Subject: [Gen-art] Gen-ART Review of draft-mcgrew-aes-gmac-esp-01.txt

From: "Spencer Dawkins" <[email-masked]>
Date: Thu, 8 Dec 2005 15:42:06 -0600

I was selected as General Area Review Team reviewer for this specification
(for background on Gen-ART, please see
http://www.alvestrand.no/ietf/gen/art/gen-art-FAQ.html).

Summary: this specification is mostly ready for publication as a Proposed 
Standard. I do have one question, which is probably due to my own ignorance.

The document defines AES-GMAC Additional Authenticated Data (AAD) with 
either 32-bit sequence numbers or 64-bit extended sequence numbers, but it 
was not obvious to me how a receiver parsing this field would know whether 
to interpret the field as 32-bit or 64-bit extended sequence numbers. If 
this is obvious to everyone in the security community, my apologies, but it 
might be nice to add a sentence like "The use of extended sequence numbers 
can be detected by ...".

Thanks,

Spencer 

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From: David McGrew <[email-masked]>
Date: Thu, 8 Dec 2005 13:55:31 -0800

Hi Spencer,

On Dec 8, 2005, at 1:42 PM, Spencer Dawkins wrote:

> Summary: this specification is mostly ready for publication as a  
> Proposed Standard. I do have one question, which is probably due to  
> my own ignorance.
>
> The document defines AES-GMAC Additional Authenticated Data (AAD)  
> with either 32-bit sequence numbers or 64-bit extended sequence  
> numbers, but it was not obvious to me how a receiver parsing this  
> field would know whether to interpret the field as 32-bit or 64-bit  
> extended sequence numbers. If this is obvious to everyone in the  
> security community, my apologies, but it might be nice to add a  
> sentence like "The use of extended sequence numbers can be detected  
> by ...".

that's a good point.  I think that it would be good to cite the  
specific of the ESN option (Section 2.2.1 of draft-ietf-ipsec-esp- 
v3-10.txt) at the point where the spec first mentions it.

David