Re: [Cfrg] draft-housley-ccm-mode-00.txt

[David Wagner <daw@cs.berkeley.edu>]

> An advantage I can see is the use of the same key for both 
> authentication and encryption. [...] Using the same key 
> halves the key storage requirements for an 802.11 base station.

It is easy to achieve the same thing with the standard generic
composition.  You pick a 128-bit key, and derive the encryption and
authentication keys separately using a PRF: Ke = F_K(0), Ka = F_K(1).
This is all very standard, and is done in IPSec and TLS, for instance.
So I don't see this as an advantage or an disadvantage.

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