[stunnel-users] using ECDH with stunnel

Thu Feb 11 20:21:31 CET 2010

On Thu, 2010-02-11 at 18:27 +0100, Michal Trojnara wrote:
> Carl wrote:
> > Is is possible to use ECDH with stunnel?
> > 
> > When using s_server and specifying the cipher I can establish a
> > connection. But when using stunnel and specifing the same cipher, the
> > connection is rejected with "no shared cipher".
> 
> You are correct.  Stunnel currently does not generate temporary ECDH keys
> with EC_KEY_new_by_curve_name() function.
> 
> It should be possible to provide ECDH parameters with a certificate
> instead:
> http://www.openssl.org/docs/apps/req.html
> It's probably also a better choice for performance, as key generation could
> be a CPU-intensive operation.
> 
> What do you think?

Ok, I was confused on what the ECDH acronym meant. Sorry about that. I'm
trying to support the cipher DHE-RSA-AES256-SHA which uses ephemeral DH
which is not elliptical curve DH (ECDH).

So for the DHE-RSA-AES256-SHA cipher, the server certificate needs to
have DH parameters and DH is not compiled in stunnel by default (as
described in the stunnel faq.)

I have recompiled stunnel with DH enabled and I am happy to report the
DHE ciphers are now working with stunnel.

Thanks for your support and great open source software.

Carl