SSL_CTX_set1_curves
Section: OpenSSL (3)
Updated: 2017-05-25
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NAME
SSL_CTX_set1_curves, SSL_CTX_set1_curves_list, SSL_set1_curves,
SSL_set1_curves_list, SSL_get1_curves, SSL_get_shared_curve,
SSL_CTX_set_ecdh_auto, SSL_set_ecdh_auto - 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);
int SSL_CTX_set_ecdh_auto(SSL_CTX *ctx, int onoff);
int SSL_set_ecdh_auto(SSL *s, int onoff);
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.
SSL_CTX_set_ecdh_auto() and SSL_set_ecdh_auto() set automatic curve
selection for server ctx or ssl to onoff. If onoff is 1 then
the highest preference curve is automatically used for ECDH temporary
keys used during key exchange.
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.
The functions SSL_CTX_set_ecdh_auto() and SSL_set_ecdh_auto() can be used to
make a server always choose the most appropriate curve for a client. If set
it will override any temporary ECDH parameters set by a server. Previous
versions of OpenSSL could effectively only use a single ECDH curve set
using a function such as SSL_CTX_set_ecdh_tmp(). Newer applications should
just call:
SSL_CTX_set_ecdh_auto(ctx, 1);
and they will automatically support ECDH using the most appropriate shared
curve.
RETURN VALUES
SSL_CTX_set1_curves(),
SSL_CTX_set1_curves_list(),
SSL_set1_curves(),
SSL_set1_curves_list(),
SSL_CTX_set_ecdh_auto() and
SSL_set_ecdh_auto()
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.
Index
- NAME
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- SYNOPSIS
-
- DESCRIPTION
-
- NOTES
-
- RETURN VALUES
-
- SEE ALSO
-
- HISTORY
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