It should be noted, that inclusion of a cipher to be used into the list is
a necessary condition. On the client side, the inclusion into the list is
-also sufficient. On the server side, additional restrictions apply. All ciphers
-have additional requirements. ADH ciphers don't need a certificate, but
-DH-parameters must have been set. All other ciphers need a corresponding
-certificate and key.
+also sufficient unless the security level excludes it. On the server side,
+additional restrictions apply. All ciphers have additional requirements.
+ADH ciphers don't need a certificate, but DH-parameters must have been set.
+All other ciphers need a corresponding certificate and key.
A RSA cipher can only be chosen, when a RSA certificate is available.
RSA export ciphers with a keylength of 512 bits for the RSA key require
a temporary 512 bit RSA key, as typically the supplied key has a length
-of 1024 bit. RSA ciphers using EDH need a certificate and key and
-additional DH-parameters.
+of 1024 bit (see
+L<SSL_CTX_set_tmp_rsa_callback(3)|SSL_CTX_set_tmp_rsa_callback(3)>).
+RSA ciphers using DHE need a certificate and key and additional DH-parameters
+(see L<SSL_CTX_set_tmp_dh_callback(3)|SSL_CTX_set_tmp_dh_callback(3)>).
A DSA cipher can only be chosen, when a DSA certificate is available.
-DSA ciphers always use DH key exchange and therefore need DH-parameters.
+DSA ciphers always use DH key exchange and therefore need DH-parameters
+(see L<SSL_CTX_set_tmp_dh_callback(3)|SSL_CTX_set_tmp_dh_callback(3)>).
When these conditions are not met for any cipher in the list (e.g. a
client only supports export RSA ciphers with a asymmetric key length
keys), the "no shared cipher" (SSL_R_NO_SHARED_CIPHER) error is generated
and the handshake will fail.
+If the cipher list does not contain any SSLv2 cipher suites (this is the
+default) then SSLv2 is effectively disabled and neither clients nor servers
+will attempt to use SSLv2.
+
=head1 RETURN VALUES
SSL_CTX_set_cipher_list() and SSL_set_cipher_list() return 1 if any cipher
L<ssl(3)|ssl(3)>, L<SSL_get_ciphers(3)|SSL_get_ciphers(3)>,
L<SSL_CTX_use_certificate(3)|SSL_CTX_use_certificate(3)>,
+L<SSL_CTX_set_tmp_rsa_callback(3)|SSL_CTX_set_tmp_rsa_callback(3)>,
+L<SSL_CTX_set_tmp_dh_callback(3)|SSL_CTX_set_tmp_dh_callback(3)>,
L<ciphers(1)|ciphers(1)>
=cut