David Shaw dshaw at jabberwocky.com
Fri Sep 29 14:41:46 CEST 2006

On Fri, Sep 29, 2006 at 07:11:12AM +0200, Lionel Elie Mamane wrote:
> On Sat, Sep 23, 2006 at 03:15:07PM +0200, Carlo Luciano Bianco wrote:
> > I just try to summarize what I understood from this thread about
> > OpenPGP implementation of DSA and RSA signatures, so you can correct
> > me if I am wrong: ;-) 
> >  - DSA does not support "firewalled hashes"
> Not exactly. Version 3 DSA signatures lack a hash firewall. But
> version 4 DSA signatures do have a hash firewall. The version refers
> not to a version of DSA itself, but the version of the OpenPGP packet
> format being used.

This is not correct.  No DSA signatures in OpenPGP, whether v3 or v4,
have a hash firewall.

> >  - RSA does support "firewalled hashes".
> All RSA signatures (V3 or V4) do have a hash firewall, yes.


It's important to not focus unduly on one thing.  This gives hash
firewalls too much import.  Today it's hash firewalls.  Yesterday it
was hash length.  Before that it was key size, etc, etc.  Make sure
you're not armoring your front door to an absurd degree and leaving a
window open. :)


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