Use of SHA-2 Algorithms with RSA in DNSKEY and RRSIG Resource Records for DNSSEC
RFC 5702

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Network Working Group                                          J. Jansen
Request for Comments: 5702                                    NLnet Labs
Category: Standards Track                                   October 2009

                  Use of SHA-2 Algorithms with RSA in
              DNSKEY and RRSIG Resource Records for DNSSEC

Abstract

   This document describes how to produce RSA/SHA-256 and RSA/SHA-512
   DNSKEY and RRSIG resource records for use in the Domain Name System
   Security Extensions (RFC 4033, RFC 4034, and RFC 4035).

Status of This Memo

   This document specifies an Internet standards track protocol for the
   Internet community, and requests discussion and suggestions for
   improvements.  Please refer to the current edition of the "Internet
   Official Protocol Standards" (STD 1) for the standardization state
   and status of this protocol.  Distribution of this memo is unlimited.

Copyright Notice

   Copyright (c) 2009 IETF Trust and the persons identified as the
   document authors.  All rights reserved.

   This document is subject to BCP 78 and the IETF Trust's Legal
   Provisions Relating to IETF Documents
   (http://trustee.ietf.org/license-info) in effect on the date of
   publication of this document.  Please review these documents
   carefully, as they describe your rights and restrictions with respect
   to this document.  Code Components extracted from this document must
   include Simplified BSD License text as described in Section 4.e of
   the Trust Legal Provisions and are provided without warranty as
   described in the BSD License.

Jansen                      Standards Track                     [Page 1]
RFC 5702                    DNSSEC RSA/SHA-2                October 2009

Table of Contents

   1. Introduction ....................................................2
   2. DNSKEY Resource Records .........................................3
      2.1. RSA/SHA-256 DNSKEY Resource Records ........................3
      2.2. RSA/SHA-512 DNSKEY Resource Records ........................3
   3. RRSIG Resource Records ..........................................3
      3.1. RSA/SHA-256 RRSIG Resource Records .........................4
      3.2. RSA/SHA-512 RRSIG Resource Records .........................4
   4. Deployment Considerations .......................................5
      4.1. Key Sizes ..................................................5
      4.2. Signature Sizes ............................................5
   5. Implementation Considerations ...................................5
      5.1. Support for SHA-2 Signatures ...............................5
      5.2. Support for NSEC3 Denial of Existence ......................5
   6. Examples ........................................................6
      6.1. RSA/SHA-256 Key and Signature ..............................6
      6.2. RSA/SHA-512 Key and Signature ..............................7
   7. IANA Considerations .............................................8
   8. Security Considerations .........................................8
      8.1. SHA-1 versus SHA-2 Considerations for RRSIG
           Resource Records ...........................................8
      8.2. Signature Type Downgrade Attacks ...........................8
   9. Acknowledgments .................................................9
   10. References .....................................................9
      10.1. Normative References ......................................9
      10.2. Informative References ....................................9

1.  Introduction

   The Domain Name System (DNS) is the global, hierarchical distributed
   database for Internet Naming.  The DNS has been extended to use
   cryptographic keys and digital signatures for the verification of the
   authenticity and integrity of its data.  [RFC4033], [RFC4034], and
   [RFC4035] describe these DNS Security Extensions, called DNSSEC.

   RFC 4034 describes how to store DNSKEY and RRSIG resource records,
   and specifies a list of cryptographic algorithms to use.  This
   document extends that list with the algorithms RSA/SHA-256 and RSA/
   SHA-512, and specifies how to store DNSKEY data and how to produce
   RRSIG resource records with these hash algorithms.

   Familiarity with DNSSEC, RSA, and the SHA-2 [FIPS.180-3.2008] family
   of algorithms is assumed in this document.

Jansen                      Standards Track                     [Page 2]
RFC 5702                    DNSSEC RSA/SHA-2                October 2009

   To refer to both SHA-256 and SHA-512, this document will use the name
   SHA-2.  This is done to improve readability.  When a part of text is
   specific for either SHA-256 or SHA-512, their specific names are
   used.  The same goes for RSA/SHA-256 and RSA/SHA-512, which will be
   grouped using the name RSA/SHA-2.

   The term "SHA-2" is not officially defined but is usually used to
   refer to the collection of the algorithms SHA-224, SHA-256, SHA-384,