Re: [BUGFIX] crypto: Fix ctr(aes) testing by specifying geniv

From: Herbert Xu
Date: Thu Aug 13 2009 - 21:05:37 EST


On Fri, Aug 14, 2009 at 09:01:07AM +0800, Huang Ying wrote:
>
> I see seqiv is used in rfc3686 mode, it means seqiv can not be used on
> raw counter mode but can be used for rfc3686?

Yeah, with rfc3686 a portion of the counter is available for
counting bytes within each request. This allows a sequential
IV to be safely used as each IV is essentially 2^32 blocks apart.

With raw counter mode as soon as you process two blocks in one
request the next IV would collide with one that has alreay been
used.

Cheers,
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