1=pod 2 3=head1 NAME 4 5SSL_CTX_set_cipher_list, SSL_set_cipher_list - choose list of available SSL_CIPHERs 6 7=head1 SYNOPSIS 8 9 #include <openssl/ssl.h> 10 11 int SSL_CTX_set_cipher_list(SSL_CTX *ctx, const char *str); 12 int SSL_set_cipher_list(SSL *ssl, const char *str); 13 14=head1 DESCRIPTION 15 16SSL_CTX_set_cipher_list() sets the list of available ciphers for B<ctx> 17using the control string B<str>. The format of the string is described 18in L<ciphers(1)|ciphers(1)>. The list of ciphers is inherited by all 19B<ssl> objects created from B<ctx>. 20 21SSL_set_cipher_list() sets the list of ciphers only for B<ssl>. 22 23=head1 NOTES 24 25The control string B<str> should be universally usable and not depend 26on details of the library configuration (ciphers compiled in). Thus no 27syntax checking takes place. Items that are not recognized, because the 28corresponding ciphers are not compiled in or because they are mistyped, 29are simply ignored. Failure is only flagged if no ciphers could be collected 30at all. 31 32It should be noted, that inclusion of a cipher to be used into the list is 33a necessary condition. On the client side, the inclusion into the list is 34also sufficient. On the server side, additional restrictions apply. All ciphers 35have additional requirements. ADH ciphers don't need a certificate, but 36DH-parameters must have been set. All other ciphers need a corresponding 37certificate and key. 38 39A RSA cipher can only be chosen, when a RSA certificate is available. 40RSA export ciphers with a keylength of 512 bits for the RSA key require 41a temporary 512 bit RSA key, as typically the supplied key has a length 42of 1024 bit (see 43L<SSL_CTX_set_tmp_rsa_callback(3)|SSL_CTX_set_tmp_rsa_callback(3)>). 44RSA ciphers using EDH need a certificate and key and additional DH-parameters 45(see L<SSL_CTX_set_tmp_dh_callback(3)|SSL_CTX_set_tmp_dh_callback(3)>). 46 47A DSA cipher can only be chosen, when a DSA certificate is available. 48DSA ciphers always use DH key exchange and therefore need DH-parameters 49(see L<SSL_CTX_set_tmp_dh_callback(3)|SSL_CTX_set_tmp_dh_callback(3)>). 50 51When these conditions are not met for any cipher in the list (e.g. a 52client only supports export RSA ciphers with a asymmetric key length 53of 512 bits and the server is not configured to use temporary RSA 54keys), the "no shared cipher" (SSL_R_NO_SHARED_CIPHER) error is generated 55and the handshake will fail. 56 57=head1 RETURN VALUES 58 59SSL_CTX_set_cipher_list() and SSL_set_cipher_list() return 1 if any cipher 60could be selected and 0 on complete failure. 61 62=head1 SEE ALSO 63 64L<ssl(3)|ssl(3)>, L<SSL_get_ciphers(3)|SSL_get_ciphers(3)>, 65L<SSL_CTX_use_certificate(3)|SSL_CTX_use_certificate(3)>, 66L<SSL_CTX_set_tmp_rsa_callback(3)|SSL_CTX_set_tmp_rsa_callback(3)>, 67L<SSL_CTX_set_tmp_dh_callback(3)|SSL_CTX_set_tmp_dh_callback(3)>, 68L<ciphers(1)|ciphers(1)> 69 70=cut 71