NAME

SSL_CIPHER_get_name, SSL_CIPHER_standard_name, OPENSSL_cipher_name, SSL_CIPHER_get_bits, SSL_CIPHER_get_version, SSL_CIPHER_description, SSL_CIPHER_get_cipher_nid, SSL_CIPHER_get_digest_nid, SSL_CIPHER_get_handshake_digest, SSL_CIPHER_get_kx_nid, SSL_CIPHER_get_auth_nid, SSL_CIPHER_is_aead, SSL_CIPHER_find, SSL_CIPHER_get_id, SSL_CIPHER_get_protocol_id - get SSL_CIPHER properties


SYNOPSIS

 #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);
 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);


DESCRIPTION

SSL_CIPHER_get_name() returns a pointer to the name of cipher. If the cipher is NULL, it returns ``(NONE)''.

SSL_CIPHER_standard_name() returns a pointer to the standard RFC name of cipher. If the cipher is NULL, it returns ``(NONE)''. If the cipher has no standard name, it returns NULL. If cipher was defined in both SSLv3 and TLS, it returns the TLS name.

OPENSSL_cipher_name() returns a pointer to the OpenSSL name of stdname. If the stdname is NULL, or stdname has no corresponding OpenSSL name, it returns ``(NONE)''. Where both exist, stdname should be the TLS name rather than the SSLv3 name.

SSL_CIPHER_get_bits() returns the number of secret bits used for cipher. If 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 cipher is NULL.

SSL_CIPHER_get_cipher_nid() returns the cipher NID corresponding to c. If there is no cipher (e.g. for cipher suites with no encryption) then NID_undef is returned.

SSL_CIPHER_get_digest_nid() returns the digest NID corresponding to the MAC used by c during record encryption/decryption. If there is no digest (e.g. for AEAD cipher suites) then 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 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 c. If there is no key exchange, then NID_undef is returned. If any appropriate key exchange algorithm can be used (as in the case of TLS 1.3 cipher suites) NID_kx_any is returned. Examples (not comprehensive):

 NID_kx_rsa
 NID_kx_ecdhe
 NID_kx_dhe
 NID_kx_psk

SSL_CIPHER_get_auth_nid() returns the authentication NID corresponding to the method used by c. If there is no authentication, then NID_undef is returned. If any appropriate authentication algorithm can be used (as in the case of TLS 1.3 cipher suites) NID_auth_any is returned. Examples (not comprehensive):

 NID_auth_rsa
 NID_auth_ecdsa
 NID_auth_psk

SSL_CIPHER_is_aead() returns 1 if the cipher c is AEAD (e.g. GCM or ChaCha20/Poly1305), and 0 if it is not AEAD.

SSL_CIPHER_find() returns a SSL_CIPHER structure which has the cipher ID stored in ptr. The ptr parameter is a two element array of 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 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 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 c.

SSL_CIPHER_description() returns a textual description of the cipher used into the buffer buf of length len provided. If 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, NULL is returned.

The string returned by SSL_CIPHER_description() consists of several fields separated by whitespace:

<ciphername>

Textual representation of the cipher name.

<protocol version>

Protocol version, such as TLSv1.2, when the cipher was first defined.

Kx=<key exchange>

Key exchange method such as RSA, ECDHE, etc.

Au=<authentication>

Authentication method such as RSA, None, etc.. None is the representation of anonymous ciphers.

Enc=<symmetric encryption method>

Encryption method, with number of secret bits, such as AESGCM(128).

Mac=<message authentication code>

Message digest, such as SHA256.

Some examples for the output of SSL_CIPHER_description():

 ECDHE-RSA-AES256-GCM-SHA256 TLSv1.2 Kx=ECDH     Au=RSA  Enc=AESGCM(256) Mac=AEAD
 RSA-PSK-AES256-CBC-SHA384 TLSv1.0 Kx=RSAPSK   Au=RSA  Enc=AES(256)  Mac=SHA384


RETURN VALUES

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 null-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 NID_undef if an error occurred.

SSL_CIPHER_get_handshake_digest() returns a valid 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 SSL_CIPHER structure or NULL if an error occurred.

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.


HISTORY

SSL_CIPHER_get_version() was updated to always return the correct protocol string in OpenSSL 1.1.0.

SSL_CIPHER_description() was changed to return NULL on error, rather than a fixed string, in OpenSSL 1.1.0.

SSL_CIPHER_get_handshake_digest() was added in OpenSSL 1.1.1.

SSL_CIPHER_standard_name() was globally available in OpenSSL 1.1.1. Before OpenSSL 1.1.1, tracing (enable-ssl-trace argument to Configure) was required to enable this function.

OPENSSL_cipher_name() was added in OpenSSL 1.1.1.


SEE ALSO

ssl(7), SSL_get_current_cipher(3), SSL_get_ciphers(3), ciphers(1)


COPYRIGHT

Copyright 2000-2018 The OpenSSL Project Authors. All Rights Reserved.

Licensed under the OpenSSL license (the ``License''). You may not use this file except in compliance with the License. You can obtain a copy in the file LICENSE in the source distribution or at https://www.openssl.org/source/license.html.