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=head1 NAME
- get SSL_CIPHER properties
#include <openssl/ssl.h>
const char *SSL_CIPHER_get_name(const SSL_CIPHER *cipher);
const char *SSL_CIPHER_standard_name(const SSL_CIPHER *cipher);
const char *OPENSSL_cipher_name(const char *stdname);
int SSL_CIPHER_get_bits(const SSL_CIPHER *cipher, int *alg_bits);
const char *SSL_CIPHER_get_version(const SSL_CIPHER *cipher);
char *SSL_CIPHER_description(const SSL_CIPHER *cipher, char *buf, int size);
int SSL_CIPHER_get_cipher_nid(const SSL_CIPHER *c);
int SSL_CIPHER_get_digest_nid(const SSL_CIPHER *c);
const EVP_MD *SSL_CIPHER_get_handshake_digest(const SSL_CIPHER *c);
int SSL_CIPHER_get_kx_nid(const SSL_CIPHER *c);
int SSL_CIPHER_get_auth_nid(const SSL_CIPHER *c);
int SSL_CIPHER_is_aead(const SSL_CIPHER *c);
const SSL_CIPHER *SSL_CIPHER_find(SSL *ssl, const unsigned char *ptr);
uint32_t SSL_CIPHER_get_id(const SSL_CIPHER *c);
uint32_t SSL_CIPHER_get_protocol_id(const SSL_CIPHER *c);
SSL_CIPHER_get_name() returns a pointer to the name of B<cipher>. If the
B<cipher> is NULL, it returns "(NONE)".
SSL_CIPHER_standard_name() returns a pointer to the standard RFC name of
B<cipher>. If the B<cipher> is NULL, it returns "(NONE)". If the B<cipher>
has no standard name, it returns B<NULL>. If B<cipher> was defined in both
SSLv3 and TLS, it returns the TLS name.
OPENSSL_cipher_name() returns a pointer to the OpenSSL name of B<stdname>.
If the B<stdname> is NULL, or B<stdname> has no corresponding OpenSSL name,
it returns "(NONE)". Where both exist, B<stdname> should be the TLS name rather
than the SSLv3 name.
SSL_CIPHER_get_bits() returns the number of secret bits used for B<cipher>.
If B<cipher> is NULL, 0 is returned.
SSL_CIPHER_get_version() returns string which indicates the SSL/TLS protocol
version that first defined the cipher. It returns "(NONE)" if B<cipher> is NULL.
SSL_CIPHER_get_cipher_nid() returns the cipher NID corresponding to B<c>.
If there is no cipher (e.g. for cipher suites with no encryption) then
B<NID_undef> is returned.
SSL_CIPHER_get_digest_nid() returns the digest NID corresponding to the MAC
used by B<c> during record encryption/decryption. If there is no digest (e.g.
for AEAD cipher suites) then B<NID_undef> is returned.
SSL_CIPHER_get_handshake_digest() returns an EVP_MD for the digest used during
the SSL/TLS handshake when using the SSL_CIPHER B<c>. Note that this may be
different to the digest used to calculate the MAC for encrypted records.
SSL_CIPHER_get_kx_nid() returns the key exchange NID corresponding to the method
used by B<c>. If there is no key exchange, then B<NID_undef> is returned.
If any appropriate key exchange algorithm can be used (as in the case of TLS 1.3
cipher suites) B<NID_kx_any> is returned. Examples (not comprehensive):
SSL_CIPHER_get_auth_nid() returns the authentication NID corresponding to the method
used by B<c>. If there is no authentication, then B<NID_undef> is returned.
If any appropriate authentication algorithm can be used (as in the case of
TLS 1.3 cipher suites) B<NID_auth_any> is returned. Examples (not comprehensive):
SSL_CIPHER_is_aead() returns 1 if the cipher B<c> is AEAD (e.g. GCM or
ChaCha20/Poly1305), and 0 if it is not AEAD.
SSL_CIPHER_find() returns a B<SSL_CIPHER> structure which has the cipher ID stored
in B<ptr>. The B<ptr> parameter is a two element array of B<char>, which stores the
two-byte TLS cipher ID (as allocated by IANA) in network byte order. This parameter
is usually retrieved from a TLS packet by using functions like
L<SSL_client_hello_get0_ciphers(3)>. SSL_CIPHER_find() returns NULL if an
error occurs or the indicated cipher is not found.
SSL_CIPHER_get_id() returns the OpenSSL-specific ID of the given cipher B<c>. That ID is
not the same as the IANA-specific ID.
SSL_CIPHER_get_protocol_id() returns the two-byte ID used in the TLS protocol of the given
cipher B<c>.
SSL_CIPHER_description() returns a textual description of the cipher used
into the buffer B<buf> of length B<len> provided. If B<buf> is provided, it
must be at least 128 bytes, otherwise a buffer will be allocated using
OPENSSL_malloc(). If the provided buffer is too small, or the allocation fails,
B<NULL> is returned.
The string returned by SSL_CIPHER_description() consists of several fields
separated by whitespace:
=over 4
=item <ciphername>
Textual representation of the cipher name.
=item <protocol version>
The minimum protocol version that the ciphersuite supports, such as B<TLSv1.2>.
Note that this is not always the same as the protocol version in which the
ciphersuite was first defined because some ciphersuites are backwards compatible
with earlier protocol versions.
=item Kx=<key exchange>
Key exchange method such as B<RSA>, B<ECDHE>, etc.
=item Au=<authentication>
Authentication method such as B<RSA>, B<None>, etc.. None is the
representation of anonymous ciphers.
=item Enc=<symmetric encryption method>
Encryption method, with number of secret bits, such as B<AESGCM(128)>.
=item Mac=<message authentication code>
Message digest, such as B<SHA256>.
Some examples for the output of SSL_CIPHER_description():
RSA-PSK-AES256-CBC-SHA384 TLSv1.0 Kx=RSAPSK Au=RSA Enc=AES(256) Mac=SHA384
SSL_CIPHER_get_name(), SSL_CIPHER_standard_name(), OPENSSL_cipher_name(),
SSL_CIPHER_get_version() and SSL_CIPHER_description() return the corresponding
value in a NUL-terminated string for a specific cipher or "(NONE)"
if the cipher is not found.
SSL_CIPHER_get_bits() returns a positive integer representing the number of
secret bits or 0 if an error occurred.
SSL_CIPHER_get_cipher_nid(), SSL_CIPHER_get_digest_nid(),
SSL_CIPHER_get_kx_nid() and SSL_CIPHER_get_auth_nid() return the NID value or
B<NID_undef> if an error occurred.
SSL_CIPHER_get_handshake_digest() returns a valid B<EVP_MD> structure or NULL
if an error occurred.
SSL_CIPHER_is_aead() returns 1 if the cipher is AEAD or 0 otherwise.
SSL_CIPHER_find() returns a valid B<SSL_CIPHER> structure or NULL if an error
SSL_CIPHER_get_id() returns a 4-byte integer representing the OpenSSL-specific ID.
SSL_CIPHER_get_protocol_id() returns a 2-byte integer representing the TLS
protocol-specific ID.
=head1 SEE ALSO
L<ssl(7)>, L<SSL_get_current_cipher(3)>,
L<SSL_get_ciphers(3)>, L<openssl-ciphers(1)>
=head1 HISTORY
The SSL_CIPHER_get_version() function was updated to always return the
correct protocol string in OpenSSL 1.1.0.
The SSL_CIPHER_description() function was changed to return B<NULL> on error,
rather than a fixed string, in OpenSSL 1.1.0.
The SSL_CIPHER_get_handshake_digest() function was added in OpenSSL 1.1.1.
The SSL_CIPHER_standard_name() function was globally available in OpenSSL 1.1.1.
Before OpenSSL 1.1.1, tracing (B<enable-ssl-trace> argument to Configure) was
required to enable this function.
The OPENSSL_cipher_name() function was added in OpenSSL 1.1.1.
Copyright 2000-2019 The OpenSSL Project Authors. All Rights Reserved.
Licensed under the Apache License 2.0 (the "License"). You may not use
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