SSL_CTX_SET_CIPHER_LIST(3) OpenSSL SSL_CTX_SET_CIPHER_LIST(3)
SSL_CTX_set_cipher_list, SSL_set_cipher_list - choose list
of available SSL_CIPHERs
#include <openssl/ssl.h>
int SSL_CTX_set_cipher_list(SSL_CTX *ctx, const char *str);
int SSL_set_cipher_list(SSL *ssl, const char *str);
SSL_CTX_set_cipher_list() sets the list of available ciphers
for ctx using the control string str. The format of the
string is described in ciphers(1). The list of ciphers is
inherited by all ssl objects created from ctx.
SSL_set_cipher_list() sets the list of ciphers only for ssl.
The control string str should be universally usable and not
depend on details of the library configuration (ciphers com-
piled in). Thus no syntax checking takes place. Items that
are not recognized, because the corresponding ciphers are
not compiled in or because they are mistyped, are simply
ignored. Failure is only flagged if no ciphers could be col-
lected at all.
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 certifi-
cate, 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 typ-
ically the supplied key has a length of 1024 bit (see
SSL_CTX_set_tmp_rsa_callback(3)). RSA ciphers using EDH need
a certificate and key and additional DH-parameters (see
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 there-
fore need DH-parameters (see
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 asym-
metric key length of 512 bits and the server is not config-
ured to use temporary RSA keys), the "no shared cipher"
MirOS BSD #10-current 2005-02-05 1
SSL_CTX_SET_CIPHER_LIST(3) OpenSSL SSL_CTX_SET_CIPHER_LIST(3)
(SSL_R_NO_SHARED_CIPHER) error is generated and the
handshake will fail.
SSL_CTX_set_cipher_list() and SSL_set_cipher_list() return 1
if any cipher could be selected and 0 on complete failure.
ssl(3), SSL_get_ciphers(3), SSL_CTX_use_certificate(3),
SSL_CTX_set_tmp_rsa_callback(3),
SSL_CTX_set_tmp_dh_callback(3), ciphers(1)
MirOS BSD #10-current 2005-02-05 2
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