Re: [Cfrg] RG Last Call - draft-irtf-cfrg-ocb-00

Ted Krovetz <ted@krovetz.net> Fri, 15 February 2013 15:11 UTC

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From: Ted Krovetz <ted@krovetz.net>
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Date: Fri, 15 Feb 2013 07:11:15 -0800
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Subject: Re: [Cfrg] RG Last Call - draft-irtf-cfrg-ocb-00
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> What aspect of OCB do you see as interesting for embedded systems?   If an
> implementation of AES encrypt and decrypt functions are available, then
> the additional circuit or code size of OCB is small.   However, if you are
> designing circuits (as seems to be what you are interested in) then there
> are other modes that are more compact.
> 
> I'm not trying to start a debate on comparing modes, I just want to make
> sure that I understand the issues that you see for embedded crypto.

While not addressing exactly what you're asking Joachim, a lot of system-on-a-chip implementations include an AES engine but pathetic multiplication. In such situations OCB and CCM have a big advantage over other modes because they do very little else besides AES calls.

I have one of these

  http://www.marvell.com/embedded-processors/kirkwood/assets/HW_88F6281_OpenSource.pdf

and have been meaning to implement OCB on it for a while.