Network Working Group J. Abley
Internet-Draft ICANN
Intended status: Informational J. Schlyter
Expires: April 22, 2011 Kirei
October 19, 2010
DNSSEC Trust Anchor Publication for the Root Zone
draft-jabley-dnssec-trust-anchor-01
Abstract
The root zone of the Domain Name System (DNS) has been
cryptographically signed using DNS Security Extensions (DNSSEC).
In order to obtain secure answers from the root zone of the DNS using
DNSSEC, a client must configure a suitable trust anchor. This
document describes how such trust anchors are published.
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3
2. Root Zone Trust Anchor Publication . . . . . . . . . . . . . . 4
2.1. XML . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
2.2. Certificate Signing Request (PKCS#10) . . . . . . . . . . 4
3. Root Zone Trust Anchor Retrieval . . . . . . . . . . . . . . . 5
3.1. HTTP . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
3.2. HTTP Over TLS . . . . . . . . . . . . . . . . . . . . . . 5
3.3. Signature Verification . . . . . . . . . . . . . . . . . . 6
4. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 7
5. Security Considerations . . . . . . . . . . . . . . . . . . . 8
6. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 9
7. References . . . . . . . . . . . . . . . . . . . . . . . . . . 10
7.1. Normative References . . . . . . . . . . . . . . . . . . . 10
7.2. Informative References . . . . . . . . . . . . . . . . . . 11
Appendix A. Trust Anchor Publication Document Schema . . . . . . 12
Appendix B. Example Signed Trust Anchor Set . . . . . . . . . . . 13
Appendix C. ASN.1 Module for DNS Resource Record . . . . . . . . 14
Appendix D. Historical Note . . . . . . . . . . . . . . . . . . . 15
Appendix E. About this Document . . . . . . . . . . . . . . . . . 16
E.1. Discussion . . . . . . . . . . . . . . . . . . . . . . . . 16
E.2. Document History . . . . . . . . . . . . . . . . . . . . . 16
E.2.1. draft-jabley-dnssec-trust-anchor-00 . . . . . . . . . 16
E.2.2. draft-jabley-dnssec-trust-anchor-01 . . . . . . . . . 16
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 17
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1. Introduction
The Domain Name System (DNS) is described in [RFC1034] and [RFC1035].
Security extensions to the DNS (DNSSEC) are described in [RFC4033],
[RFC4034], [RFC4035], [RFC4509], [RFC5155] and [RFC5702].
A discussion of operational practices relating to DNSSEC can be found
in [RFC4641].
In DNSSEC resource record sets (RRSets) are cryptographically-signed,
such that a response to a query contains signatures which allow its
integrity and authenticity to be verified. An individual signature
is validated by following a chain of signatures to a key which is
trusted for some extra-protocol reason.
The publication of trust anchors for the root zone of the DNS is an
IANA function performed by ICANN. A detailed description of
corresponding key management practices can be found in [DPS], which
can be retrieved from the IANA Repository located at
<https://www.iana.org/dnssec/>.
This document describes the distribution of DNSSEC trust anchors.
Whilst the data formats and the publication and retrieval methods
described in this document might well be adapted for other uses, this
document's focus is more specific and is concerned only with the
distribution of trust anchors for the root zone.
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2. Root Zone Trust Anchor Publication
Trust anchors for the root zone are published in two formats, each of
which is described in this document:
o as the hashes of the corresponding DNSKEY records, consistent with
the defined presentation format of Delegation Signer (DS) resource
records [RFC4034], contained within an XML document, as described
in Section 2.1, and
o as Certificate Signing Requests (CSRs) in PKCS#10 format [RFC2986]
for further processing by Certification Authorities and validation
of proof of possession of the corresponding private keys, as
described in Section 2.2.
2.1. XML
Trust anchors are published in an XML document whose schema is
described in Appendix A. The document contains a complete set of
trust anchors for the root zone, including anchors suitable for
immediate use and also historical data.
Examples of trust anchors packaged and signed for publication can be
found in Appendix B.
2.2. Certificate Signing Request (PKCS#10)
To facilitate signing the trust anchor by a public key
infrastructure, trust anchors are also published as Certificate
Signing Requests (CSRs) in PKCS#10 format [RFC2986].
Each CSR will have a Subject with following attributes:
O: the string "ICANN".
OU: the string "IANA".
CN: the string "Root Zone KSK" followed by the time and date of key
generation in the format specified in [RFC3339], e.g. "Root Zone
KSK 2010-06-16T21:19:24+00:00".
resourceRecord: the hash of the public key consistent with the
presentation format of the Delegation Signer (DS) [RFC4034]
resource record (see Appendix C for attribute definition).
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3. Root Zone Trust Anchor Retrieval
3.1. HTTP
Trust anchors are available for retrieval using HTTP [RFC2616].
The URL for retrieving the CSR is
<http://data.iana.org/root-anchors/key-label.csr>, with "key-label"
replaced by the key label of the corresponding KSK.
The URL for retrieving the IANA-signed Certificate is
<http://data.iana.org/root-anchors/key-label.crt>, with "key-label"
again replaced as described above.
The URL for retrieving the complete trust anchor set is
<http://data.iana.org/root-anchors/root-anchors.xml>.
The URL for a detached S/MIME [RFC5751] signature for the current
trust anchor set is
<http://data.iana.org/root-anchors/root-anchors.p7s>.
The URL for a detached OpenPGP [RFC4880] signature for the current
trust anchor set is
<http://data.iana.org/root-anchors/root-anchors.asc>.
3.2. HTTP Over TLS
Trust anchors are available for retrieval using HTTP over TLS
[RFC2818].
The URLs specified in Section 3.1 are also available using HTTPS.
That is:
The URL for retrieving the CSR is
<https://data.iana.org/root-anchors/key-label.csr>, with "key-label"
replaced by the key label of the corresponding KSK.
The URL for retrieving the IANA-signed Certificate is
<https://data.iana.org/root-anchors/key-label.crt>, with "key-label"
again replaced as described above.
The URL for retrieving the complete trust anchor set is
<https://data.iana.org/root-anchors/root-anchors.xml>.
The URL for a detached S/MIME [RFC5751] signature for the current
trust anchor set is
<https://data.iana.org/root-anchors/root-anchors.p7s>.
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The URL for a detached OpenPGP [RFC4880] signature for the current
trust anchor set is
<https://data.iana.org/root-anchors/root-anchors.asc>.
TLS sessions are authenticated with certificates presented from the
server. No client certificate verification is performed. The
certificate presented by the server is chosen such that it can be
trusted using an X.509 trust anchor that is believed to be well-
known, e.g. one that corresponds to a WebTrust-accredited Certificate
Authority. Other TLS authentication mechanisms may be considered in
the future.
3.3. Signature Verification
The OpenPGP [RFC4880] keys used to sign trust anchor documents carry
signatures from personal keys of staff who are able to personally
attest to their validity. Those staff members will continue to make
their personal keys freely available for examination by third
parties, e.g. by way of PGP key parties at operator and IETF
meetings. In this fashion a diverse set of paths through the PGP web
of trust will be maintained to the trust anchor PGP keys.
An OpenPGP keyring containing public keys pertinent to signature
verification is published at
<http://data.iana.org/root-anchors/icann.pgp>. The public keys on
that keyring will also be distributed widely, e.g. to public PGP key
servers.
Certificates used to create S/MIME [RFC5751] signatures will be
signed by a Certificate Authority (CA) administered by ICANN as the
IANA functions operator and also optionally by well-known (e.g.
WebTrust-certified) CAs to facilitate signature validation with
widely-available X.509 trust anchors.
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4. IANA Considerations
Key Signing Key (KSK) management for the root zone is an IANA
function. This document describes an initial set of publication
mechanisms for trust anchors related to that management. In the
future, additional publication schemes may be also be made available,
in which case they will be described in a new document that updates
this one.
Existing mechanisms will not be deprecated without very strong
technical justification.
This document contains information about an existing service, and has
no IANA actions.
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5. Security Considerations
This document describes how DNSSEC trust anchors for the root zone of
the DNS are published. It is to be expected that many DNSSEC clients
will only configure a single trust anchor to perform validation, and
that the trust anchor they use will be that of the root zone. As a
consequence, reliable publication of trust anchors is important.
This document aims to specify carefully the means by which such trust
anchors are published, as an aid to the formats and retrieval methods
described here being integrated usefully into user environments.
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6. Acknowledgements
Many pioneers paved the way for the deployment of DNSSEC in the root
zone of the DNS, and the authors hereby acknowledge their substantial
collective contribution.
This document incorporates suggestions made by Paul Hoffman and
Alfred Hoenes, whose contributions are appreciated.
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7. References
7.1. Normative References
[RFC1034] Mockapetris, P., "Domain names - concepts and facilities",
STD 13, RFC 1034, November 1987.
[RFC1035] Mockapetris, P., "Domain names - implementation and
specification", STD 13, RFC 1035, November 1987.
[RFC2616] Fielding, R., Gettys, J., Mogul, J., Frystyk, H.,
Masinter, L., Leach, P., and T. Berners-Lee, "Hypertext
Transfer Protocol -- HTTP/1.1", RFC 2616, June 1999.
[RFC2818] Rescorla, E., "HTTP Over TLS", RFC 2818, May 2000.
[RFC2986] Nystrom, M. and B. Kaliski, "PKCS #10: Certification
Request Syntax Specification Version 1.7", RFC 2986,
November 2000.
[RFC3339] Klyne, G., Ed. and C. Newman, "Date and Time on the
Internet: Timestamps", RFC 3339, July 2002.
[RFC4033] Arends, R., Austein, R., Larson, M., Massey, D., and S.
Rose, "DNS Security Introduction and Requirements",
RFC 4033, March 2005.
[RFC4034] Arends, R., Austein, R., Larson, M., Massey, D., and S.
Rose, "Resource Records for the DNS Security Extensions",
RFC 4034, March 2005.
[RFC4035] Arends, R., Austein, R., Larson, M., Massey, D., and S.
Rose, "Protocol Modifications for the DNS Security
Extensions", RFC 4035, March 2005.
[RFC4509] Hardaker, W., "Use of SHA-256 in DNSSEC Delegation Signer
(DS) Resource Records (RRs)", RFC 4509, May 2006.
[RFC4641] Kolkman, O. and R. Gieben, "DNSSEC Operational Practices",
RFC 4641, September 2006.
[RFC4880] Callas, J., Donnerhacke, L., Finney, H., Shaw, D., and R.
Thayer, "OpenPGP Message Format", RFC 4880, November 2007.
[RFC5155] Laurie, B., Sisson, G., Arends, R., and D. Blacka, "DNS
Security (DNSSEC) Hashed Authenticated Denial of
Existence", RFC 5155, March 2008.
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[RFC5702] Jansen, J., "Use of SHA-2 Algorithms with RSA in DNSKEY
and RRSIG Resource Records for DNSSEC", RFC 5702,
October 2009.
[RFC5751] Ramsdell, B. and S. Turner, "Secure/Multipurpose Internet
Mail Extensions (S/MIME) Version 3.2 Message
Specification", RFC 5751, January 2010.
7.2. Informative References
[DPS] Ljunggren, F., Okubo, T., Lamb, R., and J. Schlyter,
"DNSSEC Practice Statement for the Root Zone KSK
Operator", May 2010.
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Appendix A. Trust Anchor Publication Document Schema
A Relax NG Compact Schema for the documents used to publish trust
anchors can be found in Figure 1.
datatypes xsd = "http://www.w3.org/2001/XMLSchema-datatypes"
start = element TrustAnchor {
attribute id { xsd:string },
attribute source { xsd:string },
element Zone { xsd:string },
keydigest+
}
keydigest = element KeyDigest {
attribute id { xsd:string },
attribute validFrom { xsd:dateTime },
attribute validUntil { xsd:dateTime }?,
element KeyTag {
xsd:nonNegativeInteger { maxInclusive = "65535" } },
element Algorithm {
xsd:nonNegativeInteger { maxInclusive = "255" } },
element DigestType {
xsd:nonNegativeInteger { maxInclusive = "255" } },
element Digest { xsd:hexBinary }
}
Figure 1
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Appendix B. Example Signed Trust Anchor Set
Figure 2 describes two trust anchors for the root zone such as might
be retrieved using the URL
<https://data.iana.org/root-anchors/root-anchors.xml>.
<?xml version="1.0" encoding="UTF-8"?>
<TrustAnchor
id="AD42165F-B099-4778-8F42-D34A1D41FD93"
source="http://data.iana.org/root-anchors/root-anchors.xml">
<Zone>.</Zone>
<KeyDigest id="42"
validFrom="2010-07-01T00:00:00-00:00"
validUntil="2010-08-01T00:00:00-00:00">
<KeyTag>34291</KeyTag>
<Algorithm>5</Algorithm>
<DigestType>1</DigestType>
<Digest>c8cb3d7fe518835490af8029c23efbce6b6ef3e2</Digest>
</KeyDigest>
<KeyDigest id="53"
validFrom="2010-08-01T00:00:00-00:00">
<KeyTag>12345</KeyTag>
<Algorithm>5</Algorithm>
<DigestType>1</DigestType>
<Digest>a3cf809dbdbc835716ba22bdc370d2efa50f21c7</Digest>
</KeyDigest>
</TrustAnchor>
Figure 2
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Appendix C. ASN.1 Module for DNS Resource Record
ResourceRecord
{ iso(1) identified-organization(3) dod(6) internet(1) security(5)
mechanisms(5) pkix(7) id-mod(0) id-mod-dns-resource-record(70) }
DEFINITIONS IMPLICIT TAGS ::=
BEGIN
-- EXPORTS ALL --
IMPORTS
caseIgnoreMatch FROM SelectedAttributeTypes
{ joint-iso-itu-t ds(5) module(1) selectedAttributeTypes(5) 4 }
;
iana OBJECT IDENTIFIER ::= { iso(1) identified-organization(3)
dod(6) internet(1) private(4) enterprise(1) 1000 }
iana-dns OBJECT IDENTIFIER ::= { iana 53 }
resourceRecord ATTRIBUTE ::= {
WITH SYNTAX IA5String
EQUALITY MATCHING RULE caseIgnoreIA5Match
ID iana-dns
}
END
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Appendix D. Historical Note
The first KSK for use in the root zone of the DNS was generated at a
key ceremony at an ICANN Key Management Facility (KMF) in Culpeper,
Virginia, USA on 2010-06-16. This key entered production during a
second key ceremony held at an ICANN KMF in El Segundo, California,
USA on 2010-07-12. The resulting trust anchor was first published on
2010-07-15.
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Appendix E. About this Document
[RFC Editor: please remove this section, including all subsections,
prior to publication.]
E.1. Discussion
This document is not the product of any IETF working group. However,
communities interested in similar technical work can be found at the
IETF in the DNSOP and DNSEXT working groups.
The team responsible for deployment of DNSSEC in the root zone can be
reached at rootsign@icann.org.
The authors also welcome feedback sent to them directly.
E.2. Document History
E.2.1. draft-jabley-dnssec-trust-anchor-00
This document is based on earlier documentation used within and
published by the team responsible for DNSSEC deployment in the root
zone. This is the first revision circulated with the intention of
publication in the RFC series.
E.2.2. draft-jabley-dnssec-trust-anchor-01
Incorporated initial community suggestions. Editorial improvements.
Allocate OID and clean up syntax of ASN.1 module.
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Authors' Addresses
Joe Abley
ICANN
4676 Admiralty Way, Suite 330
Marina del Rey, CA 90292
US
Phone: +1 519 670 9327
Email: joe.abley@icann.org
Jakob Schlyter
Kirei AB
P.O. Box 53204
Goteborg SE-400 16
Sweden
Email: jakob@kirei.se
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