Hi Hannes,

a few comments inline:

-----Original Message-----
From: Hannes Tschofenig [mailto:[EMAIL PROTECTED]
Sent: Tuesday, August 22, 2006 2:20 AM
To: M. Vanderveen
Cc: [email protected]
Subject: Re: [Emu] EAP-GPSK: Ciphersuites

Hi

let us for a moment assume that RFC 4307 makes some
reasonable algorithm choices (we are talking about IKEv2
here). If we take the text and apply it to EAP-GPSK then we
would produce something like:

Conservative Choice:
-----------------------

(Integrity)
       AUTH_HMAC_SHA1_96        2            [RFC2404]            MUST

(Encryption)
       ENCR_3DES                3         [RFC2451]       MUST-

I agree with Joe that AES is preferable to 3DES, barring some strong legacy considerations.


(Key Derivation)
       PRF_HMAC_SHA1       2          [RFC2104]    MUST

If it is a goal to conform to FIPS-140-2, that goal will probably drive the key derivation function choice in the direction of http:// www.ietf.org/internet-drafts/draft-dang-nistkdf-01.txt. (I like HMAC as a KDF, but I am not confident that it is going to be approved for that purpose within FIPS-140-2.)


(Note that there is no MUST for encryption algorithms specified in RFC
4307.)


Choice for the Future:
-----------------------

(Encryption)
      ENCR_AES_CBC             12        [AES-CBC]       SHOULD+

(Integrity)
      AUTH_AES_XCBC_96         5         [AES-MAC]       SHOULD+

OMAC is a better choice than XCBC, since it is FIPS-140 approved, and has some minor advantages (it's a refinement of XCBC that is unfortunately not backwards compatible with it).


(Key Derivation)
       PRF_AES128_CBC      4          [AESPRF]     SHOULD+


Same KDF considerations as above.

David


Does this sound like a terrible bad idea?

Ciao
Hannes

M. Vanderveen schrieb:
Both are pretty popular. Why not list them both? As for
which one to be
mandatory to implement, someone should to a search through
other systems
(e.g. IEEE, IPSec) and see which one is most popular.

*/Hannes Tschofenig <[EMAIL PROTECTED]>/* wrote:

    Hi all,

    the current version of the document

http://tools.ietf.org/wg/emu/draft-clancy-emu-eap-shared-secret-01.txt
    still supports AES-EAX:


+-----------+----+-------------+---------------+--------------------+
    | CSuite/ | KS | Encryption | Integrity | Key Derivation |
    | Specifier | | | | Function |

+-----------+----+-------------+---------------+--------------------+
    | 0x000001 | 16 | AES-EAX-128 | AES-CMAC-128 | GKDF-128 |

+-----------+----+-------------+---------------+--------------------+

    At the IETF#66 EMU meeting AES CCM was suggested.

    Later, it got the impression that AES-CBC was more
appreciated. Should
    we update the draft with AES-CBC?

    Ciao
    Hannes


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