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Versions: (draft-sury-dnskey-ed25519) 00 01 draft-ietf-curdle-dnskey-eddsa

Internet Engineering Task Force                                  O. Sury
Internet-Draft                                                    CZ.NIC
Intended status: Standards Track                              R. Edmonds
Expires: August 19, 2016                         Farsight Security, Inc.
                                                       February 16, 2016


                           Ed25519 for DNSSEC
                  draft-ietf-curdle-dnskey-ed25519-01

Abstract

   This document describes how to specify Ed25519 keys and signatures in
   DNS Security (DNSSEC).  It uses the Edwards-curve Digital Security
   Algorithm (EdDSA) with the Ed25519 parameter choice.

Status of This Memo

   This Internet-Draft is submitted in full conformance with the
   provisions of BCP 78 and BCP 79.

   Internet-Drafts are working documents of the Internet Engineering
   Task Force (IETF).  Note that other groups may also distribute
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   Internet-Drafts are draft documents valid for a maximum of six months
   and may be updated, replaced, or obsoleted by other documents at any
   time.  It is inappropriate to use Internet-Drafts as reference
   material or to cite them other than as "work in progress."

   This Internet-Draft will expire on August 19, 2016.

Copyright Notice

   Copyright (c) 2016 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
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   (http://trustee.ietf.org/license-info) in effect on the date of
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   the Trust Legal Provisions and are provided without warranty as
   described in the Simplified BSD License.




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Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   2
   2.  Requirements Language . . . . . . . . . . . . . . . . . . . .   3
   3.  DNSKEY and RRSIG Resource Records for Ed25519 . . . . . . . .   3
   4.  Examples  . . . . . . . . . . . . . . . . . . . . . . . . . .   3
   5.  Acknowledgements  . . . . . . . . . . . . . . . . . . . . . .   4
   6.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .   5
   7.  Implementation Status . . . . . . . . . . . . . . . . . . . .   5
   8.  Security Considerations . . . . . . . . . . . . . . . . . . .   6
   9.  References  . . . . . . . . . . . . . . . . . . . . . . . . .   6
     9.1.  Normative References  . . . . . . . . . . . . . . . . . .   6
     9.2.  Informative References  . . . . . . . . . . . . . . . . .   6
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .   7

1.  Introduction

   DNSSEC, which is broadly defined in [RFC4033], [RFC4034], and
   [RFC4035], uses cryptographic keys and digital signatures to provide
   authentication of DNS data.  Currently, the most popular signature
   algorithm in use is RSA.  [RFC5933] and [RFC6605] later defined the
   use of GOST and NIST specified elliptic curve cryptography in DNSSEC.

   This document defines the use of DNSSEC's DS, DNSKEY, and RRSIG
   resource records (RRs) with a new signing algorithm, Edwards-curve
   Digital Signature Algorithm (EdDSA) with the Ed25519 parameter
   choice.  A more thorough description of EdDSA and Ed25519 can be
   found in [I-D.irtf-cfrg-eddsa].

   Concerns about the real-world security of elliptic curve cryptography
   have emerged since ECDSA was standardized for DNSSEC.  The only two
   curves standardized for use with ECDSA in DNSSEC, NIST P-256 and NIST
   P-384, fail several of the [SafeCurves] security criteria and are
   considered "unsafe".  This document adds an additional elliptic curve
   algorithm and parameter choice to DNSSEC, allowing additional
   flexibility.

   There are three main advantages of the EdDSA algorithm: It does not
   require the use of a unique random number for each signature, there
   are no padding or truncation issues as with ECDSA, and it is more
   resilient to side-channel attacks.

   Ed25519 has a 128-bit security target, which is considered to be
   equivalent in strength to RSA with ~3000-bit keys.  Ed25519 public
   keys are 256 bits (32 bytes) long while signatures are 512 bits (64
   bytes) long.





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   The usage of elliptic curve cryptography in DNSSEC has advantages and
   disadvantages relative to RSA as already described in [RFC6605].
   Even when compared to the use of RSA at reduced relative strengths
   (for instance, 1024- or 2048-bit RSA), Ed25519 still requires
   substantially smaller keys and signatures.  The authors of the study
   Making the Case for Elliptic Curves in DNSSEC [ECCSIZE] came to the
   conclusion that using elliptic curve cryptography rather than RSA in
   DNSSEC can effectively prevent fragmentation of DNSSEC responses as
   well as significantly reduce the amplification attack potential in
   DNSSEC.

   Signing with Ed25519 is significantly faster than signing with either
   equivalently strong RSA or the two existing curves standardized for
   use with the ECDSA algorithm in DNSSEC, while the validation of RSA
   signatures is still significantly faster than the validation of
   Ed25519 signatures.  However, the authors of the TBD [ECCSPEED] study
   came to the conclusion that even if the deployment of elliptic curve
   cryptography in DNSSEC grows to cover 100% of the name space, a
   resolver will still be able to perform validation using a single CPU
   core.

2.  Requirements Language

   The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
   "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
   document are to be interpreted as described in [RFC2119].

3.  DNSKEY and RRSIG Resource Records for Ed25519

   An Ed25519 public key consists of a 32-byte value, which is encoded
   into the Public Key field of a DNSKEY resource record as a simple bit
   string.  The generation of a public key is defined in Chapter 5.1.5
   in [I-D.irtf-cfrg-eddsa].

   An Ed25519 signature consists of a 64-byte value, which is encoded
   into the Signature field of an RRSIG resource record as a simple bit
   string.  The Ed25519 signature algorithm is described in Chapter
   5.1.6 in [I-D.irtf-cfrg-eddsa].

   The algorithm number associated with the use of Ed25519 in DS, DNSKEY
   and RRSIG resource records is TBD.  This registration is fully
   defined in the IANA Considerations section.

4.  Examples







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      This section needs an update after the algorithm for Ed25519 is
                                 assigned.

    Private-key-format: v1.2
    Algorithm: TBD (ED25519)
    PrivateKey: ODIyNjAzODQ2MjgwODAxMjI2NDUxOTAyMDQxNDIyNjI=
    # corresponding to 82260384628080122645190204142262 INT

    example.com. 3600 IN DNSKEY 257 3 TBD (
            l02Woi0iS8Aa25FQkUd9RMzZHJpBoRQwAQEX1SxZJA4= )

    example.com. 3600 IN DS 3613 TBD 2 (
            3aa5ab37efce57f737fc1627013fee07bdf241bd10f3
            b1964ab55c78e79a304b )

    www.example.com. 3600 IN A 192.0.2.1
    www.example.com. 3600 IN RRSIG A TBD 3 3600 (
            20150820000000 20150730000000 3613 example.com.
            cvTRVrU7dwnemQuBq9/E4tlIiRpvWcEmYdzqs6SCQxw6
            qmczBBQGldssMx1TCJnwsEs9ZuA2phPzuJNoon9BCA== )

    Private-key-format: v1.2
    Algorithm: TBD (ED25519)
    PrivateKey: DSSF3o0s0f+ElWzj9E/Osxw8hLpk55chkmx0LYN5WiY=

    example.com. 3600 IN DNSKEY 257 3 TBD (
            zPnZ/QwEe7S8C5SPz2OfS5RR40ATk2/rYnE9xHIEijs= )

    example.com. 3600 IN DS 55648 TBD 2 (
            96401675bc7ecdd541ec0f70d69238c7b95d3bd4de1e
            231a068ceb214d02a4ed )

    www.example.com. 3600 IN A 192.0.2.1
    www.example.com. 3600 IN RRSIG A TBD 3 3600 (
            20150820000000 20150730000000 35452 example.com.
            yuGb9rCNIuhDaRJbuhYHj89Y/3Pi8KWUm7lOt00ivVRGvgulmVX8DgpE
            AFyMP2MKXJrqYJr+ViiCIDwcOIbPAQ==)

5.  Acknowledgements

   Some of the material in this document is copied liberally from
   [RFC6605].

   The authors of this document wish to thank Jan Vcelak, Pieter Lexis
   and Kees Monshouwer for a review of this document.






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6.  IANA Considerations

   This document updates the IANA registry "Domain Name System Security
   (DNSSEC) Algorithm Numbers".  The following entry has been added to
   the registry:

                     +--------------+---------------+
                     | Number       | TBD           |
                     | Description  | Ed25519       |
                     | Mnemonic     | ED25519       |
                     | Zone Signing | Y             |
                     | Trans. Sec.  | *             |
                     | Reference    | This document |
                     +--------------+---------------+

    * There has been no determination of standardization of the use of
                 this algorithm with Transaction Security.

7.  Implementation Status

   (Note to the RFC Editor: please remove this entire section as well as
   the reference to RFC 6982 before publication.)

   This section records the status of known implementations of the
   protocol defined by this specification at the time of posting of this
   Internet-Draft, and is based on a proposal described in [RFC6982].
   The description of implementations in this section is intended to
   assist the IETF in its decision processes in progressing drafts to
   RFCs.  Please note that the listing of any individual implementation
   here does not imply endorsement by the IETF.  Furthermore, no effort
   has been spent to verify the information presented here that was
   supplied by IETF contributors.  This is not intended as, and must not
   be construed to be, a catalog of available implementations or their
   features.  Readers are advised to note that other implementations may
   exist.

   According to [RFC6982], "this will allow reviewers and working groups
   to assign due consideration to documents that have the benefit of
   running code, which may serve as evidence of valuable experimentation
   and feedback that have made the implemented protocols more mature.
   It is up to the individual working groups to use this information as
   they see fit".

   TODO: Fill out this section.







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8.  Security Considerations

   The security level of Ed25519 is slightly under the standard 128-bit
   level ([RFC7748]).  Security considerations listed in [RFC7748] also
   apply to the usage of Ed25519 in DNSSEC.  Such an assessment could,
   of course, change in the future if new attacks that work better than
   the ones known today are found.

9.  References

9.1.  Normative References

   [I-D.irtf-cfrg-eddsa]
              Josefsson, S. and I. Liusvaara, "Edwards-curve Digital
              Signature Algorithm (EdDSA)", draft-irtf-cfrg-eddsa-02
              (work in progress), January 2016.

   [RFC2119]  Bradner, S., "Key words for use in RFCs to Indicate
              Requirement Levels", BCP 14, RFC 2119,
              DOI 10.17487/RFC2119, March 1997,
              <http://www.rfc-editor.org/info/rfc2119>.

   [RFC4033]  Arends, R., Austein, R., Larson, M., Massey, D., and S.
              Rose, "DNS Security Introduction and Requirements",
              RFC 4033, DOI 10.17487/RFC4033, March 2005,
              <http://www.rfc-editor.org/info/rfc4033>.

   [RFC4034]  Arends, R., Austein, R., Larson, M., Massey, D., and S.
              Rose, "Resource Records for the DNS Security Extensions",
              RFC 4034, DOI 10.17487/RFC4034, March 2005,
              <http://www.rfc-editor.org/info/rfc4034>.

   [RFC4035]  Arends, R., Austein, R., Larson, M., Massey, D., and S.
              Rose, "Protocol Modifications for the DNS Security
              Extensions", RFC 4035, DOI 10.17487/RFC4035, March 2005,
              <http://www.rfc-editor.org/info/rfc4035>.

   [RFC7748]  Langley, A., Hamburg, M., and S. Turner, "Elliptic Curves
              for Security", RFC 7748, DOI 10.17487/RFC7748, January
              2016, <http://www.rfc-editor.org/info/rfc7748>.

9.2.  Informative References

   [ECCSIZE]  van Rijswijk-Deij, R., Speroto, A., and A. Pras, "Making
              the Case for Elliptic Curves in DNSSEC", 2015,
              <http://www.sigcomm.org/ccr/papers/2015/
              October/0000000.0000002>.




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   [ECCSPEED]
              van Rijswijk-Deij, R. and K. Hageman, "TBD", 2016, <TBD>.

   [RFC5933]  Dolmatov, V., Ed., Chuprina, A., and I. Ustinov, "Use of
              GOST Signature Algorithms in DNSKEY and RRSIG Resource
              Records for DNSSEC", RFC 5933, DOI 10.17487/RFC5933, July
              2010, <http://www.rfc-editor.org/info/rfc5933>.

   [RFC6605]  Hoffman, P. and W. Wijngaards, "Elliptic Curve Digital
              Signature Algorithm (DSA) for DNSSEC", RFC 6605,
              DOI 10.17487/RFC6605, April 2012,
              <http://www.rfc-editor.org/info/rfc6605>.

   [RFC6982]  Sheffer, Y. and A. Farrel, "Improving Awareness of Running
              Code: The Implementation Status Section", RFC 6982,
              DOI 10.17487/RFC6982, July 2013,
              <http://www.rfc-editor.org/info/rfc6982>.

   [SafeCurves]
              Bernstein, D. and T. Lange, "SafeCurves: choosing safe
              curves for elliptic-curve cryptography", 2016,
              <http://safecurves.cr.yp.to/>.

Authors' Addresses

   Ondrej Sury
   CZ.NIC
   Milesovska 1136/5
   Praha  130 00
   CZ

   Phone: +420 222 745 111
   Email: ondrej.sury@nic.cz


   Robert Edmonds
   Farsight Security, Inc.
   177 Bovet Rd #180
   San Mateo, California  94402
   US

   Phone: +1 650 489 7919
   Email: edmonds@fsi.io








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