1=pod 2 3=head1 NAME 4 5SSL_CTX_set_cipher_list, 6SSL_set_cipher_list, 7SSL_CTX_set_ciphersuites, 8SSL_set_ciphersuites, 9OSSL_default_cipher_list, 10OSSL_default_ciphersuites 11- choose list of available SSL_CIPHERs 12 13=head1 SYNOPSIS 14 15 #include <openssl/ssl.h> 16 17 int SSL_CTX_set_cipher_list(SSL_CTX *ctx, const char *str); 18 int SSL_set_cipher_list(SSL *ssl, const char *str); 19 20 int SSL_CTX_set_ciphersuites(SSL_CTX *ctx, const char *str); 21 int SSL_set_ciphersuites(SSL *s, const char *str); 22 23 const char *OSSL_default_cipher_list(void); 24 const char *OSSL_default_ciphersuites(void); 25 26=head1 DESCRIPTION 27 28SSL_CTX_set_cipher_list() sets the list of available ciphers (TLSv1.2 and below) 29for B<ctx> using the control string B<str>. The format of the string is described 30in L<openssl-ciphers(1)>. The list of ciphers is inherited by all 31B<ssl> objects created from B<ctx>. This function does not impact TLSv1.3 32ciphersuites. Use SSL_CTX_set_ciphersuites() to configure those. 33 34SSL_set_cipher_list() sets the list of ciphers (TLSv1.2 and below) only for 35B<ssl>. 36 37SSL_CTX_set_ciphersuites() is used to configure the available TLSv1.3 38ciphersuites for B<ctx>. This is a simple colon (":") separated list of TLSv1.3 39ciphersuite names in order of preference. Valid TLSv1.3 ciphersuite names are: 40 41=over 4 42 43=item TLS_AES_128_GCM_SHA256 44 45=item TLS_AES_256_GCM_SHA384 46 47=item TLS_CHACHA20_POLY1305_SHA256 48 49=item TLS_AES_128_CCM_SHA256 50 51=item TLS_AES_128_CCM_8_SHA256 52 53=back 54 55An empty list is permissible. The default value for the this setting is: 56 57"TLS_AES_256_GCM_SHA384:TLS_CHACHA20_POLY1305_SHA256:TLS_AES_128_GCM_SHA256" 58 59SSL_set_ciphersuites() is the same as SSL_CTX_set_ciphersuites() except it 60configures the ciphersuites for B<ssl>. 61 62OSSL_default_cipher_list() returns the default cipher string for TLSv1.2 63(and earlier) ciphers. OSSL_default_ciphersuites() returns the default 64cipher string for TLSv1.3 ciphersuites. 65 66=head1 NOTES 67 68The control string B<str> for SSL_CTX_set_cipher_list(), SSL_set_cipher_list(), 69SSL_CTX_set_ciphersuites() and SSL_set_ciphersuites() should be universally 70usable and not depend on details of the library configuration (ciphers compiled 71in). Thus no syntax checking takes place. Items that are not recognized, because 72the corresponding ciphers are not compiled in or because they are mistyped, 73are simply ignored. Failure is only flagged if no ciphers could be collected 74at all. 75 76It should be noted, that inclusion of a cipher to be used into the list is 77a necessary condition. On the client side, the inclusion into the list is 78also sufficient unless the security level excludes it. On the server side, 79additional restrictions apply. All ciphers have additional requirements. 80ADH ciphers don't need a certificate, but DH-parameters must have been set. 81All other ciphers need a corresponding certificate and key. 82 83An RSA cipher can only be chosen, when an RSA certificate is available. 84RSA ciphers using DHE need a certificate and key and additional DH-parameters 85(see L<SSL_CTX_set_tmp_dh_callback(3)>). 86 87A DSA cipher can only be chosen, when a DSA certificate is available. 88DSA ciphers always use DH key exchange and therefore need DH-parameters 89(see L<SSL_CTX_set_tmp_dh_callback(3)>). 90 91When these conditions are not met for any cipher in the list (e.g. a 92client only supports export RSA ciphers with an asymmetric key length 93of 512 bits and the server is not configured to use temporary RSA 94keys), the "no shared cipher" (SSL_R_NO_SHARED_CIPHER) error is generated 95and the handshake will fail. 96 97OSSL_default_cipher_list() and OSSL_default_ciphersuites() replace 98SSL_DEFAULT_CIPHER_LIST and TLS_DEFAULT_CIPHERSUITES, respectively. The 99cipher list defines are deprecated as of 3.0. 100 101=head1 RETURN VALUES 102 103SSL_CTX_set_cipher_list() and SSL_set_cipher_list() return 1 if any cipher 104could be selected and 0 on complete failure. 105 106SSL_CTX_set_ciphersuites() and SSL_set_ciphersuites() return 1 if the requested 107ciphersuite list was configured, and 0 otherwise. 108 109=head1 SEE ALSO 110 111L<ssl(7)>, L<SSL_get_ciphers(3)>, 112L<SSL_CTX_use_certificate(3)>, 113L<SSL_CTX_set_tmp_dh_callback(3)>, 114L<openssl-ciphers(1)> 115 116=head1 HISTORY 117 118OSSL_default_cipher_list() and OSSL_default_ciphersites() are new in 3.0. 119 120=head1 COPYRIGHT 121 122Copyright 2000-2021 The OpenSSL Project Authors. All Rights Reserved. 123 124Licensed under the Apache License 2.0 (the "License"). You may not use 125this file except in compliance with the License. You can obtain a copy 126in the file LICENSE in the source distribution or at 127L<https://www.openssl.org/source/license.html>. 128 129=cut 130