CMS-12 Error???

[Russ Housley <[e-mail]>]

Steve:

CMS-12, Section 12.3.1 says:
   For key agreement of RC2 key-encryption keys, 128 bits must be
   generated as input to the key expansion process used to compute the
   RC2 effective key [RC2].

X942-07, Section 2.1.3 says:
   ... For RC2-128, which
   requires 128 bits of keying material, the algorithm is run once, with
   a counter value of 1, and the left-most 128 bits are directly con-
   verted to an RC2 key. Similarly, for RC2-40, which requires 40 bits
   of keying material, the algorithm is run once, with a counter value
   of 1, and the leftmost 40 bits are used as the key.

X942-07, Section 2.1.4 says:
   RC2 effective key lengths are equal to RC2 real key lengths.

I think that we are consistent.  CMS-12 is simply mandating that RC2 KEKs
be 128-bit keys, and X942-07 says that the effective key length cannot be
used to weaken the key.

Okay?

Russ

>Return-Path: <[e-mail]>
>Date: Wed, 31 Mar 1999 21:24:42 +0000
>From: Dr Stephen Henson <[e-mail]>
>Organization: Dr S N Henson
>To: "[e-mail]" <[e-mail]>
>Subject: RC2 keylength in CMS.
>
>In CMS there are still a couple of references to the RC2 key length
>being always 128 bits. Specifically 12.3.1 and 12.6. 
>
>Whereas X9.42 refelects the change and that RC2 effective and real key
>lengths are equal.
>
>Steve.
>-- 
>Dr Stephen N. Henson.   http://www.drh-consultancy.demon.co.uk/
>Personal Email: [e-mail] 
>Senior crypto engineer, Celo Communications: http://www.celocom.com/
>Core developer of the   OpenSSL project: http://www.openssl.org/
>Business Email: [e-mail] PGP key: via homepage.
>
>