=pod

=head1 NAME

SSL_CIPHER_get_name, SSL_CIPHER_get_bits, SSL_CIPHER_get_version, SSL_CIPHER_description - get SSL_CIPHER properties

=head1 SYNOPSIS

 #include <openssl/ssl.h>

 const char *SSL_CIPHER_get_name(const SSL_CIPHER *cipher);
 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);

=head1 DESCRIPTION

SSL_CIPHER_get_name() returns a pointer to the name of B<cipher>. If the
argument is the NULL pointer, a pointer to the constant value "NONE" is
returned.

SSL_CIPHER_get_bits() returns the number of secret bits used for B<cipher>. If
B<alg_bits> is not NULL, it contains the number of bits processed by the
chosen algorithm. 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.
This is currently B<SSLv2> or B<TLSv1/SSLv3>.
In some cases it should possibly return "TLSv1.2" but does not;
use SSL_CIPHER_description() instead.
If B<cipher> is NULL, "(NONE)" is returned.

SSL_CIPHER_description() returns a textual description of the cipher used
into the buffer B<buf> of length B<len> provided. B<len> must be at least
128 bytes, otherwise a pointer to the string "Buffer too small" is
returned. If B<buf> is NULL, a buffer of 128 bytes is allocated using
OPENSSL_malloc(). If the allocation fails, a pointer to the string
"OPENSSL_malloc Error" is returned.

=head1 NOTES

The number of bits processed can be different from the secret bits. An
export cipher like e.g. EXP-RC4-MD5 has only 40 secret bits. The algorithm
does use the full 128 bits (which would be returned for B<alg_bits>), of
which however 88bits are fixed. The search space is hence only 40 bits.

The string returned by SSL_CIPHER_description() in case of success consists
of cleartext information separated by one or more blanks in the following
sequence:

=over 4

=item <ciphername>

Textual representation of the cipher name.

=item <protocol version>

Protocol version: B<SSLv2>, B<SSLv3>, B<TLSv1.2>. The TLSv1.0 ciphers are
flagged with SSLv3. No new ciphers were added by TLSv1.1.

=item Kx=<key exchange>

Key exchange method: B<RSA> (for export ciphers as B<RSA(512)> or
B<RSA(1024)>), B<DH> (for export ciphers as B<DH(512)> or B<DH(1024)>),
B<DH/RSA>, B<DH/DSS>, B<Fortezza>.

=item Au=<authentication>

Authentication method: B<RSA>, B<DSS>, B<DH>, B<None>. None is the
representation of anonymous ciphers.

=item Enc=<symmetric encryption method>

Encryption method with number of secret bits: B<DES(40)>, B<DES(56)>,
B<3DES(168)>, B<RC4(40)>, B<RC4(56)>, B<RC4(64)>, B<RC4(128)>,
B<RC2(40)>, B<RC2(56)>, B<RC2(128)>, B<IDEA(128)>, B<Fortezza>, B<None>.

=item Mac=<message authentication code>

Message digest: B<MD5>, B<SHA1>.

=item <export flag>

If the cipher is flagged exportable with respect to old US crypto
regulations, the word "B<export>" is printed.

=back

=head1 EXAMPLES

Some examples for the output of SSL_CIPHER_description():

 EDH-RSA-DES-CBC3-SHA    SSLv3 Kx=DH       Au=RSA  Enc=3DES(168) Mac=SHA1
 EDH-DSS-DES-CBC3-SHA    SSLv3 Kx=DH       Au=DSS  Enc=3DES(168) Mac=SHA1
 RC4-MD5                 SSLv3 Kx=RSA      Au=RSA  Enc=RC4(128)  Mac=MD5
 EXP-RC4-MD5             SSLv3 Kx=RSA(512) Au=RSA  Enc=RC4(40)   Mac=MD5  export

A comp[lete list can be retrieved by invoking the following command:

 openssl ciphers -v ALL

=head1 BUGS

If SSL_CIPHER_description() is called with B<cipher> being NULL, the
library crashes.

If SSL_CIPHER_description() cannot handle a built-in cipher, the according
description of the cipher property is B<unknown>. This case should not
occur.

The standard terminology for ephemeral Diffie-Hellman schemes is DHE
(finite field) or ECDHE (elliptic curve).  This version of OpenSSL
idiosyncratically reports these schemes as EDH and EECDH, even though
it also accepts the standard terminology.

It is recommended to use the standard terminology (DHE and ECDHE)
during configuration (e.g. via SSL_CTX_set_cipher_list) for clarity of
configuration.  OpenSSL versions after 1.0.2 will report the standard
terms via SSL_CIPHER_get_name and SSL_CIPHER_description.

=head1 RETURN VALUES

See DESCRIPTION

=head1 SEE ALSO

L<ssl(3)|ssl(3)>, L<SSL_get_current_cipher(3)|SSL_get_current_cipher(3)>,
L<SSL_get_ciphers(3)|SSL_get_ciphers(3)>, L<ciphers(1)|ciphers(1)>,
L<SSL_CTX_set_cipher_list(3)|SSL_CTX_set_cipher_list(3)>

=cut
