0ec6898c67
see RT #3203 Future versions of OpenSSL use the canonical terms "ECDHE" and "DHE" as configuration strings and compilation constants. This patch introduces aliases so that the stable 1.0.2 branch can be forward-compatible with code and configuration scripts that use the normalized terms, while avoiding changing any library output for stable users. Signed-off-by: Kurt Roeckx <kurt@roeckx.be> Reviewed-by: Matt Caswell <matt@openssl.org>
74 lines
2.9 KiB
Text
74 lines
2.9 KiB
Text
=pod
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=head1 NAME
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SSL_CTX_set_cipher_list, SSL_set_cipher_list - choose list of available SSL_CIPHERs
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=head1 SYNOPSIS
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#include <openssl/ssl.h>
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int SSL_CTX_set_cipher_list(SSL_CTX *ctx, const char *str);
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int SSL_set_cipher_list(SSL *ssl, const char *str);
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=head1 DESCRIPTION
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SSL_CTX_set_cipher_list() sets the list of available ciphers for B<ctx>
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using the control string B<str>. The format of the string is described
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in L<ciphers(1)|ciphers(1)>. The list of ciphers is inherited by all
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B<ssl> objects created from B<ctx>.
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SSL_set_cipher_list() sets the list of ciphers only for B<ssl>.
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=head1 NOTES
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The control string B<str> should be universally usable and not depend
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on details of the library configuration (ciphers compiled in). Thus no
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syntax checking takes place. Items that are not recognized, because the
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corresponding ciphers are not compiled in or because they are mistyped,
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are simply ignored. Failure is only flagged if no ciphers could be collected
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at all.
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It should be noted, that inclusion of a cipher to be used into the list is
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a necessary condition. On the client side, the inclusion into the list is
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also sufficient. On the server side, additional restrictions apply. All ciphers
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have additional requirements. ADH ciphers don't need a certificate, but
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DH-parameters must have been set. All other ciphers need a corresponding
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certificate and key.
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A RSA cipher can only be chosen, when a RSA certificate is available.
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RSA export ciphers with a keylength of 512 bits for the RSA key require
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a temporary 512 bit RSA key, as typically the supplied key has a length
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of 1024 bit (see
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L<SSL_CTX_set_tmp_rsa_callback(3)|SSL_CTX_set_tmp_rsa_callback(3)>).
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RSA ciphers using DHE need a certificate and key and additional DH-parameters
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(see L<SSL_CTX_set_tmp_dh_callback(3)|SSL_CTX_set_tmp_dh_callback(3)>).
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A DSA cipher can only be chosen, when a DSA certificate is available.
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DSA ciphers always use DH key exchange and therefore need DH-parameters
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(see L<SSL_CTX_set_tmp_dh_callback(3)|SSL_CTX_set_tmp_dh_callback(3)>).
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When these conditions are not met for any cipher in the list (e.g. a
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client only supports export RSA ciphers with a asymmetric key length
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of 512 bits and the server is not configured to use temporary RSA
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keys), the "no shared cipher" (SSL_R_NO_SHARED_CIPHER) error is generated
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and the handshake will fail.
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If the cipher list does not contain any SSLv2 cipher suites (this is the
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default) then SSLv2 is effectively disabled and neither clients nor servers
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will attempt to use SSLv2.
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=head1 RETURN VALUES
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SSL_CTX_set_cipher_list() and SSL_set_cipher_list() return 1 if any cipher
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could be selected and 0 on complete failure.
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=head1 SEE ALSO
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L<ssl(3)|ssl(3)>, L<SSL_get_ciphers(3)|SSL_get_ciphers(3)>,
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L<SSL_CTX_use_certificate(3)|SSL_CTX_use_certificate(3)>,
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L<SSL_CTX_set_tmp_rsa_callback(3)|SSL_CTX_set_tmp_rsa_callback(3)>,
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L<SSL_CTX_set_tmp_dh_callback(3)|SSL_CTX_set_tmp_dh_callback(3)>,
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L<ciphers(1)|ciphers(1)>
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=cut
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