Subject: [Cfrg] Comments on I. Liusvaara signature proposal RE: Signature proposal

From: Dan Brown <[email-masked]>
Date: Mon, 29 Jun 2015 20:11:34 +0000

Hi Ilari,

Two more minor comments/questions:

1) Your proposal's making PH (pre-hash) optional seems to be an instance of
option #3 from the IUF CFRG poll, but the CFRG chairs seem to require option
#1 from the poll.  

2) Does your hash_id mechanism address the issues in:
http://grouper.ieee.org/groups/1363/Research/contributions/HashFunctionFirew
alls.pdf
?  If so, how?  If not, what's their purpose?

Best regards

Dan

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From: Ilari Liusvaara <[email-masked]>
Date: Tue, 30 Jun 2015 10:57:31 +0300

> option #3 from the IUF CFRG poll, but the CFRG chairs seem to require option

AFAICT, the poll result was that IUF is required, non-IUF is not required,
not that IUF is required and non-IUF is prohibited.

That would certainly be consistent with statement "doesn't recommend and
doesn't prohibit" regarding non-IUF.

> ?  If so, how?  If not, what's their purpose?

Yeah, that issue. As for how, the hash_id is included as-is into final
hash input, which should make attacks like presented in the slides much
more difficult.

-Ilari