NAME
EC_POINT_add,
EC_POINT_dbl,
EC_POINT_invert,
EC_POINT_is_at_infinity,
EC_POINT_is_on_curve,
EC_POINT_cmp,
EC_POINT_make_affine,
EC_POINTs_make_affine,
EC_POINTs_mul, EC_POINT_mul,
EC_GROUP_precompute_mult,
EC_GROUP_have_precompute_mult —
perform mathematical operations and
tests on EC_POINT objects
SYNOPSIS
#include
<openssl/ec.h>
#include <openssl/bn.h>
int
EC_POINT_add(const EC_GROUP
*group, EC_POINT *r, const
EC_POINT *a, const EC_POINT *b,
BN_CTX *ctx);
int
EC_POINT_dbl(const EC_GROUP
*group, EC_POINT *r, const
EC_POINT *a, BN_CTX *ctx);
int
EC_POINT_invert(const EC_GROUP
*group, EC_POINT *a, BN_CTX
*ctx);
int
EC_POINT_is_at_infinity(const EC_GROUP
*group, const EC_POINT *p);
int
EC_POINT_is_on_curve(const EC_GROUP
*group, const EC_POINT *point,
BN_CTX *ctx);
int
EC_POINT_cmp(const EC_GROUP
*group, const EC_POINT *a, const
EC_POINT *b, BN_CTX *ctx);
int
EC_POINT_make_affine(const EC_GROUP
*group, EC_POINT *point, BN_CTX
*ctx);
int
EC_POINTs_make_affine(const EC_GROUP
*group, size_t num, EC_POINT
*points[], BN_CTX *ctx);
int
EC_POINTs_mul(const EC_GROUP
*group, EC_POINT *r, const
BIGNUM *n, size_t num, const
EC_POINT *p[], const BIGNUM *m[],
BN_CTX *ctx);
int
EC_POINT_mul(const EC_GROUP
*group, EC_POINT *r, const
BIGNUM *n, const EC_POINT *q,
const BIGNUM *m, BN_CTX
*ctx);
int
EC_GROUP_precompute_mult(EC_GROUP
*group, BN_CTX *ctx);
int
EC_GROUP_have_precompute_mult(const
EC_GROUP *group);
DESCRIPTION
These functions operate on EC_POINT objects created by EC_POINT_new(3).
EC_POINT_add()
adds the two points a and b and
places the result in r. Similarly
EC_POINT_dbl()
doubles the point a and places the result in
r. In both cases it is valid for
r to be one of a or
b.
EC_POINT_invert()
calculates the inverse of the supplied point a. The
result is placed back in a.
The function
EC_POINT_is_at_infinity()
tests whether the supplied point is at infinity or not.
EC_POINT_is_on_curve()
tests whether the supplied point is on the curve or not.
EC_POINT_cmp()
compares the two supplied points and tests whether or not they are
equal.
The functions
EC_POINT_make_affine()
and
EC_POINTs_make_affine()
force the internal representation of the EC_POINTs
into the affine coordinate system. In the case of
EC_POINTs_make_affine(), the value
num provides the number of points in the array
points to be forced.
EC_POINT_mul()
calculates the value
and stores the result in r. The value
n may be NULL, in which case
the result is just
q * m.EC_POINTs_mul()
only supports the values 0 and 1 for num. If it is 1,
then EC_POINTs_mul() calculates the value
generator * n + q[0] *
m[0].If num is 0 then q and
m must be NULL, and the result
is just
generator * nAs for
EC_POINT_mul(),
the value n may be NULL.
The function
EC_GROUP_precompute_mult()
stores multiples of the generator for faster point multiplication, whilst
EC_GROUP_have_precompute_mult()
tests whether precomputation has already been done. See
EC_GROUP_copy(3) for information about the generator.
RETURN VALUES
The following functions return 1 on success or 0 on error:
EC_POINT_add(),
EC_POINT_dbl(),
EC_POINT_invert(),
EC_POINT_make_affine(),
EC_POINTs_make_affine(),
EC_POINT_mul(),
EC_POINTs_mul(), and
EC_GROUP_precompute_mult().
EC_POINT_is_at_infinity() returns 1 if the
point is at infinity or 0 otherwise.
EC_POINT_is_on_curve() returns 1 if the
point is on the curve, 0 if not, or -1 on error.
EC_POINT_cmp() returns 1 if the points are
not equal, 0 if they are, or -1 on error.
EC_GROUP_have_precompute_mult() returns 1
if a precomputation has been done or 0 if not.
SEE ALSO
d2i_ECPKParameters(3), EC_GFp_simple_method(3), EC_GROUP_copy(3), EC_GROUP_new(3), EC_KEY_new(3), EC_POINT_new(3)
HISTORY
EC_POINT_add(),
EC_POINT_dbl(),
EC_POINT_invert(),
EC_POINT_is_at_infinity(),
EC_POINT_is_on_curve(),
EC_POINT_cmp(),
EC_POINT_make_affine(),
EC_POINTs_make_affine(),
EC_POINTs_mul(),
EC_POINT_mul(), and
EC_GROUP_precompute_mult() first appeared in OpenSSL
0.9.7 and have been available since OpenBSD 3.2.
EC_GROUP_have_precompute_mult() first
appeared in OpenSSL 0.9.8 and has been available since
OpenBSD 4.5.