bug#15057: 24.3.50; TLS error with reasonably high gnutls-min-prime-bits

[Ted Zlatanov]

On Thu, 30 Jan 2014 16:46:43 -0800 Lars Ingebrigtsen <larsi@gnus.org> wrote: 

LI> Ted Zlatanov <tzz@lifelogs.com> writes:
LMI> gnutls will try to use as high a number of bits as the server supports,
LMI> I think?  So the variables are fine as they are -- they will give you
LMI> all the security that the server says that it can provide.
>> 
LMI> So the warning is kinda semi-bogus.  Or at least ... premature.
>> 
>> It's complicated and depends on the specific TLS priority string on the
>> client and the server's preferences; e.g. ECC seems to negotiate in a
>> completely different way.  I asked on the gnutls-devel mailing list and
>> there's just no good answer AFAICT.

LI> But we're specifying the minimum prime bits that we accept.  Surely the
LI> client and server will negotiate the maximum possible bits they both
LI> accept?

See http://thread.gmane.org/gmane.network.gnutls.general/3181/focus=3299

Try, first of all, appending `!DHE-RSA:!DHE-DSS' to your GnuTLS priority
string to disable DHE.  ECDHE will not have the minimum bits message,
ever, IIUC.

The suggestion from Nikos was to make the above the *default* for all
connections.  I'm OK with that, if it works for you.

Ted