gnutls_priority_init(3)

1gnutls_priority_init(3)             gnutls             gnutls_priority_init(3)
2
3
4

NAME

6       gnutls_priority_init - API function
7

SYNOPSIS

9       #include <gnutls/gnutls.h>
10
11       int gnutls_priority_init(gnutls_priority_t * priority_cache, const char
12       * priorities, const char ** err_pos);
13

ARGUMENTS

15       gnutls_priority_t * priority_cache
16                   is a gnutls_prioritity_t structure.
17
18       const char * priorities
19                   is a string describing priorities (may be NULL)
20
21       const char ** err_pos
22                   In case of an error this will  have  the  position  in  the
23                   string the error occurred
24

DESCRIPTION

26       Sets  priorities  for  the ciphers, key exchange methods, macs and com‐
27       pression methods.
28
29       The priorities option allows you to specify a colon separated  list  of
30       the  cipher priorities to enable.  Some keywords are defined to provide
31       quick access to common preferences.
32
33       Unless there is a special need, use the "NORMAL"  keyword  to  apply  a
34       reasonable security level, or "NORMAL:COMPAT" for compatibility.
35
36       "PERFORMANCE"  means all the "secure" ciphersuites are enabled, limited
37       to 128 bit ciphers and sorted by terms of speed performance.
38
39       "LEGACY" the NORMAL settings for GnuTLS 3.2.x or earlier. There  is  no
40       verification profile set, and the allowed DH primes are considered weak
41       today.
42
43       "NORMAL" means all  "secure"  ciphersuites.  The  256-bit  ciphers  are
44       included  as  a fallback only.  The ciphers are sorted by security mar‐
45       gin.
46
47       "PFS" means all "secure"  ciphersuites  that  support  perfect  forward
48       secrecy.   The  256-bit  ciphers  are included as a fallback only.  The
49       ciphers are sorted by security margin.
50
51       "SECURE128" means all "secure" ciphersuites of security  level  128-bit
52       or more.
53
54       "SECURE192"  means  all "secure" ciphersuites of security level 192-bit
55       or more.
56
57       "SUITEB128" means all the NSA SuiteB ciphersuites with  security  level
58       of 128.
59
60       "SUITEB192"  means  all the NSA SuiteB ciphersuites with security level
61       of 192.
62
63       "EXPORT" means all ciphersuites are enabled, including the low-security
64       40 bit ciphers.
65
66       "NONE" means nothing is enabled.  This disables even protocols and com‐
67       pression methods.
68
69       " KEYWORD " The system administrator  imposed  settings.  The  provided
70       keywords  will  be  expanded  from a configuration-time provided file -
71       default is: /etc/gnutls/default-priorities. Any  keywords  that  follow
72       it,  will  be  appended  to  the expanded string. If there is no system
73       string, then the function will fail. The system file should be  format‐
74       ted as "KEYWORD=VALUE", e.g., "SYSTEM=NORMAL:-ARCFOUR-128".
75
76       Special  keywords  are  "!",  "-" and "+".  "!" or "-" appended with an
77       algorithm will remove this algorithm.  "+" appended with  an  algorithm
78       will add this algorithm.
79
80       Check  the GnuTLS manual section "Priority strings" for detailed infor‐
81       mation.
82

EXAMPLES

84       "NONE:+VERS-TLS-ALL:+MAC-ALL:+RSA:+AES-128-CBC:+SIGN-ALL:+COMP-NULL"
85
86       "NORMAL:-ARCFOUR-128" means normal ciphers except for ARCFOUR-128.
87
88       "SECURE128:-VERS-SSL3.0:+COMP-DEFLATE" means that only  secure  ciphers
89       are enabled, SSL3.0 is disabled, and libz compression enabled.
90
91       "NONE:+VERS-TLS-ALL:+AES-128-CBC:+RSA:+SHA1:+COMP-NULL:+SIGN-RSA-SHA1",
92
93       "NONE:+VERS-TLS-ALL:+AES-128-CBC:+ECDHE-RSA:+SHA1:+COMP-NULL:+SIGN-RSA-SHA1:+CURVE-SECP256R1",
94
95       "SECURE256:+SECURE128",
96
97       Note that "NORMAL:COMPAT" is the most compatible mode.
98
99       A NULL  priorities string indicates the default priorities to  be  used
100       (this is available since GnuTLS 3.3.0).
101

RETURNS

103       On  syntax error GNUTLS_E_INVALID_REQUEST is returned, GNUTLS_E_SUCCESS
104       on success, or an error code.
105

REPORTING BUGS

107       Report bugs to <bugs@gnutls.org>.
108       Home page: http://www.gnutls.org
109
110

COPYRIGHT

112       Copyright © 2001-2014 Free Software Foundation, Inc..
113       Copying and distribution of this file, with  or  without  modification,
114       are  permitted  in  any  medium  without royalty provided the copyright
115       notice and this notice are preserved.
116