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SSL_CTX_set1_curves(3) OpenSSL SSL_CTX_set1_curves(3)
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
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);
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
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
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.
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
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:
and they will automatically support ECDH using the most appropriate
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
These functions were first added to OpenSSL 1.0.2.
1.0.2h 2016-05-03 SSL_CTX_set1_curves(3)