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       SSL_CTX_set1_groups, SSL_CTX_set1_groups_list, SSL_set1_groups,
       SSL_set1_groups_list, SSL_get1_groups, SSL_get_shared_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

	#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_get_shared_group(SSL *s, int n);

	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);

       For all of the functions	below that set the supported groups there must
       be at least one group in	the list.

       SSL_CTX_set1_groups() sets the supported	groups for ctx to glistlen
       groups in the array 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.

       SSL_CTX_set1_groups_list() sets the supported groups for	ctx to string
       list. The string	is a colon separated list of group NIDs	or names, for
       example "P-521:P-384:P-256".

       SSL_set1_groups() and SSL_set1_groups_list() are	similar	except they
       set supported groups for	the SSL	structure 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 groups parameter can be NULL to simply return the
       number of groups	for memory allocation purposes.	The 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.

       SSL_get_shared_group() returns shared group n for a server-side SSL
       ssl. If 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 n is
       normally	set to zero. If	the value n is out of range, NID_undef is

       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.

       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

       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_get_shared_group() returns the NID of shared	group n	or NID_undef
       if there	is no shared group n; or the total number of shared groups if
       n is -1.

       When called on a	client ssl, SSL_get_shared_group() has no meaning and
       returns -1.


       The curve functions were	added in OpenSSL 1.0.2.	The equivalent group
       functions were added in OpenSSL 1.1.1.

       Copyright 2013-2018 The OpenSSL Project Authors.	All Rights Reserved.

       Licensed	under the OpenSSL license (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

1.1.1h				  2020-09-22		SSL_CTX_SET1_CURVES(3)


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