1=pod
2
3=head1 NAME
4
5SSL_CTX_set1_groups, SSL_CTX_set1_groups_list, SSL_set1_groups,
6SSL_set1_groups_list, SSL_get1_groups, SSL_get_shared_group,
7SSL_CTX_set1_curves, SSL_CTX_set1_curves_list, SSL_set1_curves,
8SSL_set1_curves_list, SSL_get1_curves, SSL_get_shared_curve
9- EC supported curve functions
10
11=head1 SYNOPSIS
12
13 #include <openssl/ssl.h>
14
15 int SSL_CTX_set1_groups(SSL_CTX *ctx, int *glist, int glistlen);
16 int SSL_CTX_set1_groups_list(SSL_CTX *ctx, char *list);
17
18 int SSL_set1_groups(SSL *ssl, int *glist, int glistlen);
19 int SSL_set1_groups_list(SSL *ssl, char *list);
20
21 int SSL_get1_groups(SSL *ssl, int *groups);
22 int SSL_get_shared_group(SSL *s, int n);
23
24 int SSL_CTX_set1_curves(SSL_CTX *ctx, int *clist, int clistlen);
25 int SSL_CTX_set1_curves_list(SSL_CTX *ctx, char *list);
26
27 int SSL_set1_curves(SSL *ssl, int *clist, int clistlen);
28 int SSL_set1_curves_list(SSL *ssl, char *list);
29
30 int SSL_get1_curves(SSL *ssl, int *curves);
31 int SSL_get_shared_curve(SSL *s, int n);
32
33=head1 DESCRIPTION
34
35For all of the functions below that set the supported groups there must be at
36least one group in the list.
37
38SSL_CTX_set1_groups() sets the supported groups for B<ctx> to B<glistlen>
39groups in the array B<glist>. The array consist of all NIDs of groups in
40preference order. For a TLS client the groups are used directly in the
41supported groups extension. For a TLS server the groups are used to
42determine the set of shared groups.
43
44SSL_CTX_set1_groups_list() sets the supported groups for B<ctx> to
45string B<list>. The string is a colon separated list of group NIDs or
46names, for example "P-521:P-384:P-256".
47
48SSL_set1_groups() and SSL_set1_groups_list() are similar except they set
49supported groups for the SSL structure B<ssl>.
50
51SSL_get1_groups() returns the set of supported groups sent by a client
52in the supported groups extension. It returns the total number of
53supported groups. The B<groups> parameter can be B<NULL> to simply
54return the number of groups for memory allocation purposes. The
55B<groups> array is in the form of a set of group NIDs in preference
56order. It can return zero if the client did not send a supported groups
57extension.
58
59SSL_get_shared_group() returns shared group B<n> for a server-side
60SSL B<ssl>. If B<n> is -1 then the total number of shared groups is
61returned, which may be zero. Other than for diagnostic purposes,
62most applications will only be interested in the first shared group
63so B<n> is normally set to zero. If the value B<n> is out of range,
64NID_undef is returned.
65
66All these functions are implemented as macros.
67
68The curve functions are synonyms for the equivalently named group functions and
69are identical in every respect. They exist because, prior to TLS1.3, there was
70only the concept of supported curves. In TLS1.3 this was renamed to supported
71groups, and extended to include Diffie Hellman groups. The group functions
72should be used in preference.
73
74=head1 NOTES
75
76If an application wishes to make use of several of these functions for
77configuration purposes either on a command line or in a file it should
78consider using the SSL_CONF interface instead of manually parsing options.
79
80=head1 RETURN VALUES
81
82SSL_CTX_set1_groups(), SSL_CTX_set1_groups_list(), SSL_set1_groups() and
83SSL_set1_groups_list(), return 1 for success and 0 for failure.
84
85SSL_get1_groups() returns the number of groups, which may be zero.
86
87SSL_get_shared_group() returns the NID of shared group B<n> or NID_undef if there
88is no shared group B<n>; or the total number of shared groups if B<n>
89is -1.
90
91When called on a client B<ssl>, SSL_get_shared_group() has no meaning and
92returns -1.
93
94=head1 SEE ALSO
95
96L<SSL_CTX_add_extra_chain_cert(3)>
97
98=head1 HISTORY
99
100The curve functions were added in OpenSSL 1.0.2. The equivalent group
101functions were added in OpenSSL 1.1.1.
102
103=head1 COPYRIGHT
104
105Copyright 2013-2018 The OpenSSL Project Authors. All Rights Reserved.
106
107Licensed under the OpenSSL license (the "License").  You may not use
108this file except in compliance with the License.  You can obtain a copy
109in the file LICENSE in the source distribution or at
110L<https://www.openssl.org/source/license.html>.
111
112=cut
113