Re: [Emu] Review of draft-clancy-emu-eap-shared-secret-01

On Wed, Jul 12, 2006 at 09:50:15AM -0700, M. Vanderveen wrote:

>   Personally I'm somewhat disappointed that AES-EAX was chosen, even though it's fame is that is simpler than CCM, which is what 802.11i proposes. Not having participated in the discussions on algorithm selection, I am wondering if anybody have given thought to what can be done to help the power and memory-limited mobile, who now has to have *hardware* to please everybody: the EAP for network access, SAP 4-way handshake for link-layer access, MobileIP for mobility, VPN to sooothe operator concerns, etc, to name a few possibilities. Not all of these must be done in hw, of course. What do the implementors have to say about these?

It depends.. So far, I have only needed to implement AES-EAX because of
EAP-PSK and now EAP-GPSK, i.e., I haven't needed it for anything else in
IEEE 802.11/802.1X/EAP area. I did need to implement CCM for IEEE
802.11i. However, it is used only for data frame encryption/decryption
(IEEE 802.11i uses AES key wrap algorithm, RFC 3394, in higher layer
operations) and in many designs, it is not easily available for the EAP
implementation. CCMP (AES-CCM) may be implemented in the hardware/
firmware/device driver and there may not be an interface for the EAP
server/peer (usually, a user space application) to access the same
implementation. Sure, it is possible to re-use the same code, but that
may not be the most common solution. In addition, adding another mode of
AES in software is not really taking that much space.

In other words, I'm not too concerned from the view point of
implementation size of EAX vs. CCM. However, I would have to admit that
it would have been easier to implement EAP-PSK (and now GPSK) if CCM
had been used instead of EAX since I first had to figure out what
exactly EAX is doing whereas I was already familiar with CCM because of
IEEE 802.11i background.

-- 
Jouni Malinen                                            PGP id EFC895FA

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