . . . . . . . . . . . 8 2.1. Non-apex ZONEMD Records . . . . . . . . . . . . . . . . . 8
2.2. ZONEMD RDATA Wire Format . . . . . . . . . . . . . . . . 8 2.2. ZONEMD RDATA Wire Format . . . . . . . . . . . . . . . . 8
2.2.1. The Serial Field . . . . . . . . . . . . . . . . . . 8 2.2.1. The Serial Field . . . . . . . . . . . . . . . . . . 9
2.2.2. The Scheme Field . . . . . . . . . . . . . . . . . . 9 2.2.2. The Scheme Field . . . . . . . . . . . . . . . . . . 9
2.2.3. The Hash Algorithm Field . . . . . . . . . . . . . . 9 2.2.3. The Hash Algorithm Field . . . . . . . . . . . . . . 9
2.2.4. The Digest Field . . . . . . . . . . . . . . . . . . 9 2.2.4. The Digest Field . . . . . . . . . . . . . . . . . . 10
2.3. ZONEMD Presentation Format . . . . . . . . . . . . . . . 10 2.3. ZONEMD Presentation Format . . . . . . . . . . . . . . . 10
2.4. ZONEMD Example . . . . . . . . . . . . . . . . . . . . . 10 2.4. ZONEMD Example . . . . . . . . . . . . . . . . . . . . . 10
3. Calculating the Digest . . . . . . . . . . . . . . . . . . . 10 3. Calculating the Digest . . . . . . . . . . . . . . . . . . . 11
3.1. Add ZONEMD Placeholder . . . . . . . . . . . . . . . . . 10 3.1. Add ZONEMD Placeholder . . . . . . . . . . . . . . . . . 11
3.2. Optionally Sign the Zone . . . . . . . . . . . . . . . . 11 3.2. Optionally Sign the Zone . . . . . . . . . . . . . . . . 11
3.3. Scheme-Specific Processing . . . . . . . . . . . . . . . 11 3.3. Scheme-Specific Processing . . . . . . . . . . . . . . . 12
3.3.1. The SIMPLE Scheme . . . . . . . . . . . . . . . . . . 11 3.3.1. The SIMPLE Scheme . . . . . . . . . . . . . . . . . . 12
3.3.1.1. SIMPLE Scheme Inclusion/Exclusion Rules . . . . . 11 3.3.1.1. SIMPLE Scheme Inclusion/Exclusion Rules . . . . . 12
3.3.1.2. SIMPLE Scheme Digest Calculation . . . . . . . . 12 3.3.1.2. SIMPLE Scheme Digest Calculation . . . . . . . . 12
3.4. Update ZONEMD RR . . . . . . . . . . . . . . . . . . . . 12 3.4. Update ZONEMD RR . . . . . . . . . . . . . . . . . . . . 13
4. Verifying Zone Digest . . . . . . . . . . . . . . . . . . . . 12 4. Verifying Zone Digest . . . . . . . . . . . . . . . . . . . . 13
5. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 14 5. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 15
5.1. ZONEMD RRtype . . . . . . . . . . . . . . . . . . . . . . 14 5.1. ZONEMD RRtype . . . . . . . . . . . . . . . . . . . . . . 15
5.2. ZONEMD Scheme . . . . . . . . . . . . . . . . . . . . . . 14 5.2. ZONEMD Scheme . . . . . . . . . . . . . . . . . . . . . . 15
5.3. ZONEMD Hash Algorithm . . . . . . . . . . . . . . . . . . 15 5.3. ZONEMD Hash Algorithm . . . . . . . . . . . . . . . . . . 15
6. Security Considerations . . . . . . . . . . . . . . . . . . . 15 6. Security Considerations . . . . . . . . . . . . . . . . . . . 16
6.1. Attacks Against the Zone Digest . . . . . . . . . . . . . 16 6.1. Using Zone Digest Without DNSSEC . . . . . . . . . . . . 16
6.2. DNSSESC Timing Considerations . . . . . . . . . . . . . . 16 6.2. Attacks Against the Zone Digest . . . . . . . . . . . . . 16
6.3. Attacks Utilizing ZONEMD Queries . . . . . . . . . . . . 16 6.3. Use of Multiple ZONEMD Hash Algorithms . . . . . . . . . 17
6.4. Resilience and Fragility . . . . . . . . . . . . . . . . 17 6.4. DNSSEC Timing Considerations . . . . . . . . . . . . . . 17
7. Performance Considerations . . . . . . . . . . . . . . . . . 17 6.5. Attacks Utilizing ZONEMD Queries . . . . . . . . . . . . 17
7.1. SIMPLE SHA384 . . . . . . . . . . . . . . . . . . . . . . 17 6.6. Resilience and Fragility . . . . . . . . . . . . . . . . 17
8. Privacy Considerations . . . . . . . . . . . . . . . . . . . 18 7. Performance Considerations . . . . . . . . . . . . . . . . . 18
9. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 18 7.1. SIMPLE SHA384 . . . . . . . . . . . . . . . . . . . . . . 18
10. Change Log . . . . . . . . . . . . . . . . . . . . . . . . . 18 8. Privacy Considerations . . . . . . . . . . . . . . . . . . . 19
11. References . . . . . . . . . . . . . . . . . . . . . . . . . 25 9. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 19
11.1. Normative References . . . . . . . . . . . . . . . . . . 25 10. Change Log . . . . . . . . . . . . . . . . . . . . . . . . . 19
11.2. Informative References . . . . . . . . . . . . . . . . . 25 11. References . . . . . . . . . . . . . . . . . . . . . . . . . 26
Appendix A. Example Zones With Digests . . . . . . . . . . . . . 28 11.1. Normative References . . . . . . . . . . . . . . . . . . 26
A.1. Simple EXAMPLE Zone . . . . . . . . . . . . . . . . . . . 28 11.2. Informative References . . . . . . . . . . . . . . . . . 27
A.2. Complex EXAMPLE Zone . . . . . . . . . . . . . . . . . . 28 Appendix A. Example Zones With Digests . . . . . . . . . . . . . 29
A.3. EXAMPLE Zone with multiple digests . . . . . . . . . . . 29 A.1. Simple EXAMPLE Zone . . . . . . . . . . . . . . . . . . . 29
A.4. The URI.ARPA Zone . . . . . . . . . . . . . . . . . . . . 30 A.2. Complex EXAMPLE Zone . . . . . . . . . . . . . . . . . . 30
A.5. The ROOT-SERVERS.NET Zone . . . . . . . . . . . . . . . . 33 A.3. EXAMPLE Zone with multiple digests . . . . . . . . . . . 31
Appendix B. Implementation Status . . . . . . . . . . . . . . . 35 A.4. The URI.ARPA Zone . . . . . . . . . . . . . . . . . . . . 31
B.1. Authors' Implementation . . . . . . . . . . . . . . . . . 35 A.5. The ROOT-SERVERS.NET Zone . . . . . . . . . . . . . . . . 34
B.2. Shane Kerr's Implementation . . . . . . . . . . . . . . . 35 Appendix B. Implementation Status . . . . . . . . . . . . . . . 36
B.3. NIC Chile Labs Implementation . . . . . . . . . . . . . . 36 B.1. Authors' Implementation . . . . . . . . . . . . . . . . . 36
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 36 B.2. Shane Kerr's Implementation . . . . . . . . . . . . . . . 36
B.3. NIC Chile Labs Implementation . . . . . . . . . . . . . . 37
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 37
1. Introduction 1. Introduction
In the DNS, a zone is the collection of authoritative resource In the DNS, a zone is the collection of authoritative resource
records (RRs) sharing a common origin ([RFC8499]). Zones are often records (RRs) sharing a common origin ([RFC8499]). Zones are often
stored as files in the so-called master file format [RFC1034]. Zones stored as files in the so-called master file format [RFC1034]. Zones
are generally distributed among name servers using the AXFR (zone are generally distributed among name servers using the AXFR (zone
transfer [RFC5936]), and IXFR (incremental zone transfer [RFC1995]) transfer [RFC5936]), and IXFR (incremental zone transfer [RFC1995])
protocols. They can also be distributed outside of the DNS, with any 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 file transfer protocol such as FTP, HTTP, and rsync, or even as email
attachments. Currently there is no standard way to verify the attachments. Currently, there is no standard way to compute a hash
authenticity of a stand-alone zone. or message digest for a stand-alone zone.
This document specifies an RR type that provides a cryptographic This document specifies an RR type that provides a cryptographic
message digest of the data in a zone. It allows a receiver of the message digest of the data in a zone. It allows a receiver of the
zone to verify the zone's integrity, and when used in combination zone to verify the zone's integrity, and when used in combination
with DNSSEC, its authenticity. The digest RR is a part of the zone with DNSSEC, its authenticity. The digest RR is a part of the zone
itself, allowing verification of the zone, no matter how it is itself, allowing verification of the zone, no matter how it is
transmitted. The digest uses the wire format of zone data in a transmitted. The digest uses the wire format of zone data in a
canonical ordering. Thus, it is independent of presentation format, canonical ordering. Thus, it is independent of presentation format,
such as whitespace, capitalization, and comments. such as whitespace, capitalization, and comments.
This specification is OPTIONAL to implement by both publishers and This specification is OPTIONAL to implement by both publishers and
consumers of zone data. consumers of zone data.
DNSSEC provides three strong security guarantees relevant to this 1.1. Motivation
protocol:
The 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:
1. whether or not to expect DNSSEC records in the zone, 1. whether or not to expect DNSSEC records in the zone,
2. whether or not to expect a ZONEMD record in a signed zone, and 2. whether or not to expect a ZONEMD record in a signed zone, and
3. whether or not the ZONEMD record has been altered since it was 3. whether or not the ZONEMD record has been altered since it was
signed. signed.
1.1. Motivation A secondary motivation is to provide the equivalent of a checksum,
allowing a zone recipient to check for unintended changes and
The motivation for this protocol enhancement is the desire to verify operational errors, such as accidental truncation.
the authenticity of a stand-alone zone, regardless of how it is
transmitted. A consumer of zone data should be able to verify that
the data is as-published by the zone operator.
1.2. Alternative Approaches 1.2. Alternative Approaches
One approach to preventing data tampering and corruption is to secure One approach to preventing data tampering and corruption is to secure
the distribution channel. The DNS has a number of features that are the distribution channel. The DNS has a number of features that are
already used for channel security. Perhaps the most widely used is already used for channel security. Perhaps the most widely used is
DNS transaction signatures (TSIG [RFC2845]). TSIG uses shared secret DNS transaction signatures (TSIG [RFC2845]). TSIG uses shared secret
keys and a message digest to protect individual query and response keys and a message digest to protect individual query and response
messages. It is generally used to authenticate and validate UPDATE messages. It is generally used to authenticate and validate UPDATE
[RFC2136], AXFR [RFC5936], and IXFR [RFC1995] messages. [RFC2136], AXFR [RFC5936], and IXFR [RFC1995] messages.
DNS Request and Transaction Signatures (SIG(0) [RFC2931]) is another DNS Request and Transaction Signatures (SIG(0) [RFC2931]) is another
protocol extension that authenticates individual DNS transactions. protocol extension that authenticates individual DNS transactions.
Whereas SIG records normally cover specific RR types, SIG(0) is used 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 to sign an entire DNS message. Unlike TSIG, SIG(0) uses public key
cryptography rather than shared secrets. cryptography rather than shared secrets.
The Transport Layer Security protocol suite also provides channel The Transport Layer Security protocol suite also provides channel
security. One can easily imagine the distribution of zones over security. The DPRIVE working group is in the process of specifying
HTTPS-enabled web servers, as well as DNS-over-HTTPS [RFC8484], and DNS Zone Transfer-over-TLS [I-D.ietf-dprive-xfr-over-tls]. One can
perhaps even a future version of DNS-over-TLS ([RFC7858]). also easily imagine the distribution of zones over HTTPS-enabled web
servers, as well as DNS-over-HTTPS [RFC8484].
Unfortunately, the protections provided by these channel security Unfortunately, the protections provided by these channel security
techniques are (in practice) ephemeral and are not retained after the techniques are (in practice) ephemeral and are not retained after the
data transfer is complete. They ensure that the client receives 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 data from the expected server, and that the data sent by the server
is not modified during transmission. However, they do not guarantee is not modified during transmission. However, they do not guarantee
that the server transmits the data as originally published, and do that the server transmits the data as originally published, and do
not provide any methods to verify data that is read after not provide any methods to verify data that is read after
transmission is complete. For example, a name server loading saved transmission is complete. For example, a name server loading saved
zone data upon restart cannot guarantee that the on-disk data has not zone data upon restart cannot guarantee that the on-disk data has not
been modified. Such modification could be the result of an been modified. Such modification could be the result of an
accidental corruption of the file, or perhaps an incompletely saved accidental corruption of the file, or perhaps an incompletely saved
file [disk-full-failure]. For these reasons, it is preferable to file [disk-full-failure]. For these reasons, it is preferable to
secure the data itself. protect the integrity of the data itself.
Why not simply rely on DNSSEC, which provides certain data security Why not simply rely on DNSSEC, which provides certain data security
guarantees? For zones that are signed, a recipient could validate guarantees? For zones that are signed, a recipient could validate
all of the signed RRSets. Additionally, denial-of-existence records all of the signed RRSets. Additionally, denial-of-existence records
prove that RRSets have not been added or removed. However, prove that RRSets have not been added or removed. However,
delegations (non-apex NS records) are not signed by DNSSEC, and delegations (non-apex NS records) are not signed by DNSSEC, and
neither are any glue records. ZONEMD protects the integrity of neither are any glue records. ZONEMD protects the integrity of
delegation, glue, and other records that are not otherwise covered by delegation, glue, and other records that are not otherwise covered by
DNSSEC. Furthermore, zones that employ NSEC3 with opt-out are DNSSEC. Furthermore, zones that employ NSEC3 with opt-out [RFC5155]
susceptible to the removal or addition of names between the signed are susceptible to the removal or addition of names between the
nodes. Whereas DNSSEC is primarily protects consumers of DNS signed nodes. Whereas DNSSEC primarily protects consumers of DNS
response messages, this protocol protects consumers of zones. response messages, this protocol protects consumers of zones.
There are existing tools and protocols that provide data security, There are existing tools and protocols that provide data security,
such as OpenPGP [RFC4880] and S/MIME [RFC5751]. In fact, the such as OpenPGP [RFC4880] and S/MIME [RFC5751]. In fact, the
internic.net site publishes PGP signatures alongside the root zone internic.net site publishes PGP signatures alongside the root zone
and other files available there. However, this is a detached and other files available there. However, this is a detached
signature with no strong association to the corresponding zone file signature with no strong association to the corresponding zone file
other than its timestamp. Non-detached signatures are, of course, other than its timestamp. Non-detached signatures are, of course,
possible, but these necessarily change the format of the file being possible, but these necessarily change the format of the file being
distributed; a zone signed with OpenPGP or S/MIME no longer looks distributed; a zone signed with OpenPGP or S/MIME no longer looks
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message digest of the content of a zone. The digest is calculated at 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 the time of zone publication. If the zone is signed with DNSSEC, any
modifications of the digest can be detected. The procedures for modifications of the digest can be detected. The procedures for
digest calculation and DNSSEC signing are similar. Both require data digest calculation and DNSSEC signing are similar. Both require data
to be processed in a well-defined order and format. It may be to be processed in a well-defined order and format. It may be
possible to perform DNSSEC signing and digest calculation in possible to perform DNSSEC signing and digest calculation in
parallel. parallel.
The zone digest is designed to be used on zones that have infrequent The zone digest is designed to be used on zones that have infrequent
updates. As specified herein, the digest is re-calculated over the updates. As specified herein, the digest is re-calculated over the
entire zone content each time. This specification does not provide entire zone content each time the zone is updated. This
an efficient mechanism for updating the digest on incremental updates specification does not provide an efficient mechanism for updating
of zone data. It is, however, extensible so future schemes to the digest on incremental updates of zone data. It is, however,
support incremental zone digest algorithms (e.g. using Merkle trees) extensible so that future schemes may be defined to support efficient
can be accommodated. incremental digest updates.
It is expected that verification of a zone digest will be implemented 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 in name server software. That is, a name server can verify the zone
data it was given and refuse to serve a zone which fails data it was given and refuse to serve a zone which fails
verification. For signed zones, the name server needs a trust anchor verification. For signed zones, the name server needs a trust anchor
to perform DNSSEC validation. For signed non-root zones, the name to perform DNSSEC validation. For signed non-root zones, the name
server may need to send queries to validate a chain of trust. Digest server may need to send queries to validate a chain of trust. Digest
verification could also be performed externally. verification could also be performed externally.
1.4. Use Cases 1.4. Use Cases
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time. [RFC8806] describes one way to do this. As the root zone time. [RFC8806] describes one way to do this. As the root zone
spreads beyond its traditional deployment boundaries, the spreads beyond its traditional deployment boundaries, the
verification of the completeness of the zone contents becomes more verification of the completeness of the zone contents becomes more
important. important.
1.4.2. Providers, Secondaries, and Anycast 1.4.2. Providers, Secondaries, and Anycast
Since its very early days, the developers of the DNS recognized the Since its very early days, the developers of the DNS recognized the
importance of secondary name servers and service diversity. However, importance of secondary name servers and service diversity. However,
modern DNS service has complex provisioning which includes multiple modern DNS service has complex provisioning which includes multiple
third-party providers and hundreds of anycast instances. Instead of third-party providers ([RFC8901]) and hundreds of anycast instances
a simple primary-to-secondary zone distribution system, today it is ([RFC3258]). Instead of a simple primary-to-secondary zone
possible to have multiple levels, multiple parties, and multiple distribution system, today it is possible to have multiple levels,
protocols involved in the distribution of zone data. This complexity multiple parties, and multiple protocols involved in the distribution
introduces new places for problems to arise. The zone digest of zone data. This complexity introduces new places for problems to
protects the integrity of data that flows through such systems. arise. The zone digest protects the integrity of data that flows
through such systems.
1.4.3. Response Policy Zones 1.4.3. Response Policy Zones
DNS Response Policy Zones is "a method of expressing DNS response A Response Policy Zone (RPZ) is "a mechanism to introduce a
policy information inside specially constructed DNS zones..." [RPZ]. customized policy in Domain Name System servers, so that recursive
A number of companies provide RPZ feeds, which are consumed by name resolvers return possibly modified results" [RPZ]. 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 RPZ zones can be signed with server and firewall products. While RPZ zones can be signed with
DNSSEC, the data is not queried directly, and would not be subject to DNSSEC, the data is not queried directly, and would not be subject to
DNSSEC validation. DNSSEC validation.
1.4.4. Centralized Zone Data Service 1.4.4. Centralized Zone Data Service
ICANN operates the Centralized Zone Data Service [CZDS], which is a ICANN operates the Centralized Zone Data Service [CZDS], which is a
repository of top-level domain zone files. Users that have been repository of top-level domain zone files. Users that have been
granted access are then able to download zone data. Adding a zone granted access are then able to download zone data. Adding a zone
digest to these would provide CZDS users with assurances that the digest to these would provide CZDS users with assurances that the
data has not been modified between origination and retrieval. ZONEMD data has not been modified between origination and retrieval. Note
could be added to CZDS zone data independently of the zone served by that ZONEMD could be added to zone data supplied to CZDS without
production name servers. 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.
1.4.5. General Purpose Comparison Check 1.4.5. General Purpose Comparison Check
Since the zone digest calculation does not depend on presentation Since the zone digest calculation does not depend on presentation
format, it could be used to compare multiple copies of a zone format, it could be used to compare multiple copies of a zone
received from different sources, or copies generated by different received from different sources, or copies generated by different
processes. processes. In this case, it serves as a checksum and can be useful
even for unsigned zones.
1.5. Terminology 1.5. Terminology
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and
"OPTIONAL" in this document are to be interpreted as described in BCP "OPTIONAL" in this document are to be interpreted as described in BCP
14 [RFC2119] [RFC8174] when, and only when, they appear in all 14 [RFC2119] [RFC8174] when, and only when, they appear in all
capitals, as shown here. capitals, as shown here.
The terms Private Use, Reserved, Unassigned, and Specification The terms Private Use, Reserved, Unassigned, and Specification
skipping to change at page 8, line 8 skipping to change at page 8, line 25
2. The ZONEMD Resource Record 2. The ZONEMD Resource Record
This section describes the ZONEMD Resource Record, including its This section describes the ZONEMD Resource Record, including its
fields, wire format, and presentation format. The Type value for the fields, wire format, and presentation format. The Type value for the
ZONEMD RR is 63. The ZONEMD RR is class independent. The RDATA of ZONEMD RR is 63. The ZONEMD RR is class independent. The RDATA of
the resource record consists of four fields: Serial, Scheme, Hash the resource record consists of four fields: Serial, Scheme, Hash
Algorithm, and Digest. Algorithm, and Digest.
A zone MAY contain multiple ZONEMD RRs to support algorithm agility A zone MAY contain multiple ZONEMD RRs to support algorithm agility
[RFC7696] and rollovers. When multiple ZONEMD RRs are present, each [RFC7696]. [RFC Editor: change that to BCP 201] When multiple ZONEMD
must specify a unique Scheme and Hash Algorithm tuple. It is RRs are present, each MUST specify a unique Scheme and Hash Algorithm
RECOMMENDED that a zone include only one ZONEMD RR, unless the zone tuple. It is RECOMMENDED that a zone include only one ZONEMD RR,
publisher is in the process of transitioning to a new Scheme or Hash unless the zone publisher is in the process of transitioning to a new
Algorithm. Scheme or Hash Algorithm.
2.1. Non-apex ZONEMD Records 2.1. Non-apex ZONEMD Records
This document specifies ZONEMD RRs located at the zone apex. Non- This document specifies ZONEMD RRs located at the zone apex. Non-
apex ZONEMD RRs are not forbidden, but have no meaning in this apex ZONEMD RRs are not forbidden, but have no meaning in this
specification. Non-apex ZONEMD RRs MUST NOT be used for specification. Non-apex ZONEMD RRs MUST NOT be used for
verification. verification.
During digest calculation, non-apex ZONEMD RRs are treated as During digest calculation, non-apex ZONEMD RRs are treated as
ordinary RRs. They are digested as-is and the RR is not replaced by ordinary RRs. They are digested as-is and the RR is not replaced by
skipping to change at page 9, line 13 skipping to change at page 9, line 34
version of the zone's content. Without the serial number, a stand- version of the zone's content. Without the serial number, a stand-
alone ZONEMD digest has no obvious association to any particular alone ZONEMD digest has no obvious association to any particular
instance of a zone. instance of a zone.
2.2.2. The Scheme Field 2.2.2. The Scheme Field
The Scheme field is an 8-bit unsigned integer that identifies the The Scheme field is an 8-bit unsigned integer that identifies the
methods by which data is collated and presented as input to the methods by which data is collated and presented as input to the
hashing function. hashing function.
Herein, SIMPLE, with value 1, is the only standardized Scheme defined Herein, SIMPLE, with Hash Algorithm value 1, is the only standardized
for ZONEMD records and it MUST be implemented. The Scheme registry Scheme defined for ZONEMD records and it MUST be implemented. The
is further described in Section 5. Scheme registry is further described in Section 5.
Scheme values 240-254 are allocated for Private Use. Scheme values 240-254 are allocated for Private Use.
2.2.3. The Hash Algorithm Field 2.2.3. The Hash Algorithm Field
The Hash Algorithm field is an 8-bit unsigned integer that identifies The Hash Algorithm field is an 8-bit unsigned integer that identifies
the cryptographic hash algorithm used to construct the digest. the cryptographic hash algorithm used to construct the digest.
Herein, SHA384 [RFC6234], with value 1, is the only standardized Hash Herein, SHA384 [RFC6234], with value 1, is the only standardized Hash
Algorithm defined for ZONEMD records that MUST be implemented. When Algorithm defined for ZONEMD records that MUST be implemented. When
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2.4. ZONEMD Example 2.4. ZONEMD Example
The following example shows a ZONEMD RR in presentation format: The following example shows a ZONEMD RR in presentation format:
example.com. 86400 IN ZONEMD 2018031500 1 1 ( example.com. 86400 IN ZONEMD 2018031500 1 1 (
FEBE3D4CE2EC2FFA4BA99D46CD69D6D29711E55217057BEE FEBE3D4CE2EC2FFA4BA99D46CD69D6D29711E55217057BEE
7EB1A7B641A47BA7FED2DD5B97AE499FAFA4F22C6BD647DE ) 7EB1A7B641A47BA7FED2DD5B97AE499FAFA4F22C6BD647DE )
3. Calculating the Digest 3. 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 identical ZONEMD RRs,
signatures, and dential-of-existence records are produced.
3.1. Add ZONEMD Placeholder 3.1. Add ZONEMD Placeholder
In preparation for calculating the zone digest, any existing ZONEMD In preparation for calculating the zone digest(s), any existing
records (and covering RRSIGs) at the zone apex are first deleted. ZONEMD records (and covering RRSIGs) at the zone apex are first
deleted.
Prior to calculation of the digest, and prior to signing with DNSSEC, Prior to calculation of the digest, and prior to signing with DNSSEC,
one or more placeholder ZONEMD records are added to the zone apex. one or more placeholder ZONEMD records are added to the zone apex.
This ensures that denial-of-existence (NSEC, NSEC3) records are This ensures that denial-of-existence (NSEC, NSEC3) records are
created correctly if the zone is signed with DNSSEC. If placeholders created correctly if the zone is signed with DNSSEC. If placeholders
were not added prior to signing, the later addition of ZONEMD records 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/ would also require updating the Type Bit Maps field of any apex NSEC/
NSEC3 RRs, which then invalidates the calculated digest value. NSEC3 RRs, which then invalidates the calculated digest value.
When multiple ZONEMD RRs are published in the zone, e.g., during an When multiple ZONEMD RRs are published in the zone, e.g., during an
skipping to change at page 11, line 38 skipping to change at page 12, line 18
schemes may be defined in future updates to this document. schemes may be defined in future updates to this document.
3.3.1. The SIMPLE Scheme 3.3.1. The SIMPLE Scheme
For the SIMPLE scheme, the digest is calculated over the zone as a 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 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 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 probably is a good choice for zones that are small and/or stable, but probably
not good for zones that are large and/or dynamic. not good for zones that are large and/or dynamic.
Calculation of a zone digest REQUIRES RRs to be processed in a Calculation of a zone digest requires RRs to be processed in a
consistent format and ordering. This specification uses DNSSEC's consistent format and ordering. This specification uses DNSSEC's
canonical on-the-wire RR format (without name compression) and canonical on-the-wire RR format (without name compression) and
ordering as specified in Sections 6.1, 6.2, and 6.3 of [RFC4034] with ordering as specified in Sections 6.1, 6.2, and 6.3 of [RFC4034] with
the additional provision that RRSets having the same owner name MUST the additional provision that RRSets having the same owner name MUST
be numerically ordered, in ascending order, by their numeric RR TYPE. be numerically ordered, in ascending order, by their numeric RR TYPE.
3.3.1.1. SIMPLE Scheme Inclusion/Exclusion Rules 3.3.1.1. SIMPLE Scheme Inclusion/Exclusion Rules
When iterating over records in the zone, the following inclusion/ When iterating over records in the zone, the following inclusion/
exclusion rules apply: exclusion rules apply:
o All records in the zone, including glue records, MUST be included. o All records in the zone, including glue records, MUST be included,
unless excluded by a subsequent rule.
o Occluded data ([RFC5936] Section 3.5) MUST be included. o Occluded data ([RFC5936] Section 3.5) MUST be included.
o If there are duplicate RRs with equal owner, class, type, and o If there are duplicate RRs with equal owner, class, type, and
RDATA, only one instance is included ([RFC4034] Section 6.3), and RDATA, only one instance is included ([RFC4034] Section 6.3), and
the duplicates MUST be omitted. the duplicates MUST be omitted.
o The placeholder apex ZONEMD RR(s) MUST NOT be included. o The placeholder apex ZONEMD RR(s) MUST NOT be included.
o If the zone is signed, DNSSEC RRs MUST be included, except: o If the zone is signed, DNSSEC RRs MUST be included, except:
skipping to change at page 13, line 7 skipping to change at page 13, line 36
The recipient of a zone that has a ZONEMD RR verifies the zone by The recipient of a zone that has a ZONEMD RR verifies the zone by
calculating the digest as follows. If multiple ZONEMD RRs are calculating the digest as follows. If multiple ZONEMD RRs are
present in the zone, e.g., during an algorithm rollover, a match present in the zone, e.g., during an algorithm rollover, a match
using any one of the recipient's supported Schemes and Hash using any one of the recipient's supported Schemes and Hash
Algorithms is sufficient to verify the zone. The verifier MAY ignore Algorithms is sufficient to verify the zone. The verifier MAY ignore
a ZONEMD RR if its Scheme and Hash Algorithm violates local policy. a ZONEMD RR if its Scheme and Hash Algorithm violates local policy.
1. The verifier MUST first determine whether or not to expect DNSSEC 1. The verifier MUST first determine whether or not to expect DNSSEC
records in the zone. This is done by examining locally records in the zone. This is done by examining locally
configured trust anchors, or querying for (and validating) DS RRs configured trust anchors, and, if necessary, querying for (and
in the parent zone. For zones that are provably insecure, or if validating) DS RRs in the anchors, or querying for (and
DNSSEC validation is not performed, digest verification continues validating) DS RRs in the parent zone. For zones that are
at step 4 below. provably insecure, or if DNSSEC validation is not performed,
digest verification continues at step 4 below.
2. For zones that are provably secure, the existence of the apex 2. For zones that are provably secure, the existence of the apex
ZONEMD record MUST be verified. If the ZONEMD record provably ZONEMD record MUST be verified. If the ZONEMD record provably
does not exist, digest verification cannot occur. If the ZONEMD does not exist, digest verification cannot occur. If the ZONEMD
record does provably exist, but is not found in the zone, digest record does provably exist, but is not found in the zone, digest
verification MUST NOT be considered successful. verification MUST NOT be considered successful.
3. For zones that are provably secure, the SOA and ZONEMD RRSets 3. For zones that are provably secure, the SOA and ZONEMD RRSets
MUST have valid signatures, chaining up to a trust anchor. If MUST have valid signatures, chaining up to a trust anchor. If
DNSSEC validation of the SOA or ZONEMD records fails, digest DNSSEC validation of the SOA or ZONEMD records fails, digest
skipping to change at page 14, line 16 skipping to change at page 14, line 46
E. The zone digest is computed over the zone data as described E. The zone digest is computed over the zone data as described
in Section 3.3, using the Scheme and Hash Algorithm for the in Section 3.3, using the Scheme and Hash Algorithm for the
current ZONEMD RR. current ZONEMD RR.
F. The computed digest is compared to the received digest. If F. The computed digest is compared to the received digest. If
the two digest values match, verification is considered the two digest values match, verification is considered
successful. Otherwise, verification MUST NOT be considered successful. Otherwise, verification MUST NOT be considered
successful for this ZONEMD RR. successful for this ZONEMD RR.
[ Maybe remove all the "SHOULD report" above and just say this:]
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.
5. IANA Considerations 5. IANA Considerations
5.1. ZONEMD RRtype 5.1. ZONEMD RRtype
This document defines a new DNS RR type, ZONEMD, whose value 63 has This document defines a new DNS RR type, ZONEMD, whose value 63 has
been allocated by IANA from the "Resource Record (RR) TYPEs" been allocated by IANA from the "Resource Record (RR) TYPEs"
subregistry of the "Domain Name System (DNS) Parameters" registry: subregistry of the "Domain Name System (DNS) Parameters" registry:
Type: ZONEMD Type: ZONEMD
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5.2. ZONEMD Scheme 5.2. ZONEMD Scheme
IANA is requested to create a new registry on the "Domain Name System IANA is requested to create a new registry on the "Domain Name System
(DNS) Parameters" web page as follows: (DNS) Parameters" web page as follows:
Registry Name: ZONEMD Schemes Registry Name: ZONEMD Schemes
Registration Procedure: Specification Required Registration Procedure: Specification Required
Reference: [this document] Reference: [this document]
+---------+---------------+----------+------------------+-----------+
| Value | Description | Mnemonic | Implementation | Reference | +---------+-------------------------+----------+-----------------+
| | | | Requirement | | | Value | Description | Mnemonic | Reference |
+---------+---------------+----------+------------------+-----------+ +---------+-------------------------+----------+-----------------+
| 0 | Reserved | | | | | 0 | Reserved | | |
| 1 | Simple ZONEMD | SIMPLE | MUST | [this | | 1 | Simple ZONEMD collation | SIMPLE | [this document] |
| | collation | | | document] | | 2-239 | Unassigned | | |
| 2-239 | Unassigned | | | | | 240-254 | Private Use | N/A | [this document] |
| 240-254 | Private Use | N/A | N/A | [this | | 255 | Reserved | | |
| | | | | document] | +---------+-------------------------+----------+-----------------+
| 255 | Reserved | | | |
+---------+---------------+----------+------------------+-----------+
Table 1: ZONEMD Scheme Registry Table 1: ZONEMD Scheme Registry
5.3. ZONEMD Hash Algorithm 5.3. ZONEMD Hash Algorithm
IANA is requested to create a new registry on the "Domain Name System IANA is requested to create a new registry on the "Domain Name System
(DNS) Parameters" web page as follows: (DNS) Parameters" web page as follows:
Registry Name: ZONEMD Hash Algorithms Registry Name: ZONEMD Hash Algorithms
skipping to change at page 15, line 27 skipping to change at page 16, line 4
Table 1: ZONEMD Scheme Registry Table 1: ZONEMD Scheme Registry
5.3. ZONEMD Hash Algorithm 5.3. ZONEMD Hash Algorithm
IANA is requested to create a new registry on the "Domain Name System IANA is requested to create a new registry on the "Domain Name System
(DNS) Parameters" web page as follows: (DNS) Parameters" web page as follows:
Registry Name: ZONEMD Hash Algorithms Registry Name: ZONEMD Hash Algorithms
Registration Procedure: Specification Required Registration Procedure: Specification Required
Reference: [this document] Reference: [this document]
+---------+-------------+----------+-------------------+------------+ +---------+-------------+----------+-----------------+
| Value | Description | Mnemonic | Implementation | Reference | | Value | Description | Mnemonic | Reference |
| | | | Requirement | | +---------+-------------+----------+-----------------+
+---------+-------------+----------+-------------------+------------+ | 0 | Reserved | | |
| 0 | Reserved | | | | | 1 | SHA-384 | SHA384 | [this document] |
| 1 | SHA-384 | SHA384 | MUST | [this | | 2 | SHA-512 | SHA512 | [this document] |
| | | | | document] | | 3-239 | Unassigned | | |
| 2 | SHA-512 | SHA512 | SHOULD | [this | | 240-254 | Private Use | N/A | [his document] |
| | | | | document] | | 255 | Reserved | | |
| 3-239 | Unassigned | | | | +---------+-------------+----------+-----------------+
| 240-254 | Private Use | N/A | N/A | [his |
| | | | | document] |
| 255 | Reserved | | | |
+---------+-------------+----------+-------------------+------------+
Table 2: ZONEMD Hash Algorithm Registry Table 2: ZONEMD Hash Algorithm Registry
6. Security Considerations 6. Security Considerations
6.1. Attacks Against the Zone Digest
The zone digest allows the recipient of a zone to verify its 6.1. Using Zone Digest Without DNSSEC
integrity. In conjunction with DNSSEC, the recipient can
authenticate that it is as published by the zone originator. 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 Digest field
of a ZONEMD RR.
6.2. Attacks Against the Zone Digest
An attacker, whose goal is to modify zone content before it is used An attacker, whose goal is to modify zone content before it is used
by the victim, may consider a number of different approaches. by the victim, may consider a number of different approaches.
The attacker might perform a downgrade attack to an unsigned zone. The attacker might perform a downgrade attack to an unsigned zone.
This is why Section 4 talks about determining whether or not to This is why Section 4 talks about determining whether or not to
expect DNSSEC signatures for the zone in step 1. expect DNSSEC signatures for the zone in step 1.
The attacker might perform a downgrade attack by removing one or more The attacker might perform a downgrade attack by removing one or more
ZONEMD records. Such a removal is detectable only with DNSSEC ZONEMD records. Such a removal is detectable only with DNSSEC
validation and is why Section 4 talks about checking denial-of- validation and is why Section 4 talks about checking denial-of-
existence proofs in step 2 and signature validation in step 3. existence proofs in step 2 and signature validation in step 3.
The attacker might alter the Scheme, Hash Algorithm, or Digest fields The attacker might alter the Scheme, Hash Algorithm, or Digest fields
of the ZONEMD record. Such modifications are detectable only with of the ZONEMD record. Such modifications are detectable only with
DNSSEC validation. DNSSEC validation.
6.2. DNSSESC Timing Considerations As stated in [RFC7696], 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.
6.3. 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,
Section 2 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.
6.4. DNSSEC Timing Considerations
As with all DNSSEC signatures, the ability to perform signature As with all DNSSEC signatures, the ability to perform signature
validation of a ZONEMD record is limited in time. If the DS 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 record(s) or trust anchors for the zone to be verified are no longer
available, the recipient cannot validate the ZONEMD RRSet. This available, the recipient cannot validate the ZONEMD RRSet. This
could happen even if the ZONEMD signature is still current (not could happen even if the ZONEMD signature is still current (not
expired), since the zone's DS record(s) may have been withdrawn expired), since the zone's DS record(s) may have been withdrawn
following a Key Signing Key (KSK) rollover. following a Key Signing Key (KSK) rollover.
For zones where it may be important to validate a ZONEMD RRSet For zones where it may be important to validate a ZONEMD RRSet
through its entire signature validity period, the zone operator through its entire signature validity period, the zone operator
should ensure that KSK rollover timing takes this into consideration. should ensure that KSK rollover timing takes this into consideration.
6.3. Attacks Utilizing ZONEMD Queries 6.5. Attacks Utilizing ZONEMD Queries
Nothing in this specification prevents clients from making, and Nothing in this specification prevents clients from making, and
servers from responding to, ZONEMD queries. Servers SHOULD NOT servers from responding to, ZONEMD queries. Servers SHOULD NOT
calculate zone digests dynamically (for each query) as this can be calculate zone digests dynamically (for each query) as this can be
used as a CPU resource exhaustion attack. used as a CPU resource exhaustion attack.
ZONEMD responses could be used in a distributed denial-of-service ZONEMD responses could be used in a distributed denial-of-service
amplification attack. The ZONEMD RR is moderately sized, much like amplification attack. The ZONEMD RR is moderately sized, much like
the DS RR. A single ZONEMD RR contributes approximately 65 to 95 the DS RR. A single ZONEMD RR contributes approximately 65 to 95
octets to a DNS response, for digest types defined herein. Other RR octets to a DNS response, for digest types defined herein. Other RR
types, such as DNSKEY, can result in larger amplification effects. types, such as DNSKEY, can result in larger amplification effects.
6.4. Resilience and Fragility 6.6. Resilience and Fragility
ZONEMD is used to detect incomplete or corrupted zone data prior to ZONEMD is used to detect incomplete or corrupted zone data prior to
its use, thereby increasing resilience by not using corrupt data, but its use, thereby increasing resilience by not using corrupt data, but
also introduces some denial-of-service fragility by making good data also introduces some denial-of-service fragility by making good data
in a zone unavailable if some other data is missing or corrupt. in a zone unavailable if some other data is missing or corrupt.
Publishers and consumers of zones containing ZONEMD records should be Publishers and consumers of zones containing ZONEMD records should be
aware of these tradeoffs. While the intention is to secure the zone aware of these tradeoffs. While the intention is to secure the zone
data, misconfigurations or implementation bugs are generally data, misconfigurations or implementation bugs are generally
indistinguishable from intentional tampering, and could lead to indistinguishable from intentional tampering, and could lead to
service failures when verification is performed automatically. service failures when verification is performed automatically.
skipping to change at page 18, line 41 skipping to change at page 19, line 25
9. Acknowledgments 9. Acknowledgments
The authors wish to thank David Blacka, Scott Hollenbeck, and Rick The authors wish to thank David Blacka, Scott Hollenbeck, and Rick
Wilhelm for providing feedback on early drafts of this document. Wilhelm for providing feedback on early drafts of this document.
Additionally, they thank Joe Abley, Mark Andrews, Ralph Dolmans, Additionally, they thank Joe Abley, Mark Andrews, Ralph Dolmans,
Donald Eastlake, Richard Gibson, Olafur Gudmundsson, Bob Harold, Paul Donald Eastlake, Richard Gibson, Olafur Gudmundsson, Bob Harold, Paul
Hoffman, Evan Hunt, Shumon Huque, Tatuya Jinmei, Mike St. Johns, Burt Hoffman, Evan Hunt, Shumon Huque, Tatuya Jinmei, Mike St. Johns, Burt
Kaliski, Shane Kerr, Matt Larson, Barry Leiba, John Levine, Ed Lewis, Kaliski, Shane Kerr, Matt Larson, Barry Leiba, John Levine, Ed Lewis,
Matt Pounsett, Mukund Sivaraman, Petr Spacek, Ondrej Sury, Willem Matt Pounsett, Mukund Sivaraman, Petr Spacek, Ondrej Sury, Willem
Toorop, Florian Weimer, Tim Wicinski, Wouter Wijngaards, Paul Toorop, Florian Weimer, Tim Wicinski, Wouter Wijngaards, Paul
Wouters, and other members of the DNS working group for their input. Wouters, and other members of the DNSOP working group for their
input.
10. Change Log 10. Change Log
RFC Editor: Please remove this section before publication. RFC Editor: Please remove this section before publication.
This section lists substantial changes to the document as it is being This section lists substantial changes to the document as it is being
worked on. worked on.
From -00 to -01: From -00 to -01:
skipping to change at page 25, line 11 skipping to change at page 25, line 47
o SECDIR review: Forgot to delete sentence about IANA policy for o SECDIR review: Forgot to delete sentence about IANA policy for
adding new hash algorithms. adding new hash algorithms.
o SECDIR review: Spell out Key Signing Key first time. o SECDIR review: Spell out Key Signing Key first time.
o SECDIR review: say "private use hash algorithm code points." o SECDIR review: say "private use hash algorithm code points."
o SECDIR review: Update estimates of ZONEMD RR size. o SECDIR review: Update estimates of ZONEMD RR size.
From -12 to -13:
o Added reference to draft-ietf-dprive-xfr-over-tls.
o Dropped Implementation Requirement from registry tables.
o Added Use of Multiple ZONEMD Hash Algorithms to Security
Considerations.
o Added Using Zone Digest Without DNSSEC to Security Considerations.
o Added notes about the need for algorithm agility due to crypto
algorithm aging.
o Further clarified that only with DNSSEC can ZONEMD guarantee
integrity and authenticity.
o For unsigned zones, ZONEMD serves only as a checksum.
o Calculation algorithm is designed for common case of offline
signing. Deviations may be allowed as long as the end result is
the same.
o Numerous small edits and clarifications from IESG reviewer
comments.
11. References 11. References
11.1. Normative References 11.1. Normative References
[RFC1034] Mockapetris, P., "Domain names - concepts and facilities", [RFC1034] Mockapetris, P., "Domain names - concepts and facilities",
STD 13, RFC 1034, DOI 10.17487/RFC1034, November 1987, STD 13, RFC 1034, DOI 10.17487/RFC1034, November 1987,
<https://www.rfc-editor.org/info/rfc1034>. <https://www.rfc-editor.org/info/rfc1034>.
[RFC1035] Mockapetris, P., "Domain names - implementation and [RFC1035] Mockapetris, P., "Domain names - implementation and
specification", STD 13, RFC 1035, DOI 10.17487/RFC1035, specification", STD 13, RFC 1035, DOI 10.17487/RFC1035,
skipping to change at page 26, line 10 skipping to change at page 27, line 26
DENIC, "Background of the Partial Failure of the Name DENIC, "Background of the Partial Failure of the Name
Service for .de Domains", May 2010, Service for .de Domains", May 2010,
<https://web.archive.org/web/20100618032705/ <https://web.archive.org/web/20100618032705/
https://www.denic.de/en/denic-in-dialogue/news/2733.html>. https://www.denic.de/en/denic-in-dialogue/news/2733.html>.
[DnsTools] [DnsTools]
NIC Chile Labs, "DNS tools for zone signature (file, NIC Chile Labs, "DNS tools for zone signature (file,
pkcs11-hsm) and validation, and zone digest (ZONEMD)", pkcs11-hsm) and validation, and zone digest (ZONEMD)",
April 2020, <https://github.com/niclabs/dns-tools>. April 2020, <https://github.com/niclabs/dns-tools>.
[I-D.ietf-dprive-xfr-over-tls]
Toorop, W., Dickinson, S., Sahib, S., Aras, P., and A.
Mankin, "DNS Zone Transfer-over-TLS", draft-ietf-dprive-
xfr-over-tls-02 (work in progress), July 2020.
[InterNIC] [InterNIC]
ICANN, "InterNIC FTP site", May 2018, ICANN, "InterNIC FTP site", May 2018,
<ftp://ftp.internic.net/domain/>. <ftp://ftp.internic.net/domain/>.
[ldns-zone-digest] [ldns-zone-digest]
Verisign, "Implementation of Message Digests for DNS Zones Verisign, "Implementation of Message Digests for DNS Zones
using the ldns library", July 2018, using the ldns library", July 2018,
<https://github.com/verisign/ldns-zone-digest>. <https://github.com/verisign/ldns-zone-digest>.
[RFC1995] Ohta, M., "Incremental Zone Transfer in DNS", RFC 1995, [RFC1995] Ohta, M., "Incremental Zone Transfer in DNS", RFC 1995,
skipping to change at page 26, line 45 skipping to change at page 28, line 18
[RFC2845] Vixie, P., Gudmundsson, O., Eastlake 3rd, D., and B. [RFC2845] Vixie, P., Gudmundsson, O., Eastlake 3rd, D., and B.
Wellington, "Secret Key Transaction Authentication for DNS Wellington, "Secret Key Transaction Authentication for DNS
(TSIG)", RFC 2845, DOI 10.17487/RFC2845, May 2000, (TSIG)", RFC 2845, DOI 10.17487/RFC2845, May 2000,
<https://www.rfc-editor.org/info/rfc2845>. <https://www.rfc-editor.org/info/rfc2845>.
[RFC2931] Eastlake 3rd, D., "DNS Request and Transaction Signatures [RFC2931] Eastlake 3rd, D., "DNS Request and Transaction Signatures
( SIG(0)s )", RFC 2931, DOI 10.17487/RFC2931, September ( SIG(0)s )", RFC 2931, DOI 10.17487/RFC2931, September
2000, <https://www.rfc-editor.org/info/rfc2931>. 2000, <https://www.rfc-editor.org/info/rfc2931>.
[RFC3258] Hardie, T., "Distributing Authoritative Name Servers via
Shared Unicast Addresses", RFC 3258, DOI 10.17487/RFC3258,
April 2002, <https://www.rfc-editor.org/info/rfc3258>.
[RFC4880] Callas, J., Donnerhacke, L., Finney, H., Shaw, D., and R. [RFC4880] Callas, J., Donnerhacke, L., Finney, H., Shaw, D., and R.
Thayer, "OpenPGP Message Format", RFC 4880, Thayer, "OpenPGP Message Format", RFC 4880,
DOI 10.17487/RFC4880, November 2007, DOI 10.17487/RFC4880, November 2007,
<https://www.rfc-editor.org/info/rfc4880>. <https://www.rfc-editor.org/info/rfc4880>.
[RFC5155] Laurie, B., Sisson, G., Arends, R., and D. Blacka, "DNS
Security (DNSSEC) Hashed Authenticated Denial of
Existence", RFC 5155, DOI 10.17487/RFC5155, March 2008,
<https://www.rfc-editor.org/info/rfc5155>.
[RFC5751] Ramsdell, B. and S. Turner, "Secure/Multipurpose Internet [RFC5751] Ramsdell, B. and S. Turner, "Secure/Multipurpose Internet
Mail Extensions (S/MIME) Version 3.2 Message Mail Extensions (S/MIME) Version 3.2 Message
Specification", RFC 5751, DOI 10.17487/RFC5751, January Specification", RFC 5751, DOI 10.17487/RFC5751, January
2010, <https://www.rfc-editor.org/info/rfc5751>. 2010, <https://www.rfc-editor.org/info/rfc5751>.
[RFC5936] Lewis, E. and A. Hoenes, Ed., "DNS Zone Transfer Protocol [RFC5936] Lewis, E. and A. Hoenes, Ed., "DNS Zone Transfer Protocol
(AXFR)", RFC 5936, DOI 10.17487/RFC5936, June 2010, (AXFR)", RFC 5936, DOI 10.17487/RFC5936, June 2010,
<https://www.rfc-editor.org/info/rfc5936>. <https://www.rfc-editor.org/info/rfc5936>.
[RFC7696] Housley, R., "Guidelines for Cryptographic Algorithm [RFC7696] Housley, R., "Guidelines for Cryptographic Algorithm
Agility and Selecting Mandatory-to-Implement Algorithms", Agility and Selecting Mandatory-to-Implement Algorithms",
BCP 201, RFC 7696, DOI 10.17487/RFC7696, November 2015, BCP 201, RFC 7696, DOI 10.17487/RFC7696, November 2015,
<https://www.rfc-editor.org/info/rfc7696>. <https://www.rfc-editor.org/info/rfc7696>.
[RFC7858] Hu, Z., Zhu, L., Heidemann, J., Mankin, A., Wessels, D.,
and P. Hoffman, "Specification for DNS over Transport
Layer Security (TLS)", RFC 7858, DOI 10.17487/RFC7858, May
2016, <https://www.rfc-editor.org/info/rfc7858>.
[RFC8126] Cotton, M., Leiba, B., and T. Narten, "Guidelines for [RFC8126] Cotton, M., Leiba, B., and T. Narten, "Guidelines for
Writing an IANA Considerations Section in RFCs", BCP 26, Writing an IANA Considerations Section in RFCs", BCP 26,
RFC 8126, DOI 10.17487/RFC8126, June 2017, RFC 8126, DOI 10.17487/RFC8126, June 2017,
<https://www.rfc-editor.org/info/rfc8126>. <https://www.rfc-editor.org/info/rfc8126>.
[RFC8484] Hoffman, P. and P. McManus, "DNS Queries over HTTPS [RFC8484] Hoffman, P. and P. McManus, "DNS Queries over HTTPS
(DoH)", RFC 8484, DOI 10.17487/RFC8484, October 2018, (DoH)", RFC 8484, DOI 10.17487/RFC8484, October 2018,
<https://www.rfc-editor.org/info/rfc8484>. <https://www.rfc-editor.org/info/rfc8484>.
[RFC8499] Hoffman, P., Sullivan, A., and K. Fujiwara, "DNS [RFC8499] Hoffman, P., Sullivan, A., and K. Fujiwara, "DNS
Terminology", BCP 219, RFC 8499, DOI 10.17487/RFC8499, Terminology", BCP 219, RFC 8499, DOI 10.17487/RFC8499,
January 2019, <https://www.rfc-editor.org/info/rfc8499>. January 2019, <https://www.rfc-editor.org/info/rfc8499>.
[RFC8806] Kumari, W. and P. Hoffman, "Running a Root Server Local to [RFC8806] Kumari, W. and P. Hoffman, "Running a Root Server Local to
a Resolver", RFC 8806, DOI 10.17487/RFC8806, June 2020, a Resolver", RFC 8806, DOI 10.17487/RFC8806, June 2020,
<https://www.rfc-editor.org/info/rfc8806>. <https://www.rfc-editor.org/info/rfc8806>.
[RFC8901] Huque, S., Aras, P., Dickinson, J., Vcelak, J., and D.
Blacka, "Multi-Signer DNSSEC Models", RFC 8901,
DOI 10.17487/RFC8901, September 2020,
<https://www.rfc-editor.org/info/rfc8901>.
[RootServers] [RootServers]
Root Server Operators, "Root Server Technical Operations", Root Server Operators, "Root Server Technical Operations",
July 2018, <https://www.root-servers.org/>. July 2018, <https://www.root-servers.org/>.
[RPZ] Vixie, P. and V. Schryver, "DNS Response Policy Zones [RPZ] Wikipedia, "Response policy zone", May 2020,
(RPZ)", draft-vixie-dnsop-dns-rpz-00 (work in progress), <https://en.wikipedia.org/w/
June 2018, <https://tools.ietf.org/html/draft-vixie-dnsop- index.php?title=Response_policy_zone&oldid=960043728>.
dns-rpz-00>.
[ZoneDigestHackathon] [ZoneDigestHackathon]
Kerr, S., "Prototype implementation of ZONEMD for the IETF Kerr, S., "Prototype implementation of ZONEMD for the IETF
102 hackathon in Python", July 2018, 102 hackathon in Python", July 2018,
<https://github.com/shane-kerr/ZoneDigestHackathon>. <https://github.com/shane-kerr/ZoneDigestHackathon>.
Appendix A. Example Zones With Digests Appendix A. Example Zones With Digests
This appendix contains example zones with accurate ZONEMD records. This appendix contains example zones with accurate ZONEMD records.
These can be used to verify an implementation of the zone digest These can be used to verify an implementation of the zone digest
skipping to change at page 35, line 10 skipping to change at page 36, line 10
nstld.verisign-grs.com. 2018091100 14400 7200 1209600 3600000 ) nstld.verisign-grs.com. 2018091100 14400 7200 1209600 3600000 )
root-servers.net. 3600000 IN ZONEMD 2018091100 1 1 ( root-servers.net. 3600000 IN ZONEMD 2018091100 1 1 (
f1ca0ccd91bd5573d9f431c00ee0101b2545c97602be0a97 f1ca0ccd91bd5573d9f431c00ee0101b2545c97602be0a97
8a3b11dbfc1c776d5b3e86ae3d973d6b5349ba7f04340f79 ) 8a3b11dbfc1c776d5b3e86ae3d973d6b5349ba7f04340f79 )
Appendix B. Implementation Status Appendix B. Implementation Status
RFC Editor: Please retain this section upon publication. RFC Editor: Please retain this section upon publication.
This section records the status of known implementations of the This section records the status of known implementations of the
protocol defined by this specification at the time of posting of this protocol defined by this specification at the time of publication,
Internet-Draft, and is based on a proposal described in RFC 7942. and is inspired by the concepts described in RFC7942.
The description of implementations in this section is intended to
assist the IETF in its decision processes in progressing drafts to Please note that the listing of any individual implementation here
RFCs. Please note that the listing of any individual implementation does not imply endorsement by the IETF. Furthermore, no effort has
here does not imply endorsement by the IETF. Furthermore, no effort been spent to verify the information presented here that was supplied
has been spent to verify the information presented here that was by IETF contributors. This is not intended as, and must not be
supplied by IETF contributors. This is not intended as, and must not construed to be, a catalog of available implementations or their
be construed to be, a catalog of available implementations or their
features. Readers are advised to note that other implementations may features. Readers are advised to note that other implementations may
exist. exist.
B.1. Authors' Implementation B.1. Authors' Implementation
The authors have an open source implementation in C, using the ldns The authors have an open source implementation in C, using the ldns
library [ldns-zone-digest]. This implementation is able to perform library [ldns-zone-digest]. This implementation is able to perform
the following functions: the following functions:
o Read an input zone and output a zone with the ZONEMD placeholder. o Read an input zone and output a zone with the ZONEMD placeholder.
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