some crashes on using DSA keys

Simon Josefsson simon at
Mon Apr 20 16:18:26 CEST 2009

Miroslav Kratochvil <exa.exa at> writes:

>> Hi.  Thanks for the report.  Is it possible to trigger this remotely?
> I'm just giving it some research; exploiting this would allow eeeasy
> remote DoS attack.
> The side that was crashing was always the connecting side, but I guess
> that given fixed client (which I'm gonna test in a few minutes) the
> server would have at least some problems too. Only thing needed is to
> trigger that GNUTLS_E_PK_SIG_VERIFY_FAILED from
> _wrap_gcry_pk_verify().
> I'm not really good in investigating this kind of stuff, but I will
> try to do my best ;)

Please see if you can make an unmodified 2.6.5 server crash.

>> Any more details you have would be useful, for example, what exactly do
>> you mean with "use DSA keys in combination with some RSA"?
> Triggered only by using DSA CA keypair (selfsigned) that was used for
> signing DSA keypair. My problem is that I probably generated them
> totally wrong, and therefore triggered that hidden error. (see
> help-gnutls mailinglist where I'm gathering help with the original
> issue :D)

I'll try to help there.

It would be great if you could try to reproduce the problem using only
gnutls-cli and gnutls-serv.


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