Network Working Group                                           J. Abley
Internet-Draft                                                     ICANN
Intended status: Informational                               J. Schlyter
Expires: October 27, 2011                                          Kirei
                                                          April 25, 2011


           DNSSEC Trust Anchor Publication for the Root Zone
                  draft-jabley-dnssec-trust-anchor-03

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.

Status of this Memo

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   provisions of BCP 78 and BCP 79.

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   This Internet-Draft will expire on October 27, 2011.

Copyright Notice

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   document authors.  All rights reserved.

   This document is subject to BCP 78 and the IETF Trust's Legal
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   include Simplified BSD License text as described in Section 4.e of



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   the Trust Legal Provisions and are provided without warranty as
   described in the Simplified BSD License.


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
       E.2.3.  draft-jabley-dnssec-trust-anchor-02  . . . . . . . . . 16
       E.2.4.  draft-jabley-dnssec-trust-anchor-03  . . . . . . . . . 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.  Each trust anchor optionally
   includes Uniform Resource Locators (URLs) for retrieving
   corresponding X.509 certificates.

   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 },

       element Certificate {
               attribute source { xsd:string },
               empty
       }+
   }


                                 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>
           <Certificate
             source="http://data.iana.org/root-anchors/Kexample1.crt"/>
           <Certificate
             source="http://data.iana.org/root-anchors/Kexample2.crt"/>
       </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.

E.2.3.  draft-jabley-dnssec-trust-anchor-02

   Draft expired.

E.2.4.  draft-jabley-dnssec-trust-anchor-03

   Added the optional <Certificate> element to the XML schema to provide
   a mechanism for locating external X.509 certificates relating to a
   particular key.












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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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