| =pod |
| |
| =head1 NAME |
| |
| SSL_CTX_set1_groups, SSL_CTX_set1_groups_list, SSL_set1_groups, |
| SSL_set1_groups_list, SSL_get1_groups, SSL_get0_iana_groups, |
| SSL_get_shared_group, SSL_get_negotiated_group, SSL_CTX_set1_curves, |
| SSL_CTX_set1_curves_list, SSL_set1_curves, SSL_set1_curves_list, |
| SSL_get1_curves, SSL_get_shared_curve |
| - EC supported curve functions |
| |
| =head1 SYNOPSIS |
| |
| #include <openssl/ssl.h> |
| |
| int SSL_CTX_set1_groups(SSL_CTX *ctx, int *glist, int glistlen); |
| int SSL_CTX_set1_groups_list(SSL_CTX *ctx, char *list); |
| |
| int SSL_set1_groups(SSL *ssl, int *glist, int glistlen); |
| int SSL_set1_groups_list(SSL *ssl, char *list); |
| |
| int SSL_get1_groups(SSL *ssl, int *groups); |
| int SSL_get0_iana_groups(SSL *ssl, uint16_t **out); |
| int SSL_get_shared_group(SSL *s, int n); |
| int SSL_get_negotiated_group(SSL *s); |
| |
| int SSL_CTX_set1_curves(SSL_CTX *ctx, int *clist, int clistlen); |
| int SSL_CTX_set1_curves_list(SSL_CTX *ctx, char *list); |
| |
| int SSL_set1_curves(SSL *ssl, int *clist, int clistlen); |
| int SSL_set1_curves_list(SSL *ssl, char *list); |
| |
| int SSL_get1_curves(SSL *ssl, int *curves); |
| int SSL_get_shared_curve(SSL *s, int n); |
| |
| =head1 DESCRIPTION |
| |
| For all of the functions below that set the supported groups there must be at |
| least one group in the list. A number of these functions identify groups via a |
| unique integer NID value. However, support for some groups may be added by |
| external providers. In this case there will be no NID assigned for the group. |
| When setting such groups applications should use the "list" form of these |
| functions (i.e. SSL_CTX_set1_groups_list() and SSL_set1_groups_list). |
| |
| SSL_CTX_set1_groups() sets the supported groups for B<ctx> to B<glistlen> |
| groups in the array B<glist>. The array consist of all NIDs of groups in |
| preference order. For a TLS client the groups are used directly in the |
| supported groups extension. For a TLS server the groups are used to |
| determine the set of shared groups. Currently supported groups for |
| B<TLSv1.3> are B<NID_X9_62_prime256v1>, B<NID_secp384r1>, B<NID_secp521r1>, |
| B<NID_X25519>, B<NID_X448>, B<NID_ffdhe2048>, B<NID_ffdhe3072>, |
| B<NID_ffdhe4096>, B<NID_ffdhe6144> and B<NID_ffdhe8192>. |
| |
| SSL_CTX_set1_groups_list() sets the supported groups for B<ctx> to |
| string B<list>. The string is a colon separated list of group NIDs or |
| names, for example "P-521:P-384:P-256:X25519:ffdhe2048". Currently supported |
| groups for B<TLSv1.3> are B<P-256>, B<P-384>, B<P-521>, B<X25519>, B<X448>, |
| B<ffdhe2048>, B<ffdhe3072>, B<ffdhe4096>, B<ffdhe6144>, B<ffdhe8192>. Support |
| for other groups may be added by external providers. |
| |
| SSL_set1_groups() and SSL_set1_groups_list() are similar except they set |
| supported groups for the SSL structure B<ssl>. |
| |
| SSL_get1_groups() returns the set of supported groups sent by a client |
| in the supported groups extension. It returns the total number of |
| supported groups. The B<groups> parameter can be B<NULL> to simply |
| return the number of groups for memory allocation purposes. The |
| B<groups> array is in the form of a set of group NIDs in preference |
| order. It can return zero if the client did not send a supported groups |
| extension. If a supported group NID is unknown then the value is set to the |
| bitwise OR of TLSEXT_nid_unknown (0x1000000) and the id of the group. |
| |
| SSL_get0_iana_groups() retrieves the list of groups sent by the |
| client in the supported_groups extension. The B<*out> array of bytes |
| is populated with the host-byte-order representation of the uint16_t group |
| identifiers, as assigned by IANA. The group list is returned in the same order |
| that was received in the ClientHello. The return value is the number of groups, |
| not the number of bytes written. |
| |
| SSL_get_shared_group() returns the NID of the shared group B<n> for a |
| server-side SSL B<ssl>. If B<n> is -1 then the total number of shared groups is |
| returned, which may be zero. Other than for diagnostic purposes, |
| most applications will only be interested in the first shared group |
| so B<n> is normally set to zero. If the value B<n> is out of range, |
| NID_undef is returned. If the NID for the shared group is unknown then the value |
| is set to the bitwise OR of TLSEXT_nid_unknown (0x1000000) and the id of the |
| group. |
| |
| SSL_get_negotiated_group() returns the NID of the negotiated group used for |
| the handshake key exchange process. For TLSv1.3 connections this typically |
| reflects the state of the current connection, though in the case of PSK-only |
| resumption, the returned value will be from a previous connection. For earlier |
| TLS versions, when a session has been resumed, it always reflects the group |
| used for key exchange during the initial handshake (otherwise it is from the |
| current, non-resumption, connection). This can be called by either client or |
| server. If the NID for the shared group is unknown then the value is set to the |
| bitwise OR of TLSEXT_nid_unknown (0x1000000) and the id of the group. |
| |
| All these functions are implemented as macros. |
| |
| The curve functions are synonyms for the equivalently named group functions and |
| are identical in every respect. They exist because, prior to TLS1.3, there was |
| only the concept of supported curves. In TLS1.3 this was renamed to supported |
| groups, and extended to include Diffie Hellman groups. The group functions |
| should be used in preference. |
| |
| =head1 NOTES |
| |
| If an application wishes to make use of several of these functions for |
| configuration purposes either on a command line or in a file it should |
| consider using the SSL_CONF interface instead of manually parsing options. |
| |
| =head1 RETURN VALUES |
| |
| SSL_CTX_set1_groups(), SSL_CTX_set1_groups_list(), SSL_set1_groups() and |
| SSL_set1_groups_list(), return 1 for success and 0 for failure. |
| |
| SSL_get1_groups() returns the number of groups, which may be zero. |
| |
| SSL_get0_iana_groups() returns the number of (uint16_t) groups, which may be zero. |
| |
| SSL_get_shared_group() returns the NID of shared group B<n> or NID_undef if there |
| is no shared group B<n>; or the total number of shared groups if B<n> |
| is -1. |
| |
| When called on a client B<ssl>, SSL_get_shared_group() has no meaning and |
| returns -1. |
| |
| SSL_get_negotiated_group() returns the NID of the negotiated group used for |
| key exchange, or NID_undef if there was no negotiated group. |
| |
| =head1 SEE ALSO |
| |
| L<ssl(7)>, |
| L<SSL_CTX_add_extra_chain_cert(3)> |
| |
| =head1 HISTORY |
| |
| The curve functions were added in OpenSSL 1.0.2. The equivalent group |
| functions were added in OpenSSL 1.1.1. The SSL_get_negotiated_group() function |
| was added in OpenSSL 3.0.0. |
| |
| =head1 COPYRIGHT |
| |
| Copyright 2013-2022 The OpenSSL Project Authors. All Rights Reserved. |
| |
| Licensed under the Apache License 2.0 (the "License"). You may not use |
| this file except in compliance with the License. You can obtain a copy |
| in the file LICENSE in the source distribution or at |
| L<https://www.openssl.org/source/license.html>. |
| |
| =cut |