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Versions: (draft-kivinen-ipsecme-oob-pubkey) 00

IP Security Maintenance and Extensions (ipsecme)              T. Kivinen
Internet-Draft                                             INSIDE Secure
Updates: RFC 5996 (if approved)                               P. Wouters
Intended status: Standards Track                                 Red Hat
Expires: October 10, 2013                                  H. Tschofenig
                                                  Nokia Siemens Networks
                                                          April 08, 2013


                     More Raw Public Keys for IKEv2
                  draft-ietf-ipsecme-oob-pubkey-00.txt

Abstract

   The Internet Key Exchange Version 2 (IKEv2) protocol currently only
   supports raw RSA keys.  In some environments it is useful to make use
   of other types of public keys, such as those based on Elliptic Curve
   Cryptography.  This documents adds support for other types of raw
   public keys to IKEv2 and obsoletes the old raw RSA key format.

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
   working documents as Internet-Drafts.  The list of current Internet-
   Drafts is at http://datatracker.ietf.org/drafts/current/.

   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 October 10, 2013.

Copyright Notice

   Copyright (c) 2013 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



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   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 Simplified BSD License.

Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   2
   2.  Terminology . . . . . . . . . . . . . . . . . . . . . . . . .   3
   3.  Certificate Encoding Payload  . . . . . . . . . . . . . . . .   3
   4.  Old Raw RSA Key Certificate Type  . . . . . . . . . . . . . .   4
   5.  Security Considerations . . . . . . . . . . . . . . . . . . .   4
   6.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .   5
   7.  Acknowledgements  . . . . . . . . . . . . . . . . . . . . . .   5
   8.  References  . . . . . . . . . . . . . . . . . . . . . . . . .   5
     8.1.  Normative References  . . . . . . . . . . . . . . . . . .   5
     8.2.  Informative References  . . . . . . . . . . . . . . . . .   5
   Appendix A.  Examples . . . . . . . . . . . . . . . . . . . . . .   6
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .   7

1.  Introduction

   Secure DNS allows public keys to be associated with domain names for
   usage with security protocols like Internet Key Exchange Version 2
   (IKEv2) [RFC5996] and Transport Layer Security (TLS) but it relies on
   extensions in those protocols to be specified.

   IKEv2 already offers support for PKCS #1 encoded RSA keys, i.e., a
   DER- encoded RSAPublicKey structure (see [RSA] and [RFC3447]).  Other
   raw public keys types are, however, not supported.

   The TLS Out-of-Band Public Key Validation specification
   ([I-D.ietf-tls-oob-pubkey]) adds generic support for raw public keys
   to TLS by re-using the SubjectPublicKeyInfo format from the X.509
   Public Key Infrastructure Certificate profile [RFC5280].

   This document is similar than the TLS Out-of-Band Public Key
   Validation specification, and applies the concept to IKEv2 to support
   all public key formats defined by PKIX.  This approach also allows
   future public key extensions to be supported without the need to
   introduce further enhancements to IKEv2.

   To support new types of public keys in IKEv2 the following changes
   are needed:

   o  A new Certificate Encoding format needs to be defined for carrying
      the SubjectPublicKeyInfo structure.  Section 3 specifies this new
      encoding format.




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   o  A new Certificate Encoding type needs to be allocated from the
      IANA registry.  Section 6 contains this request to IANA.

2.  Terminology

   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.  Certificate Encoding Payload

   Section 3.6 of RFC 5996 defines the Certificate payload format as
   shown in Figure 1.

                        1                   2                   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
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   | Next Payload  |C|  RESERVED   |         Payload Length        |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   | Cert Encoding |                                               |
   +-+-+-+-+-+-+-+-+                                               |
   ~                       Certificate Data                        ~
   |                                                               |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

                   Figure 1: Certificate Payload Format.

   o  Certificate Encoding (1 octet) - This field indicates the type of
      certificate or certificate-related information contained in the
      Certificate Data field.

   Certificate Encoding                 Value
   ----------------------------------------------------
   Raw Public Key                       TBD


   o  Certificate Data (variable length) - Actual encoding of the
      certificate data.  The type of certificate is indicated by the
      Certificate Encoding field.

   When the certificate encoding type 'Raw Public Key' is used then the
   Certificate Data only contains the SubjectPublicKeyInfo part of the
   PKIX certificate.

   In the case of the Certificate Request payload the Certification
   Authority field MUST be empty if the "Raw Public Key" certificate
   encoding is used.




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   Note, that we do follow public key processing rules of the section
   1.2 of the Additional Algorithms and Identifiers for RSA Cryptography
   for PKIX ([RFC4055]) even when the SubjectPublicKeyInfo is not part
   of the certificate, but sent here.  This means RSASSA-PSS and RSASSA-
   PSS-params inside the SubjectPublicKeyInfo needs to followed.

4.  Old Raw RSA Key Certificate Type

   After this there would be two ways of sending Raw RSA public keys in
   the IKEv2: The original IKEv2 mechanism (Raw RSA Key, encoding value
   11), and the new format defined here.  The old Raw RSA Key encoding
   has not been widely used.  The IKEv2 protocol already supports a
   method to indicate what certificate encoding formats are supported,
   i.e.  a peer can send one or multiple Certificate Request payload
   with the certificate encoding types it supports.  From this list the
   recipient can see what formats are supported and select one which is
   used to send Certificate back.

   Implementations conforming to this document MUST use the new format
   defined here for the raw public keys, regardless of the key type.
   This means that old Raw RSA Key encoding value 11 MUST NOT be used
   for certificate or certificate request payloads.

   Note, that recipients can simply process the old Raw RSA key
   encodings just like any other unsupported or unknown certificate
   encoding type, i.e.  skip over it, recipients MUST NOT consider
   receiving such payloads as fatal error (if other end sends such
   payloads, it is completely possible that the peers do not have common
   format for certificate encoding and the authentication will fail
   because of that).

5.  Security Considerations

   An IKEv2 deployment using raw public keys needs to utilize an out-of-
   band public key validation procedure to be confident in the
   authenticity of the keys being used.  One such mechanism is to use a
   configuration mechanism for provisioning raw public keys into the
   IKEv2 software.  A suitable deployment is likely to be found with
   smart objects.  Yet another approach is to rely on secure DNS to
   associate public keys to be associated with domain names using the
   IPSECKEY DNS RRtype [RFC4025].  More information can be found in DNS-
   Based Authentication of Named Entities (DANE) [RFC6394].

   This document does not change the assumptions made by the IKEv2
   specifications since "Raw RSA Key" support is already available in
   IKEv2.  This document only generalizes the raw public key support and
   obsoletes the old "Raw RSA Key" format.




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6.  IANA Considerations

   This document allocates a new value from the IKEv2 Certificate
   Encodings registry:

   TBD      Raw Public Key


   This document also obsoletes the old value in the same registry, and
   the entry for "Raw RSA Key" should be changed to:

   11       Obsoleted (was Raw RSA Key)


7.  Acknowledgements

   This document copies parts from the similar TLS document
   ([I-D.ietf-tls-oob-pubkey]).

8.  References

8.1.  Normative References

   [RFC2119]  Bradner, S., "Key words for use in RFCs to Indicate
              Requirement Levels", BCP 14, RFC 2119, March 1997.

   [RFC5280]  Cooper, D., Santesson, S., Farrell, S., Boeyen, S.,
              Housley, R., and W. Polk, "Internet X.509 Public Key
              Infrastructure Certificate and Certificate Revocation List
              (CRL) Profile", RFC 5280, May 2008.

   [RFC5996]  Kaufman, C., Hoffman, P., Nir, Y., and P. Eronen,
              "Internet Key Exchange Protocol Version 2 (IKEv2)", RFC
              5996, September 2010.

8.2.  Informative References

   [I-D.ietf-tls-oob-pubkey]
              Wouters, P., Tschofenig, H., Gilmore, J., Weiler, S., and
              T. Kivinen, "Out-of-Band Public Key Validation for
              Transport Layer Security (TLS)", draft-ietf-tls-oob-
              pubkey-07 (work in progress), February 2013.

   [RFC3447]  Jonsson, J. and B. Kaliski, "Public-Key Cryptography
              Standards (PKCS) #1: RSA Cryptography Specifications
              Version 2.1", RFC 3447, February 2003.





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   [RFC4025]  Richardson, M., "A Method for Storing IPsec Keying
              Material in DNS", RFC 4025, March 2005.

   [RFC4055]  Schaad, J., Kaliski, B., and R. Housley, "Additional
              Algorithms and Identifiers for RSA Cryptography for use in
              the Internet X.509 Public Key Infrastructure Certificate
              and Certificate Revocation List (CRL) Profile", RFC 4055,
              June 2005.

   [RFC4754]  Fu, D. and J. Solinas, "IKE and IKEv2 Authentication Using
              the Elliptic Curve Digital Signature Algorithm (ECDSA)",
              RFC 4754, January 2007.

   [RFC5480]  Turner, S., Brown, D., Yiu, K., Housley, R., and T. Polk,
              "Elliptic Curve Cryptography Subject Public Key
              Information", RFC 5480, March 2009.

   [RFC6394]  Barnes, R., "Use Cases and Requirements for DNS-Based
              Authentication of Named Entities (DANE)", RFC 6394,
              October 2011.

   [RSA]      R. Rivest, , A. Shamir, , and L. Adleman, "A Method for
              Obtaining Digital Signatures and Public-Key
              Cryptosystems", February 1978.

Appendix A.  Examples

   This appendix provides examples of the actual packets sent on the
   wire.  This uses the 256-bit ECDSA private/public key pair defined in
   the section 8.1.  of the IKEv2 ECDSA document [RFC4754].

   The public key is as followed:

   o  Algorithm : id-ecPublicKey (1.2.840.10045.2.1)

   o  Fixed curve: secp256r1 (1.2.840.10045.3.1.7)

   o  Public key x coordinate : cb28e099 9b9c7715 fd0a80d8 e47a7707
      9716cbbf 917dd72e 97566ea1 c066957c

   o  Public key y coordinate : 2b57c023 5fb74897 68d058ff 4911c20f
      dbe71e36 99d91339 afbb903e e17255dc

   The SubjectPublicKeyInfo ASN.1 object is as follows:

   0000 :     SEQUENCE
   0002 :       SEQUENCE
   0004 :         OBJECT IDENTIFIER  id-ecPublicKey (1.2.840.10045.2.1)



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   000d :         OBJECT IDENTIFIER  secp256r1 (1.2.840.10045.3.1.7)
   0017 :       BIT STRING  (66 bytes)
   00000000: 0004 cb28 e099 9b9c 7715 fd0a 80d8 e47a
   00000010: 7707 9716 cbbf 917d d72e 9756 6ea1 c066
   00000020: 957c 2b57 c023 5fb7 4897 68d0 58ff 4911
   00000030: c20f dbe7 1e36 99d9 1339 afbb 903e e172
   00000040: 55dc


   The first byte (00) of the bit string indicates that there is no
   "number of unused bits", and the second byte (04) indicates
   uncompressed form ([RFC5480]).  Those two octets are followed by the
   values of X and Y.

   The final encoded SubjectPublicKeyInfo object is as follows:

   00000000: 3059 3013 0607 2a86 48ce 3d02 0106 082a
   00000010: 8648 ce3d 0301 0703 4200 04cb 28e0 999b
   00000020: 9c77 15fd 0a80 d8e4 7a77 0797 16cb bf91
   00000030: 7dd7 2e97 566e a1c0 6695 7c2b 57c0 235f
   00000040: b748 9768 d058 ff49 11c2 0fdb e71e 3699
   00000050: d913 39af bb90 3ee1 7255 dc


   This will result the final IKEv2 Certificate Payload to be:

   00000000: NN00 0060 XX30 5930 1306 072a 8648 ce3d
   00000010: 0201 0608 2a86 48ce 3d03 0107 0342 0004
   00000020: cb28 e099 9b9c 7715 fd0a 80d8 e47a 7707
   00000030: 9716 cbbf 917d d72e 9756 6ea1 c066 957c
   00000040: 2b57 c023 5fb7 4897 68d0 58ff 4911 c20f
   00000050: dbe7 1e36 99d9 1339 afbb 903e e172 55dc


   Where the NN will be the next payload type (i.e.  that value depends
   on what is the next payload after this certificate payload).

   Note to the RFC editor / IANA, replace the XX above with the newly
   allocated Raw Public Key number, and remove this note.

Authors' Addresses










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   Tero Kivinen
   INSIDE Secure
   Eerikinkatu 28
   HELSINKI  FI-00180
   FI

   Email: kivinen@iki.fi


   Paul Wouters
   Red Hat

   Email: pwouters@redhat.com


   Hannes Tschofenig
   Nokia Siemens Networks
   Linnoitustie 6
   Espoo  02600
   Finland

   Phone: +358 (50) 4871445
   Email: Hannes.Tschofenig@gmx.net
   URI:   http://www.tschofenig.priv.at


























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