=back
+If 0 is returned or B<*codes> is set to a nonzero value the supplied
+parameters should not be used for Diffie-Hellman operations otherwise
+the security properties of the key exchange are not guaranteed.
+
DH_check_ex(), DH_check_params() and DH_check_pub_key_ex() are similar to
DH_check() and DH_check_params() respectively, but the error reasons are added
to the thread's error queue instead of provided as return values from the