gnutls_priority_t * priority_cache
is a gnutls_priority_t type.
const char * priorities
is a string describing priorities (may be NULL)
const char ** err_pos
In case of an error this will have the position in
the string the error occurred
zero or GNUTLS_PRIORITY_INIT_DEF_APPEND
Sets priorities for the ciphers, key exchange methods, and macs.
The priority_cache should be deinitialized using
The priorities option allows you to specify a colon separated
list of the cipher priorities to enable. Some keywords are
defined to provide quick access to common preferences.
When flags is set to GNUTLS_PRIORITY_INIT_DEF_APPEND then the
priorities specified will be appended to the default options.
Unless there is a special need, use the "NORMAL" keyword to apply
a reasonable security level, or "NORMAL:%COMPAT" for
"PERFORMANCE" means all the "secure" ciphersuites are enabled,
limited to 128 bit ciphers and sorted by terms of speed
"LEGACY" the NORMAL settings for GnuTLS 3.2.x or earlier. There
is no verification profile set, and the allowed DH primes are
considered weak today.
"NORMAL" means all "secure" ciphersuites. The 256-bit ciphers are
included as a fallback only. The ciphers are sorted by security
"PFS" means all "secure" ciphersuites that support perfect
forward secrecy. The 256-bit ciphers are included as a fallback
only. The ciphers are sorted by security margin.
"SECURE128" means all "secure" ciphersuites of security level
128-bit or more.
"SECURE192" means all "secure" ciphersuites of security level
192-bit or more.
"SUITEB128" means all the NSA SuiteB ciphersuites with security
level of 128.
"SUITEB192" means all the NSA SuiteB ciphersuites with security
level of 192.
"NONE" means nothing is enabled. This disables everything,
"@KEYWORD1,KEYWORD2,..." The system administrator imposed
settings. The provided keyword(s) will be expanded from a
configuration-time provided file - default is:
/etc/gnutls/config. Any attributes that follow it, will be
appended to the expanded string. If multiple keywords are
provided, separated by commas, then the first keyword that exists
in the configuration file will be used. At least one of the
keywords must exist, or this function will return an error.
Typical usage would be to specify an application specified
keyword first, followed by "SYSTEM" as a default fallback. e.g.,
" LIBVIRT ,SYSTEM:!-VERS-SSL3.0" will first try to find a config
file entry matching "LIBVIRT", but if that does not exist will
use the entry for "SYSTEM". If "SYSTEM" does not exist either, an
error will be returned. In all cases, the SSL3.0 protocol will be
disabled. The system priority file entries should be formatted as
"KEYWORD=VALUE", e.g., "SYSTEM=NORMAL:+ARCFOUR-128".
Special keywords are "!", "-" and "+". "!" or "-" appended with
an algorithm will remove this algorithm. "+" appended with an
algorithm will add this algorithm.
Check the GnuTLS manual section "Priority strings" for detailed
"NORMAL:+ARCFOUR-128" means normal ciphers plus ARCFOUR-128.
"SECURE128:-VERS-SSL3.0" means that only secure ciphers are and
enabled, SSL3.0 is disabled.
Note that "NORMAL:%COMPAT" is the most compatible mode.
A NULL priorities string indicates the default priorities to be
used (this is available since GnuTLS 3.3.0).
This page is part of the GnuTLS (GnuTLS Transport Layer Security
Library) project. Information about the project can be found at
⟨http://www.gnutls.org/⟩. If you have a bug report for this
manual page, send it to firstname.lastname@example.org. This page was obtained
from the tarball gnutls-3.7.1.tar.xz fetched from
⟨http://www.gnutls.org/download.html⟩ on 2021-04-01. If you
discover any rendering problems in this HTML version of the page,
or you believe there is a better or more up-to-date source for
the page, or you have corrections or improvements to the
information in this COLOPHON (which is not part of the original
manual page), send a mail to email@example.com
gnutls 3.7.1 gnutls_priority_init2(3)