slow signature verification with certain keys

[Steven Barker]

On Fri, Aug 31, 2001 at 09:30:33AM +0200, Werner Koch wrote:
> On Thu, 30 Aug 2001 16:24:47 -0500, Steven Barker said:
> 
> > I have noticed that verifying the signatures made by certain keys take much
> > longer than average (45sec to a minute on my P3 550).  One example is the key
> > used to sign the attached message.  I've examined the author's key as best I
> 
> You mean grisu at db.debian.org?

Yes.  I noticed it while reading his signed email, posted to a mailing list.
All of his messages take a long time to be verified.  I asked him about it
and he said he was aware of the problem, but did not know what was causing
it (the message I attached before was his response).  He also wants to know
what is going on.

> Since 1.0.5 key signature are checked everytime the key is used; this
> makes it really slow.  Try that hint from the NEWS file:

<snip>

I tried that, and it has not changed the time it takes to verify his
signature.  It takes far more time to deal with this key than any other,
including ones with many more signatures.

> > Is there a ligitimate reason it should take much longer to verify his
> > signatures, or is it a bug?
> 
> Another reason might be that there is one key signature done with an
> ElGamal signing key - that is much slower than DSA or RSA.

I tried testing this by signing my own key with a dummy ElGamal key I
generated.  It does not change the time to check the signature (I compared
before and after adding the ElGamal signature).

Checking the signatures on his key is not noticeably slower than checking
any other key with as many signatures.

I really don't think this is a case of general poor performance.  I think
something is happening that should not be.  If I can help test anything
else, I'd be happy to.

-- 
Steven Barker                                      scbarker at uiuc.edu
  Al didn't smile for forty years.  You've got to admire a man like that.
  		-- from "Mary Hartman, Mary Hartman"
GnuPG public key: http://www.students.uiuc.edu/~scbarker/pubkey.asc
Fingerprint: 272A 3EC8 52CE F22B F745  775E 5292 F743 EBD5 936B