On Tue, Sep 05, 2006 at 12:20:57PM -0400, Evan Daniel wrote:
> On 9/5/06, Michael Rogers <m.rogers at cs.ucl.ac.uk> wrote:
> >-----BEGIN PGP SIGNED MESSAGE-----
> >Hash: SHA1
> >
> >Matthew Toseland wrote:
> >> We will be using STS, at least initially. Which means checking a
> >> signature.
> >
> >Cool, IANAC but I think we should be OK.
> 
> As long as we're signing the data, not its hash; in normal use, one
> signs the hash of the data for compute cost reasons (and IIRC there
> are security reasons too, but I don't have Applied Cryptography in
> front of me right now).  That is secure as long as there is second
> preimage resistance, but the hash function *is* security critical.

Signing the actual data would take a huge amount of space, and there may
be security reasons as well. We need to sign the hash.
> 
> Evan
-- 
Matthew J Toseland - toad at amphibian.dyndns.org
Freenet Project Official Codemonkey - http://freenetproject.org/
ICTHUS - Nothing is impossible. Our Boss says so.
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