gnutls_priority_init — Sets priorities for the cipher suites supported by gnutls.
#include <gnutls/gnutls.h>
int
gnutls_priority_init( |
gnutls_priority_t * | priority_cache, |
| const char * | priorities, | |
| const char ** | err_pos); |
is a gnutls_prioritity_t structure.
is a string describing priorities
In case of an error this will have the position in the string the error occured
Sets priorities for the ciphers, key exchange methods,
macs and compression methods. This is to avoid using the
gnutls_*_priority()
functions.
The priorities
option allows you to specify a semi−colon separated
list of the cipher priorities to enable.
Unless the first keyword is "NONE" the defaults are:
"PERFORMANCE" all the "secure" ciphersuites are enabled, limited to 128 bit ciphers and sorted by terms of speed performance.
"NORMAL" option enables all "secure" ciphersuites. The 256−bit ciphers are included as a fallback only. The ciphers are sorted by security margin.
"SECURE128" flag enables all "secure" ciphersuites with ciphers up to 128 bits, sorted by security margin.
"SECURE256" flag enables all "secure" ciphersuites including the 256 bit ciphers, sorted by security margin.
"EXPORT" all the ciphersuites are enabled, including the low−security 40 bit ciphers.
"NONE" nothing is enabled. This disables even protocols and compression methods.
'!' or '−' appended with an algorithm will remove
this algorithm. '+' appended with an algorithm will add this
algorithm. 'COMPAT' will enable
compatibility features for a server.
To avoid collisions in order to specify a compression algorithm in this string you have to prefix it with "COMP−", protocol versions with "VERS−" and certificate types with "CTYPE−". All other algorithms don't need a prefix.
For key exchange algorithms when in NORMAL or SECURE levels the perfect forward secrecy algorithms take precendence of the other protocols. In all cases all the supported key exchange algorithms are enabled (except for the RSA−EXPORT which is only enabled in EXPORT level).
Note that although one can select very long key sizes (such as 256 bits) for symmetric algorithms, to actually increase security the public key algorithms have to use longer key sizes as well.
"NORMAL:!AES−128−CBC",
"EXPORT:!VERS−TLS1.0:+COMP−DEFLATE:+CTYPE−OPENPGP",
"NONE:+VERS−TLS1.0:+AES−128−CBC:+RSA:+SHA1:+COMP−NULL",
"NORMAL", "NORMAL:COMPAT".
On syntax error GNUTLS_E_INVALID_REQUEST is returned, GNUTLS_E_SUCCESS on success, or an error code.
The full documentation for gnutls is maintained as a Texinfo manual. If the info and gnutls programs are properly installed at your site, the command
info gnutls
should give you access to the complete manual.
| COPYRIGHT |
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Copyright © 2008 Free Software Foundation. Permission is granted to make and distribute verbatim copies of this manual provided the copyright notice and this permission notice are preserved on all copies. |