@deftypefun {int} {gnutls_dh_get_prime_bits} (gnutls_session_t @var{session})

@var{session}: is a gnutls session

This function will return the bits of the prime used in the last

Diffie-Hellman key exchange with the peer.  Should be used for both

anonymous and ephemeral Diffie-Hellman.  Note that some ciphers,

like RSA and DSA without DHE, do not use a Diffie-Hellman key

exchange, and then this function will return 0.

@strong{Returns:} The Diffie-Hellman bit strength is returned, or 0 if no

Diffie-Hellman key exchange was done, or a negative error code on

failure.

@end deftypefun