Re: Patch for TLS 1.2 DHE* cipher support in uwimap/panda?

"Erik Kangas, Ph.D." <[email protected]> Wed, 05 Apr 2017 22:23:41 +0000
Newsgroups gmane.mail.imap.uw.c-client
Message-ID <[email protected]>
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Thanks.

We already pre-generate the DH parameters for sendmail and have them=20
sitting around in a dhparms.pem file unique to the server.  I wonder if=20
anyone has created a patch that allows UW IMAP to read such a file and=20
supply the parameters?

-Erik Kangas

On April 5, 2017 06:07:15 pm EDT, "Dan Lukes" <[email protected]> wrote:

Erik Kangas, Ph.D. wrote:
> Has anyone found a way to get the Diffie Hellman TLS v1.2 ciphers (e.g.
> DHE-RSA-AES256-GCM-SHA384) to work with UW IMAP / Panda IMAP?

In order to perform a DH key exchange the server must use a DH group (DH
parameters) and generate a DH key.

UW IMAP neither generate DH parameters on the fly nor supply the
parameters - thus no DHE can be negotiated.

You may patch the code and use SSL_CTX_set_options(3) to set
SSL_OP_SINGLE_DH_USE option, but generating DH parameters on the fly is
extremely time consuming.

Dan


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<div>Thanks.<br />
<br />
We already pre-generate the DH parameters for sendmail and have them sittin=
g around in a dhparms.pem file unique to the server. &nbsp;I wonder if anyo=
ne has created a patch that allows UW IMAP to read such a file and supply t=
he parameters?<br />
<br />
-Erik Kangas</div>
</div>
&nbsp;

<div style=3D"padding:3px 0 3px 0;border-top:1px solid #DDD; border-bottom:=
 1px solid #DDD;margin:3px 0 3px 0">On April 5, 2017 06:07:15 pm EDT, &quot=
;Dan Lukes&quot; &lt;[email protected]&gt; wrote:</div>
<br />
<br />
Erik Kangas, Ph.D. wrote:<br />
&gt; Has anyone found a way to get the Diffie Hellman TLS v1.2 ciphers (e.g=
.<br />
&gt; DHE-RSA-AES256-GCM-SHA384) to work with UW IMAP / Panda IMAP?<br />
<br />
In order to perform a DH key exchange the server must use a DH group (DH<br=
 />
parameters) and generate a DH key.<br />
<br />
UW IMAP neither generate DH parameters on the fly nor supply the<br />
parameters - thus no DHE can be negotiated.<br />
<br />
You may patch the code and use SSL_CTX_set_options(3) to set<br />
SSL_OP_SINGLE_DH_USE option, but generating DH parameters on the fly is<br =
/>
extremely time consuming.<br />
<br />
<br />
Dan<br />
&nbsp;
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