draft-wessels-dns-zone-digest-02.txt   draft-wessels-dns-zone-digest-03.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 M. Weinberg Intended status: Experimental M. Weinberg
Expires: January 3, 2019 Verisign Expires: April 12, 2019 Verisign
W. Kumari W. Kumari
Google Google
W. Hardaker W. Hardaker
USC/ISI USC/ISI
July 2, 2018 October 9, 2018
Message Digest for DNS Zones Message Digest for DNS Zones
draft-wessels-dns-zone-digest-02 draft-wessels-dns-zone-digest-03
Abstract Abstract
This document describes a protocol and DNS Resource Record used to This document describes an experimental protocol and new DNS Resource
provide a message digest over DNS zone data. In particular, it Record that can be used to provide an message digest over DNS zone
describes how to compute, sign, represent, and use the message digest data. The ZONEMD Resource Record conveys the message digest data in
to verify the contents of a zone for accuracy and completeness. The the zone itself. When a zone publisher includes an ZONEMD record,
ZONEMD Resource Record type is introduced for conveying the message recipients can verify the zone contents for accuracy and
digest data. completeness. This provides assurance that received zone data
matches published data, regardless of how the zone data has been
transmitted and received.
ZONEMD is not designed to replace DNSSEC. Whereas DNSSEC is designed
to protect recursive name servers and their caches, ZONEMD protects
applications that consume zone files, whether they be authoritative
name servers, recursive name servers, or uses of zone file data.
As specified at this time, ZONEMD is not designed for use in large,
dynamic zones due to the time and resources required for digest
calculation. The ZONEMD record described in this document includes
fields reserved for future work to support large, dynamic zones.
Status of This Memo Status of This Memo
This Internet-Draft is submitted in full conformance with the This Internet-Draft is submitted in full conformance with the
provisions of BCP 78 and BCP 79. provisions of BCP 78 and BCP 79.
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 January 3, 2019. This Internet-Draft will expire on April 12, 2019.
Copyright Notice Copyright Notice
Copyright (c) 2018 IETF Trust and the persons identified as the Copyright (c) 2018 IETF Trust and the persons identified as the
document authors. All rights reserved. document authors. All rights reserved.
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Table of Contents Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3
1.1. Motivation . . . . . . . . . . . . . . . . . . . . . . . 3 1.1. Motivation . . . . . . . . . . . . . . . . . . . . . . . 4
1.2. Design Overview . . . . . . . . . . . . . . . . . . . . . 5 1.2. Design Overview . . . . . . . . . . . . . . . . . . . . . 5
1.3. Requirements Language . . . . . . . . . . . . . . . . . . 6 1.3. Use Cases . . . . . . . . . . . . . . . . . . . . . . . . 6
2. The ZONEMD Resource Record . . . . . . . . . . . . . . . . . 6 1.3.1. Root Zone . . . . . . . . . . . . . . . . . . . . . . 6
2.1. ZONEMD RDATA Wire Format . . . . . . . . . . . . . . . . 6 1.3.2. Providers, Secondaries, and Anycast . . . . . . . . . 6
2.1.1. The Serial Field . . . . . . . . . . . . . . . . . . 6 1.3.3. Response Policy Zones . . . . . . . . . . . . . . . . 6
2.1.2. The Digest Type Field . . . . . . . . . . . . . . . . 6 1.3.4. Centralized Zone Data Service . . . . . . . . . . . . 7
2.1.3. The Digest Field . . . . . . . . . . . . . . . . . . 7 1.3.5. General Purpose Comparison Check . . . . . . . . . . 7
2.2. ZONEMD Presentation Format . . . . . . . . . . . . . . . 7 1.4. Requirements Language . . . . . . . . . . . . . . . . . . 7
2.3. ZONEMD Example . . . . . . . . . . . . . . . . . . . . . 7 2. The ZONEMD Resource Record . . . . . . . . . . . . . . . . . 7
3. Calculating the Digest . . . . . . . . . . . . . . . . . . . 8 2.1. ZONEMD RDATA Wire Format . . . . . . . . . . . . . . . . 7
3.1. Canonical Format and Ordering . . . . . . . . . . . . . . 8 2.1.1. The Serial Field . . . . . . . . . . . . . . . . . . 8
3.1.1. Order of RRsets Having the Same Owner Name . . . . . 8 2.1.2. The Digest Type Field . . . . . . . . . . . . . . . . 8
3.1.2. Special Considerations for SOA RRs . . . . . . . . . 8 2.1.3. The Reserved Field . . . . . . . . . . . . . . . . . 8
3.2. Add ZONEMD Placeholder . . . . . . . . . . . . . . . . . 8 2.1.4. The Digest Field . . . . . . . . . . . . . . . . . . 9
3.3. Optionally Sign the Zone . . . . . . . . . . . . . . . . 9 2.2. ZONEMD Presentation Format . . . . . . . . . . . . . . . 9
3.4. Calculate the Digest . . . . . . . . . . . . . . . . . . 9 2.3. ZONEMD Example . . . . . . . . . . . . . . . . . . . . . 9
3.4.1. Inclusion/Exclusion Rules . . . . . . . . . . . . . . 9 3. Calculating the Digest . . . . . . . . . . . . . . . . . . . 9
3.5. Update ZONEMD RR . . . . . . . . . . . . . . . . . . . . 10 3.1. Canonical Format and Ordering . . . . . . . . . . . . . . 9
4. Verifying Zone Message Digest . . . . . . . . . . . . . . . . 10 3.1.1. Order of RRsets Having the Same Owner Name . . . . . 10
5. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 11 3.1.2. Special Considerations for SOA RRs . . . . . . . . . 10
5.1. ZONEMD RRtype . . . . . . . . . . . . . . . . . . . . . . 11 3.2. Add ZONEMD Placeholder . . . . . . . . . . . . . . . . . 10
5.2. ZONEMD Digest Type . . . . . . . . . . . . . . . . . . . 11 3.3. Optionally Sign the Zone . . . . . . . . . . . . . . . . 10
6. Security Considerations . . . . . . . . . . . . . . . . . . . 11 3.4. Calculate the Digest . . . . . . . . . . . . . . . . . . 11
6.1. Attacks Against the Zone Digest . . . . . . . . . . . . . 11 3.4.1. Inclusion/Exclusion Rules . . . . . . . . . . . . . . 11
6.2. Attacks Utilizing the Zone Digest . . . . . . . . . . . . 12
7. Privacy Considerations . . . . . . . . . . . . . . . . . . . 12 3.5. Update ZONEMD RR . . . . . . . . . . . . . . . . . . . . 11
8. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 12 4. Verifying Zone Message Digest . . . . . . . . . . . . . . . . 12
9. Implementation Status . . . . . . . . . . . . . . . . . . . . 12 5. Scope of Experimentation . . . . . . . . . . . . . . . . . . 13
9.1. Authors' Implementation . . . . . . . . . . . . . . . . . 12 6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 13
10. Change Log . . . . . . . . . . . . . . . . . . . . . . . . . 13 6.1. ZONEMD RRtype . . . . . . . . . . . . . . . . . . . . . . 13
11. References . . . . . . . . . . . . . . . . . . . . . . . . . 13 6.2. ZONEMD Digest Type . . . . . . . . . . . . . . . . . . . 13
11.1. Normative References . . . . . . . . . . . . . . . . . . 13 7. Security Considerations . . . . . . . . . . . . . . . . . . . 13
11.2. Informative References . . . . . . . . . . . . . . . . . 14 7.1. Attacks Against the Zone Digest . . . . . . . . . . . . . 13
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 16 7.2. Attacks Utilizing the Zone Digest . . . . . . . . . . . . 14
8. Privacy Considerations . . . . . . . . . . . . . . . . . . . 14
9. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 14
10. Implementation Status . . . . . . . . . . . . . . . . . . . . 14
10.1. Authors' Implementation . . . . . . . . . . . . . . . . 14
10.2. Shane Kerr's Implementation . . . . . . . . . . . . . . 15
11. Change Log . . . . . . . . . . . . . . . . . . . . . . . . . 15
12. References . . . . . . . . . . . . . . . . . . . . . . . . . 17
12.1. Normative References . . . . . . . . . . . . . . . . . . 17
12.2. Informative References . . . . . . . . . . . . . . . . . 18
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 20
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 ([RFC7719]), which can be records (RRs) sharing a common origin ([RFC7719]). Zones are often
distributed from primary to secondary name servers. Zones are often
stored as files on disk in the so-called master file format stored as files on disk in the so-called master file format
[RFC1034]. Sometimes zones are distributed outside of the DNS, with [RFC1034]. Zones are generally distributed between name servers
such protocols as FTP, HTTP, rsync, and so on. Currently there is no using the AXFR [RFC5936], and IXFR [RFC1995] protocols. Zone files
standard way to verify the authenticity of a stand-alone zone file. can also be distributed outside of the DNS, with such protocols as
FTP, HTTP, rsync, and even via email. Currently there is no standard
way to verify the authenticity of a stand-alone zone file.
This document introduces a new RR type that serves as a cryptographic This document introduces a new RR type that serves as a cryptographic
message digest of the data in a zone file. It allows a receiver of message digest of the data in a zone file. It allows a receiver of
the zone file to verify the zone file's authenticity, especially when the zone file to verify the zone file's authenticity, especially when
used in combination with DNSSEC. This technique makes the message used in combination with DNSSEC. This technique makes the message
digest a part of the zone file itself, allowing anything to verify digest a part of the zone file itself, allowing verification the zone
the zone file as a whole, no matter how it is transmitted. file as a whole, no matter how it is transmitted. Furthermore, the
digest is based on the wire format of zone data. Thus, it
independent of presentation format, such as changes in whitespace,
capitalization, and comments.
DNSSEC provides three strong security guarantees relevant to this DNSSEC provides three strong security guarantees relevant to this
protocol: 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.
This specification is OPTIONAL to implement by both publishers and This specification is OPTIONAL to implement by both publishers and
consumers of zone file data. consumers of zone file data.
1.1. Motivation 1.1. Motivation
The motivation and design of this protocol enhancement is tied to the The motivation for this protocol enhancement is the desire for the
DNS root zone [InterNIC]. The root zone is perhaps the most widely ability to verify the authenticity of a stand-alone zone file,
distributed DNS zone on the Internet, served by 930 separate regardless of how it is transmitted. A consumer of zone file data
instances [RootServers] at the time of this writing. Additionally, should be able to verify that the data is as-published by the zone
many organizations configure their own name servers to serve the root operator.
zone locally. Reasons for doing so include privacy and reduced
access time. [RFC7706] describes one, but not the only, way to do
this. As the root zone spreads beyond its traditional deployment
boundaries, the need for verification of the completeness of the zone
contents becomes increasingly important.
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 can the distribution channel. The DNS has a number of features that can
already be used for channel security. Perhaps the most widely used already be used for channel security. Perhaps the most widely used
is DNS transaction signatures (TSIG [RFC2845]). TSIG uses shared is DNS transaction signatures (TSIG [RFC2845]). TSIG uses shared
secret keys and a message digest to protect individual query and secret keys and a message digest to protect individual query and
response messages. It is generally used to authenticate and validate response messages. It is generally used to authenticate and validate
UPDATE [RFC2136], AXFR [RFC5936], and IXFR [RFC1995] messages. UPDATE [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
skipping to change at page 4, line 31 skipping to change at page 4, line 50
techniques are ephemeral and are not retained after the data transfer techniques are ephemeral and are not retained after the data transfer
is complete. They can ensure that the client receives the data from is complete. They can ensure that the client receives the data from
the expected server, and that the data sent by the server is not the expected server, and that the data sent by the server is not
modified during transmission. However, they do not guarantee that modified during transmission. However, they do not guarantee that
the server transmits the data as originally published, and do not the server transmits the data as originally published, and do not
provide any methods to verify data that is read after transmission is provide any methods to verify data that is read after transmission is
complete. For example, a name server loading saved zone data upon complete. For example, a name server loading saved zone data upon
restart cannot guarantee that the on-disk data has not been modified. restart cannot guarantee that the on-disk data has not been modified.
For these reasons, it is preferable to secure the data itself. For these reasons, it is preferable to secure the data itself.
DNSSEC provides certain data security guarantees. For zones that are Why not simply rely on DNSSEC, which provides certain data security
signed, a recipient can validate all of the signed RRsets. guarantees? Certainly for zones that are signed, a recipient could
Additionally, the denial-of-existence records can prove that RRsets validate all of the signed RRsets. Additionally, denial-of-existence
have not been added or removed. However, not all RRsets in a zone records can prove that RRsets have not been added or removed.
are signed. The design of DNSSEC stipulates that delegations (non- However, not all RRsets in a zone are signed. The design of DNSSEC
apex NS records) are not signed, and neither are any glue records. stipulates that delegations (non-apex NS records) are not signed, and
Thus, changes to delegation and glue records cannot be detected by neither are any glue records. Thus, changes to delegation and glue
DNSSEC alone. Furthermore, zones that employ NSEC3 with opt-out are records cannot be detected by DNSSEC alone. Furthermore, zones that
susceptible to the removal or addition of names between the signed employ NSEC3 with opt-out are susceptible to the removal or addition
nodes. of names between the signed nodes. Whereas DNSSEC is primarily
designed to protect consumers of DNS response messages, this protocol
is designed to protect consumers of zone files.
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 [RFC3851]. In fact, the such as OpenPGP [RFC4880] and S/MIME [RFC3851]. In fact, the
internic.net site publishes PGP signatures along side the root zone internic.net site publishes PGP signatures along side 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. That is, a zone file signed with OpenPGP or S/MIME no distributed. That is, a zone file signed with OpenPGP or S/MIME no
longer looks like a zone file and could not directly be loaded into a longer looks like a zone file and could not directly be loaded into a
name server. Once loaded the signature data is lost, so it does not name server. Once loaded the signature data is lost, so it does not
survive further propagation. survive further propagation.
It seems the desire for data security in DNS zones was envisioned as It seems the desire for data security in DNS zones was envisioned as
far back as 1997. [RFC2065] is an obsoleted specification of the far back as 1997. [RFC2065] is an obsoleted specification of the
first generation DNSSEC Security Extensions. It describes a zone first generation DNSSEC Security Extensions. It describes a zone
transfer signature, aka AXFR SIG, which is similar to the technique transfer signature, aka AXFR SIG, which is similar to the technique
proposed by this document. That is, it proposes ordering all RRsets proposed by this document. That is, it proposes ordering all
in a zone, hashing their signatures, and then signing the zone hash. (signed) RRsets in a zone, hashing their contents, and then signing
The AXFR SIG is described only for use during zone transfers. It did the zone hash. The AXFR SIG is described only for use during zone
not postulate the need to validate zone data distributed outside of transfers. It did not postulate the need to validate zone data
the DNS. Furthermore, its successor, [RFC2535], omits the AXFR SIG, distributed outside of the DNS. Furthermore, its successor,
while at the same time introducing an IXFR SIG. [RFC2535], omits the AXFR SIG, while at the same time introducing an
IXFR SIG.
1.2. Design Overview 1.2. Design Overview
This document introduces a new Resource Record type designed to This document introduces a new Resource Record type designed to
convey a message digest of the content of a zone file. The digest is convey a message digest of the content of a zone file. The digest is
calculated at the time of zone publication. Ideally the zone is calculated at the time of zone publication. Ideally the zone is
signed with DNSSEC to guarantee that any modifications of the digest signed with DNSSEC to guarantee that any modifications of the digest
can be detected. can be detected. The procedures for digest calculation and DNSSEC
signing are similar (i.e., both require the same ordering of RRs) and
can be done in parallel.
The zone digest is designed to be used on zones that are relatively The zone digest is designed to be used on zones that are relatively
stable and have infrequent updates. As currently specified, the stable and have infrequent updates. As currently specified, the
digest is re-calculated over the entire zone content each time. This digest is re-calculated over the entire zone content each time. This
specification does not provide an efficient mechanism for incremental specification does not provide an efficient mechanism for incremental
updates of zone data. The authors believe that the incremental updates of zone data. It does, however, reserve a field in the
updates represent significant complexity which could be a barrier to ZONEMD record for future work to support incremental zone digest
implementation at this time (see DNS Camel). Nothing in this algorithms (e.g. using Merkle trees).
specification prevents future work to support incremental zone digest
algorithms (e.g. using Merkle trees and a different RR type).
The cryptographic algorithms available for zone digest are exactly It is expected that verification of a zone digest would be
the same as for DS records. This avoids the need for a separate implemented in name server software. That is, a name server can
digest algorithm registry. Any updates to the DS algorithms verify the zone data it was given and refuse to serve a zone which
automatically updates the algorithm status for zone digests. 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.
It is expected that verification of a zone digest will be implemented 1.3. Use Cases
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
verification. For signed zones, the name server would need a trust
anchor for DNSSEC validation. For signed non-root zones, the name
server may need to send queries to validate a chain-of-trust. Digest
verification may also be performed externally.
1.3. Requirements Language 1.3.1. Root Zone
The root zone [InterNIC] is perhaps the most widely distributed DNS
zone on the Internet, served by 930 separate instances [RootServers]
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.
[RFC7706] describes one, but not the only, way to do this. As the
root zone spreads beyond its traditional deployment boundaries, the
need for verification of the completeness of the zone contents
becomes increasingly important.
1.3.2. 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,
they may not have anticipated the complexity of modern DNS service
provisioning which can include 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.
1.3.3. Response Policy Zones
DNS Response Policy Zones is "a method of expressing DNS response
policy information inside specially constructed DNS zones..." [RPZ].
A number of companies provide RPZ feeds, which can be consumed by
name server and firewall products. Since these are zone files, AXFR
is often, but not necessarily used for transmission. While RPZ zones
can certainly be signed with DNSSEC, the data is not queried
directly, and would not be subject to DNSSEC validation.
1.3.4. Centralized Zone Data Service
ICANN operates the Centralized Zone Data Service [CZDS], which is a
repository of top-level domain zone files. Users request access to
the system, and to individual zones, and are then able to download
zone data for certain uses. Adding a zone digest to these would
provide CZDS users with assurances that the data has not been
modified. Note that ZONEMD could be added to CZDS zone data
independently of the zone served by production name servers.
1.3.5. General Purpose Comparison Check
Since the zone digest 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.
1.4. Requirements Language
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.
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
skipping to change at page 6, line 35 skipping to change at page 8, line 10
2.1. ZONEMD RDATA Wire Format 2.1. ZONEMD RDATA Wire Format
The ZONEMD RDATA wire format is encoded as follows: The 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 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 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 | | Serial |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Digest Type | | | Digest Type | Reserved | |
+-+-+-+-+-+-+-+-+ Digest + +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |
| Digest |
/ / / /
/ / / /
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
2.1.1. The Serial Field 2.1.1. The Serial Field
The Serial field is a 32-bit unsigned integer in network order. It The Serial field is a 32-bit unsigned integer in network order. It
is equal to the serial number from the zone's SOA record ([RFC1035] is equal to the serial number from the zone's SOA record ([RFC1035]
section 3.3.13) for which the message digest was generated. section 3.3.13) for which the message digest was generated.
2.1.2. The Digest Type Field 2.1.2. The Digest Type Field
The Digest Type field is an 8-bit unsigned integer, with meaning The Digest Type field is an 8-bit unsigned integer, with meaning
equivalent to the Digest Type of the DS resource record, as defined equivalent to the Digest Type of the DS resource record, as defined
in section 5.1.3 of [RFC4034]. in section 5.1.3 of [RFC4034] and values found in the IANA protocol
registry for DS digest types [iana-ds-digest-types].
The status of ZONEMD digest types (e.g., mandatory, optional, The status of ZONEMD digest types (e.g., mandatory, optional,
deprecated) SHALL always match the status for DS records. This deprecated), however, are independent of those for DS digest types.
information can be found in the IANA protocol registry for DS digest
types [iana-ds-digest-types].
At the time of this writing the following digest types are defined: At the time of this writing the following digest types are defined:
+-------+-----------------+-----------+-----------+ +-------+-----------------+------------+-----------+
| Value | Description | Status | Reference | | Value | Description | Status | Reference |
+-------+-----------------+-----------+-----------+ +-------+-----------------+------------+-----------+
| 1 | SHA1 | Mandatory | [RFC3658] | | 1 | SHA1 | Deprecated | [RFC3658] |
| 2 | SHA256 | Mandatory | [RFC4509] | | 2 | SHA256 | Mandatory | [RFC4509] |
| 3 | GOST R 34.11-94 | Optional | [RFC5933] | | 3 | GOST R 34.11-94 | Deprecated | [RFC5933] |
| 4 | SHA384 | Optional | [RFC6605] | | 4 | SHA384 | Optional | [RFC6605] |
+-------+-----------------+-----------+-----------+ +-------+-----------------+------------+-----------+
Table 1: Digest Types Table 1: ZONEMD Digest Types
2.1.3. The Digest Field 2.1.3. The Reserved Field
The Reserved field is an 8-bit unsigned integer, which is always set
to zero. This field is reserved for future work to support efficient
incremental updates.
2.1.4. The Digest Field
The Digest field is a variable-length sequence of octets containing The Digest field is a variable-length sequence of octets containing
the message digest. Section 3 describes how to calculate the digest the message digest. Section 3 describes how to calculate the digest
for a zone. Section 4 describes how to use the digest to verify the for a zone. Section 4 describes how to use the digest to verify the
contents of a zone. contents of a zone.
2.2. ZONEMD Presentation Format 2.2. ZONEMD Presentation Format
The presentation format of the RDATA portion is as follows: The presentation format of the RDATA portion is as follows:
The Serial field MUST be represented as an unsigned decimal integer. The Serial field MUST be represented as an unsigned decimal integer.
The Reserved field MUST be represented as an unsigned decimal integer
set to zero.
The Digest Type field MUST be represented as an unsigned decimal The Digest Type field MUST be represented as an unsigned decimal
integer. integer.
The Digest MUST be represented as a sequence of case-insensitive The Digest MUST be represented as a sequence of case-insensitive
hexadecimal digits. Whitespace is allowed within the hexadecimal hexadecimal digits. Whitespace is allowed within the hexadecimal
text. text.
2.3. ZONEMD Example 2.3. ZONEMD Example
The following example shows a ZONEMD RR. The following example shows a ZONEMD RR.
example.com. 86400 IN ZONEMD ( 2018031500 4 FEBE3D4CE2EC2FFA4BA9 example.com. 86400 IN ZONEMD ( 2018031500 4 0 FEBE3D4CE2EC2FFA4BA9
9D46CD69D6D29711E552 9D46CD69D6D29711E552
17057BEE7EB1A7B641A4 17057BEE7EB1A7B641A4
7BA7FED2DD5B97AE499F 7BA7FED2DD5B97AE499F
AFA4F22C6BD647DE ) AFA4F22C6BD647DE )
3. Calculating the Digest 3. Calculating the Digest
3.1. Canonical Format and Ordering 3.1. Canonical Format and Ordering
Calculation of the zone digest REQUIRES the RRs in a zone to be in a Calculation of the zone digest REQUIRES the RRs in a zone to be
consistent format and ordering. Correct ordering of the zone depends processed in a consistent format and ordering. Correct ordering of
on (1) ordering of owner names in the zone, (2) ordering of RRsets the zone depends on (1) ordering of owner names in the zone, (2)
with the same owner name, and (3) ordering of RRs within an RRset. ordering of RRsets with the same owner name, and (3) ordering of RRs
within an RRset.
This specification adopts DNSSEC's canonical ordering for names This specification adopts DNSSEC's canonical ordering for names
(Section 6.1 of [RFC4034]), and canonical ordering for RRs within an (Section 6.1 of [RFC4034]), and canonical ordering for RRs within an
RRset (Section 6.3 of [RFC4034]). It also adopts DNSSEC's canonical RRset (Section 6.3 of [RFC4034]). It also adopts DNSSEC's canonical
RR form (Section 6.2 of [RFC4034]). However, since DNSSEC does not RR form (Section 6.2 of [RFC4034]). However, since DNSSEC does not
define a canonical ordering for RRsets having the same owner name, define a canonical ordering for RRsets having the same owner name,
that ordering is defined here. that ordering is defined here.
3.1.1. Order of RRsets Having the Same Owner Name 3.1.1. Order of RRsets Having the Same Owner Name
skipping to change at page 8, line 44 skipping to change at page 10, line 30
Additionally, per established practices, the SOA record is generally Additionally, per established practices, the SOA record is generally
the first record in a zone file. However, according to the the first record in a zone file. However, according to the
requirement to sort RRsets with the same owner name by type, the SOA requirement to sort RRsets with the same owner name by type, the SOA
RR (type value 6) will not be first in the digest calculation. The RR (type value 6) will not be first in the digest calculation. The
zone's NS RRset (type value 2) at the apex MUST be processed before zone's NS RRset (type value 2) at the apex MUST be processed before
the SOA RR. the SOA RR.
3.2. Add ZONEMD Placeholder 3.2. Add ZONEMD Placeholder
In preparation for calculating the zone digest, any existing ZONEMD In preparation for calculating the zone digest, any existing ZONEMD
records MUST first be deleted from the zone. record MUST first be deleted from the zone.
Prior to calculation of the digest, and prior to signing with DNSSEC, Prior to calculation of the digest, and prior to signing with DNSSEC,
a placeholder ZONEMD record MUST be added to the zone. This serves a placeholder ZONEMD record MUST be added to the zone. This serves
two purposes: (1) it allows the digest to cover the Serial and Digest two purposes: (1) it allows the digest to cover the Serial, Reserved,
Type field values, and (2) ensures that appropriate denial-of- and Digest Type field values, and (2) ensures that appropriate
existence (NSEC, NSEC3) records are created if the zone is signed denial-of-existence (NSEC, NSEC3) records are created if the zone is
with DNSSEC. signed with DNSSEC.
It is RECOMMENDED that the TTL of the ZONEMD record match the TTL of
the SOA.
In the placeholder record, the Serial field MUST be set to the In the placeholder record, the Serial field MUST be set to the
current SOA Serial. The Digest Type field MUST be set to the value current SOA Serial. The Digest Type field MUST be set to the value
for the chosen digest algorithm. The Digest field MUST be set to all for the chosen digest algorithm. The Digest field MUST be set to all
zeroes and of length appropriate for the chosen digest algorithm. zeroes and of length appropriate for the chosen digest algorithm.
3.3. Optionally Sign the Zone 3.3. Optionally Sign the Zone
Following addition of the placeholder record, the zone MAY be signed Following addition of the placeholder record, the zone MAY be signed
with DNSSEC. Note that when the digest calculation is complete, and with DNSSEC. Note that when the digest calculation is complete, and
the ZONEMD record is updated, the signature(s) for that record MUST the ZONEMD record is updated, the signature(s) for that record MUST
be recalculated and updated as well. Therefore, the signer is not be recalculated and updated as well. Therefore, the signer is not
required to calculate a signature over the placeholder record at this required to calculate a signature over the placeholder record at this
step in the process, but it is harmless to do so. step in the process, but it is harmless to do so.
3.4. Calculate the Digest 3.4. Calculate the Digest
The zone digest is calculated by concatenating the canonical on-the- The zone digest is calculated by concatenating the canonical on-the-
wire form of all RRs in the zone, in the order described above, wire form (without name compression) of all RRs in the zone, in the
subject to the inclusion/exclusion rules described below, and then order described above, subject to the inclusion/exclusion rules
applying the digest algorithm: described below, and then applying the digest algorithm:
digest = digest_algorithm( RR(1) | RR(2) | RR(3) | ... ) digest = digest_algorithm( RR(1) | RR(2) | RR(3) | ... )
where "|" denotes concatenation, and where "|" denotes concatenation, and
RR(i) = owner | type | class | TTL | RDATA length | RDATA RR(i) = owner | type | class | TTL | RDATA length | RDATA
3.4.1. Inclusion/Exclusion Rules 3.4.1. Inclusion/Exclusion Rules
When calculating the digest, the following inclusion/exclusion rules When calculating the digest, the following inclusion/exclusion rules
skipping to change at page 9, line 49 skipping to change at page 11, line 38
o More than one SOA MUST NOT be included. o More than one SOA MUST NOT be included.
o The placeholder ZONEMD RR MUST be included. o The placeholder ZONEMD RR MUST 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:
o The RRSIG covering ZONEMD MUST NOT be included. o The RRSIG covering ZONEMD MUST NOT be included.
FOR DISCUSSION: Ambiguities about records that are in/out of zone. FOR DISCUSSION: Ambiguities about records that are in/out of zone.
For example, see Jinmei message to dnsop 2018-06-01 and followups. For example, see Jinmei message to dnsop 2018-06-01 and followups.
BIND will load and axfr data "occluded" by DNAME/NS. BIND will load and AXFR data "occluded" by DNAME/NS.
3.5. Update ZONEMD RR 3.5. Update ZONEMD RR
Once the zone digest has been calculated, its value is then copied to Once the zone digest has been calculated, its value is then copied to
the Digest field of the ZONEMD record. the Digest field of the ZONEMD record.
If the zone is signed with DNSSEC, the appropriate RRSIG records If the zone is signed with DNSSEC, the appropriate RRSIG records
covering the ZONEMD record MUST then be added. Because the ZONEMD covering the ZONEMD record MUST then be added or updated. Because
placeholder was added prior to signing, the zone will already have the ZONEMD placeholder was added prior to signing, the zone will
the appropriate denial-of-existence (NSEC, NSEC3) records. already have the appropriate denial-of-existence (NSEC, NSEC3)
records.
Some implementations of incremental DNSSEC signing might update the Some implementations of incremental DNSSEC signing might update the
zone's serial number for each resigning. However, to preserve the zone's serial number for each resigning. However, to preserve the
calculated digest, generation of the ZONEMD signature at this time calculated digest, generation of the ZONEMD signature at this time
MUST NOT also result in a change of the SOA serial number. MUST NOT also result in a change of the SOA serial number.
4. Verifying Zone Message Digest 4. Verifying Zone Message Digest
The recipient of a zone that has a message digest record can verify The recipient of a zone that has a message digest record can verify
the zone by calculating the digest as follows: the zone by calculating the digest as follows:
skipping to change at page 10, line 42 skipping to change at page 12, line 32
record MUST be verified. If the ZONEMD record provably does not record MUST be verified. If the ZONEMD record provably does not
exist, digest verification cannot be done. If the ZONEMD record exist, digest verification cannot be done. If the ZONEMD record
does provably exist, but is not found in the zone, digest 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 signed, the SOA RR and ZONEMD RR(set) 3. For zones that are provably signed, the SOA RR and ZONEMD RR(set)
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
verification MUST NOT be considered successful. verification MUST NOT be considered successful.
4. The SOA Serial field MUST exactly match the ZONEMD Serial field. 4. If the zone contains more than one ZONEMD RR, digest verification
MUST NOT be considered successful.
5. The SOA Serial field MUST exactly match the ZONEMD Serial field.
If the fields to not match, digest verification MUST NOT be If the fields to not match, digest verification MUST NOT be
considered successful. considered successful.
5. The ZONEMD Digest Type field MUST be checked. If the verifier 6. The ZONEMD Digest Type field MUST be checked. If the verifier
does not support the given digest type, it SHOULD report that the does not support the given digest type, it SHOULD report that the
zone digest could not be verified due to an unsupported zone digest could not be verified due to an unsupported
algorithm. algorithm.
6. The zone digest is calculated using the algorithm described in 7. The zone digest is calculated using the algorithm described in
Section 3.4. Note in particular that digested ZONEMD RRs MUST be Section 3.4. Note in particular that the digested ZONEMD RR MUST
placeholders and their RRSIGs are not included in the digest. be a placeholder and its RRSIGs MUST NOT be included in the
digest.
7. The calculated digest is compared to the received digest. If the 8. The calculated digest is compared to the received digest. If the
two digest values match, verification is considered successful. two digest values match, verification is considered successful.
Otherwise, verification MUST NOT be considered successful. Otherwise, verification MUST NOT be considered successful.
8. If the zone is to be served and transferred, the original (not 9. If the zone is to be served and transferred, the original (not
placeholder) ZONEMD RRs MUST be sent to recipients so that placeholder) ZONEMD RR MUST be sent to recipients so that
downstream clients can verify the zone. downstream clients can verify the zone.
5. IANA Considerations 5. Scope of Experimentation
5.1. ZONEMD RRtype This memo is published as an Experimental RFC. The purpose of the
experimental period is to provide the community time to analyze and
evaluate to the methods defined in this document, particularly with
regard to the wide variety of DNS zones in use on the Internet.
Additionally, the ZONEMD record defined in this document includes a
Reserved field. The authors have a particular future use in mind for
this field, namely to support efficient digests in large, dynamic
zones. We intend to conduct future experiments using Merkle trees of
varying depth. The choice of tree depth can be encoded in this
reserved field.
The duration of the experiment is expected to be no less than two
years from the publication of this document. If the experiment is
successful, it is expected that the findings of the experiment will
result in an updated document for Standards Track approval.
6. IANA Considerations
6.1. ZONEMD RRtype
This document uses a new DNS RR type, ZONEMD, whose value TBD has This document uses a new DNS RR type, ZONEMD, whose value TBD 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.
5.2. ZONEMD Digest Type 6.2. ZONEMD Digest Type
The ZONEMD Digest Type field has the same semantics as the DS RR The ZONEMD Digest Type field has the same values as the DS RR Digest
Digest Type field. Thus, it does not add new IANA protocol registry Type field, but with independent implementation status. Therefore,
requirements. this document expects IANA will create a new "ZONEMD Digest Types"
registry.
6. Security Considerations 7. Security Considerations
6.1. Attacks Against the Zone Digest 7.1. Attacks Against the Zone Digest
The zone digest allows the receiver to verify that the zone contents The zone digest allows the receiver to verify that the zone contents
haven't been modified since the zone was generated/published. haven't been modified since the zone was generated/published.
Verification is strongest when the zone is also signed with DNSSEC. Verification is strongest when the zone is also signed with DNSSEC.
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 RECOMMENDS that the verifier determine whether This is why Section 4 RECOMMENDS that the verifier determine whether
or not to expect DNSSEC signatures for the zone in step 1. or not to expect DNSSEC signatures for the zone in step 1.
The attacker might perform a downgrade attack by removing the ZONEMD The attacker might perform a downgrade attack by removing the ZONEMD
record. This is why Section 4 REQUIRES that the verifier checks record. This is why Section 4 REQUIRES that the verifier checks
DNSSEC denial-of-existence proofs in step 2. DNSSEC denial-of-existence proofs in step 2.
The attacker might alter the Digest Type or Digest fields of the The attacker might alter the Digest Type or Digest fields of the
ZONEMD record. Such modifications are detectable only with DNSSEC ZONEMD record. Such modifications are detectable only with DNSSEC
validation. validation.
6.2. Attacks Utilizing the Zone Digest 7.2. Attacks Utilizing the Zone Digest
Nothing in this specification prevents clients from making, and Nothing in this specification prevents clients from making, and
servers from responding to, ZONEMD queries. One might consider how servers from responding to, ZONEMD queries. One might consider how
well ZONEMD responses could be used in a distributed denial-of- well ZONEMD responses could be used in a distributed denial-of-
service amplification attack. service amplification attack.
The ZONEMD RR is moderately sized, much like the DS RR. A single The ZONEMD RR is moderately sized, much like the DS RR. A single
ZONEMD RR contributes approximately 40 to 65 octets to a DNS ZONEMD RR contributes approximately 40 to 65 octets to a DNS
response, for currently defined digest types. Certainly other query response, for currently defined digest types. Certainly other query
types result in larger amplification effects (i.e., DNSKEY). types result in larger amplification effects (i.e., DNSKEY).
FOR DISCUSSION: The primary purpose of the ZONEMD record is to verify 8. Privacy Considerations
a zone file prior to being loaded or served by a name server. We
could allow a name server implementation to respond to ZONEMD queries
with the REFUSED RCODE without loss of functionality. Note that
refusal would prevent ensuring that a zone-walk is complete.
7. Privacy Considerations
This specification has no impacts on user privacy. This specification has no impacts on user privacy.
8. 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 Mark Andrews, Olafur Gudmundsson, Shumon Additionally, they thank Joe Abley, Mark Andrews, Olafur Gudmundsson,
Huque, Tatuya Jinmei, Shane Kerr, Mukund Sivaraman, Petr Spacek, and Paul Hoffman, Evan Hunt, Shumon Huque, Tatuya Jinmei, Burt Kaliski,
other members of the dnsop working group for their input. Shane Kerr, Matt Larson, John Levine, Ed Lewis, Mukund Sivaraman,
Petr Spacek, Ondrej Sury, Florian Weimer, Tim Wicinksi, Paul Wouters,
and other members of the dnsop working group for their input.
9. Implementation Status 10. Implementation Status
9.1. Authors' Implementation 10.1. Authors' Implementation
The authors are currently working on an implementation in C, using The authors have an open source implementation in C, using the ldns
the ldns library [ldns]. This implementation is able to perform the library [ldns-zone-digest]. This implementation is able to perform
following functions: the following functions:
o Read input zone file, output zone file with ZONEMD placeholder. o Read an input zone file and output a zone file with the ZONEMD
placeholder.
o Compute zone digest over signed zone file and update ZONEMD o Compute zone digest over signed zone file and update the ZONEMD
record. record.
o Re-compute DNSSEC signature over ZONEMD record. o Re-compute DNSSEC signature over the ZONEMD record.
o Verify zone digest from input zone file. o Verify the zone digest from an input zone file.
The authors expect to be able to release this implementation as open This implementation does not:
source following submission of this Internet-Draft.
10. Change Log o Perform DNSSEC validation of the ZONEMD record.
o Support the Gost digest algorithm.
o Output the ZONEMD record in its defined presentation format.
10.2. Shane Kerr's Implementation
Shane Kerr wrote an implementation of this specification during the
IETF 102 hackathon [ZoneDigestHackathon]. This implementation is in
Python and is able to perform the following functions:
o Read an input zone file and a output zone file with ZONEMD record.
o Verify the zone digest from an input zone file.
o Output the ZONEMD record in its defined presentation format.
o Generate Gost digests.
This implementation does not:
o Re-compute DNSSEC signature over the ZONEMD record.
o Perform DNSSEC validation of the ZONEMD record.
11. Change Log
RFC Editor: Please remove this section. RFC Editor: Please remove this section.
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:
o Removed requirement to sort by RR CLASS. o Removed requirement to sort by RR CLASS.
o Added Kumari and Hardaker as coauthors. o Added Kumari and Hardaker as coauthors.
o Added Change Log section. o Added Change Log section.
o Minor clarifications and grammatical edits. o Minor clarifications and grammatical edits.
11. References From -01 to -02:
11.1. Normative References o Emphasize desire for data security over channel security.
o Expanded motivation into its own subsection.
o Removed discussion topic whether or not to include serial in
ZONEMD.
o Clarified that a zone's NS records always sort before the SOA
record.
o Clarified that all records in the zone must are digested, except
as specified in the exclusion rules.
o Added for discussion out-of-zone and occluded records.
o Clarified that update of ZONEMD signature must not cause a serial
number change.
o Added persons to acknowledgments.
From -02 to -03:
o Added recommendation to set ZONEMD TTL to SOA TTL.
o Clarified that digest input uses uncompressed names.
o Updated Implementations section.
o Changed intended status from Standards Track to Experimental and
added Scope of Experiment section.
o Updated Motivation, Introduction, and Design Overview sections in
response to working group discussion.
o Gave ZONEMD digest types their own status, separate from DS digest
types. Request IANA to create a registry.
o Added Reserved field for future work supporting dynamic updates.
o Be more rigorous about having just ONE ZONEMD record in the zone.
o Expanded use cases.
12. References
12.1. Normative References
[iana-ds-digest-types] [iana-ds-digest-types]
IANA, "Delegation Signer (DS) Resource Record (RR) Type IANA, "Delegation Signer (DS) Resource Record (RR) Type
Digest Algorithms", April 2012, Digest Algorithms", April 2012,
<https://www.iana.org/assignments/ds-rr-types/ <https://www.iana.org/assignments/ds-rr-types/
ds-rr-types.xhtml>. ds-rr-types.xhtml>.
[ldns] NLNet Labs, "The ldns Library", March 2018,
<https://www.nlnetlabs.nl/projects/ldns/>.
[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,
November 1987, <https://www.rfc-editor.org/info/rfc1035>. November 1987, <https://www.rfc-editor.org/info/rfc1035>.
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, Requirement Levels", BCP 14, RFC 2119,
skipping to change at page 14, line 33 skipping to change at page 18, line 9
[RFC6605] Hoffman, P. and W. Wijngaards, "Elliptic Curve Digital [RFC6605] Hoffman, P. and W. Wijngaards, "Elliptic Curve Digital
Signature Algorithm (DSA) for DNSSEC", RFC 6605, Signature Algorithm (DSA) for DNSSEC", RFC 6605,
DOI 10.17487/RFC6605, April 2012, DOI 10.17487/RFC6605, April 2012,
<https://www.rfc-editor.org/info/rfc6605>. <https://www.rfc-editor.org/info/rfc6605>.
[RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC [RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC
2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174, 2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174,
May 2017, <https://www.rfc-editor.org/info/rfc8174>. May 2017, <https://www.rfc-editor.org/info/rfc8174>.
11.2. Informative References 12.2. Informative References
[CZDS] Internet Corporation for Assigned Names and Numbers,
"Centralized Zone Data Service", October 2018,
<https://czds.icann.org/>.
[dns-over-https] [dns-over-https]
Hoffman, P. and P. McManus, "DNS Queries over HTTPS Hoffman, P. and P. McManus, "DNS Queries over HTTPS
(DoH)", draft-ietf-doh-dns-over-https-12 (work in (DoH)", draft-ietf-doh-dns-over-https-12 (work in
progress), June 2018, <https://tools.ietf.org/html/ progress), June 2018, <https://tools.ietf.org/html/
draft-ietf-doh-dns-over-https-12>. draft-ietf-doh-dns-over-https-12>.
[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]
Verisign, "Implementation of Message Digests for DNS Zones
using the ldns library", July 2018,
<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,
DOI 10.17487/RFC1995, August 1996, DOI 10.17487/RFC1995, August 1996,
<https://www.rfc-editor.org/info/rfc1995>. <https://www.rfc-editor.org/info/rfc1995>.
[RFC2065] Eastlake 3rd, D. and C. Kaufman, "Domain Name System [RFC2065] Eastlake 3rd, D. and C. Kaufman, "Domain Name System
Security Extensions", RFC 2065, DOI 10.17487/RFC2065, Security Extensions", RFC 2065, DOI 10.17487/RFC2065,
January 1997, <https://www.rfc-editor.org/info/rfc2065>. January 1997, <https://www.rfc-editor.org/info/rfc2065>.
[RFC2136] Vixie, P., Ed., Thomson, S., Rekhter, Y., and J. Bound, [RFC2136] Vixie, P., Ed., Thomson, S., Rekhter, Y., and J. Bound,
"Dynamic Updates in the Domain Name System (DNS UPDATE)", "Dynamic Updates in the Domain Name System (DNS UPDATE)",
skipping to change at page 16, line 9 skipping to change at page 19, line 41
[RFC7858] Hu, Z., Zhu, L., Heidemann, J., Mankin, A., Wessels, D., [RFC7858] Hu, Z., Zhu, L., Heidemann, J., Mankin, A., Wessels, D.,
and P. Hoffman, "Specification for DNS over Transport and P. Hoffman, "Specification for DNS over Transport
Layer Security (TLS)", RFC 7858, DOI 10.17487/RFC7858, May Layer Security (TLS)", RFC 7858, DOI 10.17487/RFC7858, May
2016, <https://www.rfc-editor.org/info/rfc7858>. 2016, <https://www.rfc-editor.org/info/rfc7858>.
[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)", draft-vixie-dnsop-dns-rpz-00 (work in progress),
June 2018, <https://tools.ietf.org/html/
draft-vixie-dnsop-dns-rpz-00>.
[ZoneDigestHackathon]
Kerr, S., "Prototype implementation of ZONEMD for the IETF
102 hackathon in Python", July 2018,
<https://github.com/shane-kerr/ZoneDigestHackathon>.
Authors' Addresses Authors' Addresses
Duane Wessels Duane Wessels
Verisign Verisign
12061 Bluemont Way 12061 Bluemont Way
Reston, VA 20190 Reston, VA 20190
Phone: +1 703 948-3200 Phone: +1 703 948-3200
Email: dwessels@verisign.com Email: dwessels@verisign.com
URI: http://verisign.com URI: http://verisign.com
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