[cl-plus-ssl-devel] [CL-PLUS-SSL-DEVEL][PATCH] call SSL_CTX_set_tmp_rsa_callback to support ephemeral ciphers

[Kari Lentz]

This was tested on a Hunchentoot web server running Linux 3.2.0.54-generic
kernel using SBCL 1.1.0.  Before the patch, a Windows NT client with only
standard export ciphers would not communicate to the Hunchentoot server,
where as afterward, the Hunchentoot url worked fine.

Best Regards,

Kari Lentz


On Fri, Jan 31, 2014 at 10:43 AM, Anton Vodonosov <avodonosov at yandex.ru>wrote:

> Hi, thanks for the patch.
>
> Have you tested it? On what lisp/OS ?
>
> 31.01.2014, 19:19, "Kari Lentz" <kari.k.lentz at gmail.com>:
> > Please find attached a patch supports enables CL+SSL to support ciphers
> that require a temporary/ephemeral RSA key.  To quote the OpenSSL
> documentation:
> > "When using a cipher with RSA authentication, an ephemeral RSA key
> exchange can take place. In this case the session data are negotiated using
> the ephemeral/temporary RSA key and the RSA key supplied and certified by
> the certificate chain is only used for signing.
> >
> > Under previous export restrictions, ciphers with RSA keys shorter (512
> bits) than the usual key length of 1024 bits were created. To use these
> ciphers with RSA keys of usual length, an ephemeral key exchange must be
> performed, as the normal (certified) key cannot be directly used."
> > Basically, it accomplishes this by calling the Open SSL library
> function, "SSL_CTX_set_tmp_rsa_callback", upon initialization with a
> callback function whose purpose is to generate the ephemeral RSA key key.
> >
> > Best Regards,
> >
> > Kari Lentz
>
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