issues with OpenPGP certificate verification

Simon Josefsson simon at josefsson.org
Mon Apr 28 20:03:33 CEST 2008


Hi Daniel.  Thanks for reporting this.  I've modified them so that they
must be fixed before v2.4.  I haven't had time to look at them yet, but
I hope Nikos and you will be able to come up with something that solves
the problem.  I'll revisit this when I get closer to the release.

/Simon

Daniel Kahn Gillmor <dkg-debian.org at fifthhorseman.net> writes:

> Hey Folks--
>
> I just opened a couple tickets concerning what appear to be serious
> problems with GnuTLS's OpenPGP certificate verification:
>
>  * gnutls-cli continues connection when certificate User ID does not
>    match hostname (even without --insecure):
>
>      http://trac.gnutls.org/cgi-bin/trac.cgi/ticket/31
>
>    This is equivalent to accepting a valid TLS certificate from
>    https://evil.com/ even though the connection was made to
>    https://good.com/
>
>  * gnutls will accept an unsigned UserID as a hostname match as long
>    as some signed UserID exists:
>
>      http://trac.gnutls.org/cgi-bin/trac.cgi/ticket/32
>
>    This appears to be a problem with the way that the library offers
>    information about the UserIDs in the OpenPGP certificates.  Since
>    each UserID in an OpenPGP cert can be signed by 0 or more keys
>    (other than the primary key), there needs to be a way to check the
>    validity of specific UserIDs, not just the certificate as a whole.
>
> As usual, if you want more details, just post to the tickets, and i'll
> provide whatever help i can.
>
> I'm excited to see the library offering OpenPGP features for TLS, but
> these problems are significant security concerns.  i want to make sure
> that the first major implementation of this extension is secure!
>
> Thanks for all the work on this,
>
>        --dkg
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