Re: [Emu] EAP-GPSK: Ciphersuites

Hi Lakshminath,

Lakshminath  Dondeti schrieb:
> At the expense of generating some confusion, here is my take on this:
> 
> The objection is to having to carry multiple integrity checksums in 
> GPSK, if we used the combined mode *and* an integrity algorithm.

I don't agree with you. There is no reason to optimize a few bits in a 
pre-shared secret method.
Note that we are not talking about a protocol for data transfer.
We wanted the flexibility to use different cipher suites. We do not only 
want to use cipher suites that provide authenticated encryption (since 
we almost have nothing to encrypt; currently 1 bit and almost no EAP 
method provides this functionality).

Ciao
Hannes

> 
> I think CCM is fine for instance, the only catch is that we need to make 
> sure and define AAD for CCM carefully to include appropriate data into 
> the integrity checksum calculation.  So, once we define CCM as the mode, 
> we shouldn't need AES-CMAC-128 if encryption is being used.
> 
> I would suggest using CCM and specifying the use of it fully so it can 
> be used without misunderstandings.  If you want me to put some time into 
> writing that up, let me know.
> 
> cheers,
> Lakshminath
> 
> At 10:55 PM 8/20/2006, Hannes Tschofenig 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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>> https://www1.ietf.org/mailman/listinfo/emu
> 
> 

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