/xlv3/openssl/0.9.7e-sgipl1/work/0.9.7e-sgipl1/openssl-
0.9.7e/doc/ssl
Page 1 (printed 10/20/05)
SSL_CTX_set_cipher_list23/Jul/2001 (0.9SSL_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);
DESCRIPTION
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.
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
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SSL_CTX_set_cipher_list23/Jul/2001 (0.9SSL_CTX_set_cipher_list(3)
configured to use temporary RSA keys), the "no shared
cipher" (SSL_R_NO_SHARED_CIPHER) error is generated and the
handshake will fail.
RETURN VALUES
SSL_CTX_set_cipher_list() and SSL_set_cipher_list() return 1
if any cipher could be selected and 0 on complete failure.
SEE ALSO
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)
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