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Versions: 00                                                            
   IP Security working group                Baiju V. Patel,
   Internet Draft                           Michael Jeronimo,
                                            Intel Corp.
   Document: draft-ietf-ipsec-isakmp-SA-revised-00.txt
   November, 1997
  
  
             Revised SA negotiation mode for ISAKMP/Oakley
  
  
   Status of this Memo
  
   This document is an Internet Draft.  Internet Drafts are working
   documents of the Internet Engineering Task Force (IETF), its Areas,
   and its Working Groups.  Note that other groups may also distribute
   working documents as Internet Drafts.
  
   Internet Drafts are draft documents valid for a maximum of six
   months.  Internet Drafts may be updated, replaced, or obsoleted by
   other documents at any time.  It is not appropriate to use Internet
   Drafts as reference material or to cite them other than as a
   "working draft" or "work in progress".
  
   To learn the current status of any Internet-Draft, please check the
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   Directories on ds.internic.net, nic.nordu.net, ftp.isi.edu, or
   munnari.oz.au.
  
   A revised version of this draft document will be submitted to the
   RFC editor as a Proposed Standard for the Internet Community.
   Discussion and suggestions for improvement are requested.  This
   document will expire before February 1998. Distribution of this
   draft is unlimited.
  
  
  
  
   1.  Abstract
  
  
   ISAKMP/OAKLEY [2][3] is the key management protocol defined by IPSEC
   working to be a framework for authentication, security association
   negotiation and key management. The protocol defines two phases
   whereby, in the phase 1, the peers are authenticates, the security
   association (SA) for ISAKMP/Oakley, and keying material is agreed
   upon by the peers to secure ISAKMP messages. The phase 2 is used to
   negotiate security association for security applications (e.g.,
   IPSEC AH and ESP). When perfect forward secrecy is required, phase 2
   is also used to exchange keying material for the application.
   However, when perfect forward secrecy is not a requirement, the
   keying material from the phase 1 is used to generate session keys
   for the secure communication applications.
  
   The proposal in this document is based on the observation that when
   perfect forward secrecy is not a requirement, if application
  
  
   Patel                                                             1
  
        draft-ietf-ipsec-isakmp-SA-revised-00.txt      11/21/97
  
   specific SA was negotiated during phase 1, the application can start
   immediately after phase 1. The phase 2 can be used subsequently for
   key refresh on per need bases in the future. Therefore, this
   proposal reduces startup time for communication and improves the
   efficiency of the protocol.
  
   Remark: This document is NOT self-contained, it is intended as an
   addendum to [2][3]. Thus, it is best read in conjunction with
   [2][3].
  
  
   2.  Revised modes of ISAKMP/Oakley
  
  
   2.1.
        Notation
  
   SA_App: is an SA negotiation payload with one or more proposals
  
   specific to the application (e.g., IPSEC AH or ESP),
  
   SA_App_p: is the entire body of the SA_App payload (minus the ISAKMP
  
   generic header) -- i.e., the DOI, situation, all proposals, and all
  
   transforms included in SA_App.
  
  
   HASH_I =
  
     prf(SKEYID, g^xi | g^xr | CKY-I | CKY-R | Sap | SA_App_p | IDii)
  
   HASH_R =
  
     prf(SKEYID, g^xr | g^xi | CKY-R | CKY-I | SAp | SA_App_p | IDir)
  
   Observe that the HASH-I and HASH-R functions in this revised mode
  
   include application specific SA's. This a change from the
  
   specification in [3].
  
  
   Unless otherwise specified, all the notations used in this document
  
   are same as those in [3].
  
  
   2.2.
        Phase 1 authenticated with Signatures
  
  
   Main Mode with signature authentication is described as follows:
  
   Initiator                          Responder
  
   ----------                         -----------
  
   HDR, SA                     -->
  
                               <--    HDR, SA
  
   HDR, KE, Ni                 -->
  
                               <--    HDR, KE, Nr
  
   HDR*, IDii, SA_App [ CERT, ] SIG_I -->
  
                               <--    HDR*, IDir, [ CERT, ] SIG_R
  
  
   Aggressive mode with signatures in conjunction with ISAKMP is
  
   described as follows:
  
  
       Initiator                          Responder
  
     -----------                        -----------
  
   HDR, SA, SA_App, KE, Ni, IDii       -->
  
  
   Patel and jeronimo                                                2
  
        draft-ietf-ipsec-isakmp-SA-revised-00.txt      11/21/97
  
  
                               <--    HDR, SA, SA_App, KE, Nr,
  
                                        IDir, [ CERT, ] SIG_R
  
   HDR, [ CERT, ] SIG_I        -->
  
  
  
   2.3.
        Phase 1 Authenticated With Public Key Encryption
  
   When using encryption for authentication, Main Mode is defined as
   follows.
  
   Initiator                        Responder
   -----------                      -----------
   HDR, SA                   -->
                             <--    HDR, SA
   HDR, KE, [ HASH(1), ]
        <IDii>PubKey_r,
        <Ni>PubKey_r          -->
                                     HDR, KE, <IDir>PubKey_i,
                             <--            <Nr>PubKey_i
   HDR*, SA_App, HASH_I              -->
                             <--    HDR*, SA_App, HASH_R
  
      Aggressive Mode authenticated with encryption is described as
      follows:
  
    Initiator                        Responder
    -----------                      -----------
    HDR, SA, SA_App, [ HASH(1),] KE,
       <IDii>Pubkey_r,
       <Ni>Pubkey_r           -->
                                     HDR, SA, SA_App, KE,
                                          <IDir>PubKey_i,
                              <--         <Nr>PubKey_r, HASH_R
    HDR, HASH_I               -->
  
      Where HASH(1) is a hash (using the negotiated hash function) of
   the certificate which the initiator is using to encrypt the nonce
   and identity.
  
  
  2.4. Phase 1 Authenticated With a Pre-Shared Key
  
  
      When doing a pre-shared key authentication, Main Mode is defined
   as follows:
  
   Initiator                        Responder
   ----------                       -----------
   HDR, SA             -->
                       <--    HDR, SA
   HDR, KE, Ni         -->
                       <--    HDR, KE, Nr
   HDR*, SA_App IDii, HASH_I  -->
                       <--    HDR*, SA_App, IDir, HASH_R
  
  
  
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        draft-ietf-ipsec-isakmp-SA-revised-00.txt      11/21/97
  
   Aggressive mode with a pre-shared key is described as follows:
  
   Initiator                        Responder
   -----------                      -----------
   HDR, SA, SA_App, KE, Ni, IDii -->
                         <--    HDR, SA, SA_App, KE, Nr, IDir, HASH_R
   HDR, HASH_I           -->
  
  
   3.  Security Considerations
  
  
   This draft defines a security protocol.
  
  
  
   4.  References
  
  
   [1].
        Bradner, S, "Key words for use in RFCs to Indicate
  
  Requirement Levels", RFC 2119, Harvard University, March 1997.
  
   [2].
        Maughhan, D., Schertler, M., Schneider, M., and Turner, J.,
  
  "Internet Security Association and Key Management Protocol
  
  (ISAKMP)",    version 8, draft-ietf-ipsec-isakmp-08.{ps,txt}.
  
   [3].
        D. Harkins, D. Carrel, "The resolution of ISAKMP with
  
  Oakley", Internet Draft, <draft-ietf-ipsec-isakmp-oakley-04.txt>,
  
  July 1997
  
   [4].
        Krawczyk, H., Bellare, M., Canetti, R., "HMAC: Keyed-Hashing
  
  for Message Authentication", RFC 2104, February 1997.
  
   [5].
        Schneier, B., "Applied Cryptography, Protocols, Algorithms,
  
  and Source Code in C", 2nd edition.
  
  
  
   5.  Acknowledgments
  
  
   This draft is largely based on the Dan Harkin's IETF draft on
   ISAKMP/OAKLEY resolution.
  
  
   6.  Author's Addresses
  
  
   Baiju V. Patel
   Intel Corp
   2511 NE 25th Ave
   Hillsboro, OR 97124
   Phone: 503 264 2422
   Email: baiju@mailbox.jf.intel.com
  
   Michael Jeronimo
   Intel Corp
   2511 NE 25th Ave
   Hillsboro, OR 97124
   Phone: 503 264 5970
   Email: jeronim@ccm.jf.intel.com
  
  
  
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        draft-ietf-ipsec-isakmp-SA-revised-00.txt      11/21/97
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
   Patel and jeronimo                                                5