OpenSSL/EC POINT add

From Wikibooks, open books for an open world
< OpenSSL
Jump to: navigation, search

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_POINT(s) into the affine co-ordinate 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 generator * n + q * m and stores the result in r. The value n may be NULL in which case the result is just q * m.

EC_POINTs_mul calculates the value generator * n + q[0] * m[0] + ... + q[num-1] * m[num-1]. As 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 for information about the generator.

Return Values[edit]

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_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 return 1 if a precomputation has been done, or 0 if not.