openssl/doc/ssl/SSL_CIPHER_get_name.pod
Dr. Stephen Henson 98c9ce2f55 SSL_CIPHER lookup functions.
Add tables to convert between SSL_CIPHER fields and indices for ciphers
and MACs.

Reorganise ssl_ciph.c to use tables to lookup values and load them.

New functions SSL_CIPHER_get_cipher_nid and SSL_CIPHER_get_digest_nid.

Add documentation.

Reviewed-by: Rich Salz <rsalz@openssl.org>
2015-04-22 15:00:53 +01:00

131 lines
4.3 KiB
Text

=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);
int SSL_CIPHER_get_cipher_nid(const SSL_CIPHER *c);
int SSL_CIPHER_get_digest_nid(const SSL_CIPHER *c);
=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<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.
SSL_CIPHER_get_cipher_nid() returns the cipher NID corresponding to B<c>.
If there is no cipher (e.g. for ciphersuites 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>. If there is no digest (e.g. for AEAD ciphersuites) then
B<NID_undef> 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<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():
DHE-RSA-DES-CBC3-SHA SSLv3 Kx=DH Au=RSA Enc=3DES(168) Mac=SHA1
DHE-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.
=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)>
=cut