## table of contents

SSL_CTX_SET1_CURVES(3SSL) | OpenSSL | SSL_CTX_SET1_CURVES(3SSL) |

# NAME¶

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# SYNOPSIS¶

#include <openssl/ssl.h> 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);

# DESCRIPTION¶

*SSL_CTX_set1_curves()*sets the supported curves for

**ctx**to

**clistlen**curves in the array

**clist**. The array consist of all NIDs of curves in preference order. For a TLS client the curves are used directly in the supported curves extension. For a TLS server the curves are used to determine the set of shared curves.

*SSL_CTX_set1_curves_list()* sets the supported curves for
**ctx** to string **list**. The string is a colon separated list of
curve NIDs or names, for example "P-521:P-384:P-256".

*SSL_set1_curves()* and *SSL_set1_curves_list()* are
similar except they set supported curves for the SSL structure
**ssl**.

*SSL_get1_curves()* returns the set of supported curves sent
by a client in the supported curves extension. It returns the total number
of supported curves. The **curves** parameter can be **NULL** to
simply return the number of curves for memory allocation purposes. The
**curves** array is in the form of a set of curve NIDs in preference
order. It can return zero if the client did not send a supported curves
extension.

*SSL_get_shared_curve()* returns shared curve **n** for a
server-side SSL **ssl**. If **n** is -1 then the total number of
shared curves is returned, which may be zero. Other than for diagnostic
purposes, most applications will only be interested in the first shared
curve so **n** is normally set to zero. If the value **n** is out of
range, NID_undef is returned.

All these functions are implemented as macros.

# 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.# RETURN VALUES¶

*SSL_CTX_set1_curves()*,

*SSL_CTX_set1_curves_list()*,

*SSL_set1_curves()*and

*SSL_set1_curves_list()*, return 1 for success and 0 for failure.

*SSL_get1_curves()* returns the number of curves, which may
be zero.

*SSL_get_shared_curve()* returns the NID of shared curve
**n** or NID_undef if there is no shared curve **n**; or the total
number of shared curves if **n** is -1.

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

# SEE ALSO¶

SSL_CTX_add_extra_chain_cert(3)# HISTORY¶

These functions were first added to OpenSSL 1.0.2.# COPYRIGHT¶

Copyright 2013-2016 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 <https://www.openssl.org/source/license.html>.

2018-11-28 | 1.1.0j |