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Re: [Cfrg] Elliptic Curves - signature scheme: friendliness to low memory implementations (ends on June 3rd)

Simon Josefsson <simon@josefsson.org> Thu, 28 May 2015 19:32 UTC

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From: Simon Josefsson <simon@josefsson.org>
To: Ilari Liusvaara <ilari.liusvaara@elisanet.fi>
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Date: Thu, 28 May 2015 21:32:27 +0200
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Subject: Re: [Cfrg] Elliptic Curves - signature scheme: friendliness to low memory implementations (ends on June 3rd)
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Ilari Liusvaara <ilari.liusvaara@elisanet.fi> writes:

> On Sat, May 23, 2015 at 12:41:31AM -0000, D. J. Bernstein wrote:
>
>> How long are the messages that are actually signed in IETF protocols?
>> For the protocols where the answer is uncontrolled: Do implementations
>> allow messages that don't fit into memory? How do those implementations
>> avoid passing along unverified data? For PGP we know that the answer is
>> "They do pass along unverified data, and this is a security nightmare."
>
> I didn't quickly find list of IETF security protocols, but the only ones
> that come to mind that would need to handle "large" (potentially too much
> to store in memory) amounts of data are OpenPGP and CMS.

Yes -- and OpenPGP has already solved this issue for EdDSA:
https://tools.ietf.org/html/draft-koch-eddsa-for-openpgp-02
I'm sure CMS could use a similar approach.

I believe the stream issue is a red herring.  There are no applications
or protocols waiting for CFRG to recommend a better digital signature
algorithm that supports streaming.

/Simon

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