SSL_CTX_set_cipher_list(3) OpenSSL SSL_CTX_set_cipher_list(3)NAME
SSL_CTX_set_cipher_list, SSL_set_cipher_list - choose list
of available SSL_CIPHERs
SYNOPSIS
#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);
DESCRIPTIONSSL_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.
NOTES
The control string str should be universally usable and
not depend on details of the library configuration
(ciphers compiled 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 collected 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 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
(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
therefore 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 asymmetric key length of 512 bits and the server is not
configured to use temporary RSA keys), the "no shared
cipher" (SSL_R_NO_SHARED_CIPHER) error is generated and
the handshake will fail.
RETURN VALUESSSL_CTX_set_cipher_list() and SSL_set_cipher_list() return
1 if any cipher could be selected and 0 on complete
failure.
SEE ALSOssl(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)23/Jul/2001 0.9.6j SSL_CTX_set_cipher_list(3)
