Re: [Emu] EAP-GPSK: Ciphersuites

I guess we agree to disagree.  The addition integrity checksum is 
spurious in my view and I believe we can define things so that 
combined modes can be employed without encrypting anything, so I am 
somewhat confused here.  What's your opinion on the latter part of my email?

thanks,
Lakshminath

At 05:12 PM 8/22/2006, Hannes Tschofenig wrote:
>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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