EC_POINT_new(3) OpenSSL EC_POINT_new(3) NNAAMMEE EC_POINT_new, EC_POINT_free, EC_POINT_clear_free, EC_POINT_copy, EC_POINT_dup, EC_POINT_method_of, EC_POINT_set_to_infinity, EC_POINT_set_Jprojective_coordinates, EC_POINT_get_Jprojective_coordi- nates_GFp, EC_POINT_set_affine_coordinates_GFp, EC_POINT_get_affine_coordinates_GFp, EC_POINT_set_compressed_coordi- nates_GFp, EC_POINT_set_affine_coordinates_GF2m, EC_POINT_get_affine_coordinates_GF2m, EC_POINT_set_compressed_coordi- nates_GF2m, EC_POINT_point2oct, EC_POINT_oct2point, EC_POINT_point2bn, EC_POINT_bn2point, EC_POINT_point2hex, EC_POINT_hex2point - Functions for creating, destroying and manipulating EECC__PPOOIINNTT objects. SSYYNNOOPPSSIISS #include #include EC_POINT *EC_POINT_new(const EC_GROUP *group); void EC_POINT_free(EC_POINT *point); void EC_POINT_clear_free(EC_POINT *point); int EC_POINT_copy(EC_POINT *dst, const EC_POINT *src); EC_POINT *EC_POINT_dup(const EC_POINT *src, const EC_GROUP *group); const EC_METHOD *EC_POINT_method_of(const EC_POINT *point); int EC_POINT_set_to_infinity(const EC_GROUP *group, EC_POINT *point); int EC_POINT_set_Jprojective_coordinates_GFp(const EC_GROUP *group, EC_POINT *p, const BIGNUM *x, const BIGNUM *y, const BIGNUM *z, BN_CTX *ctx); int EC_POINT_get_Jprojective_coordinates_GFp(const EC_GROUP *group, const EC_POINT *p, BIGNUM *x, BIGNUM *y, BIGNUM *z, BN_CTX *ctx); int EC_POINT_set_affine_coordinates_GFp(const EC_GROUP *group, EC_POINT *p, const BIGNUM *x, const BIGNUM *y, BN_CTX *ctx); int EC_POINT_get_affine_coordinates_GFp(const EC_GROUP *group, const EC_POINT *p, BIGNUM *x, BIGNUM *y, BN_CTX *ctx); int EC_POINT_set_compressed_coordinates_GFp(const EC_GROUP *group, EC_POINT *p, const BIGNUM *x, int y_bit, BN_CTX *ctx); int EC_POINT_set_affine_coordinates_GF2m(const EC_GROUP *group, EC_POINT *p, const BIGNUM *x, const BIGNUM *y, BN_CTX *ctx); int EC_POINT_get_affine_coordinates_GF2m(const EC_GROUP *group, const EC_POINT *p, BIGNUM *x, BIGNUM *y, BN_CTX *ctx); int EC_POINT_set_compressed_coordinates_GF2m(const EC_GROUP *group, EC_POINT *p, const BIGNUM *x, int y_bit, BN_CTX *ctx); size_t EC_POINT_point2oct(const EC_GROUP *group, const EC_POINT *p, point_conversion_form_t form, unsigned char *buf, size_t len, BN_CTX *ctx); int EC_POINT_oct2point(const EC_GROUP *group, EC_POINT *p, const unsigned char *buf, size_t len, BN_CTX *ctx); BIGNUM *EC_POINT_point2bn(const EC_GROUP *, const EC_POINT *, point_conversion_form_t form, BIGNUM *, BN_CTX *); EC_POINT *EC_POINT_bn2point(const EC_GROUP *, const BIGNUM *, EC_POINT *, BN_CTX *); char *EC_POINT_point2hex(const EC_GROUP *, const EC_POINT *, point_conversion_form_t form, BN_CTX *); EC_POINT *EC_POINT_hex2point(const EC_GROUP *, const char *, EC_POINT *, BN_CTX *); DDEESSCCRRIIPPTTIIOONN An EC_POINT represents a point on a curve. A new point is constructed by calling the function EC_POINT_new and providing the ggrroouupp object that the point relates to. EC_POINT_free frees the memory associated with the EC_POINT. EC_POINT_clear_free destroys any sensitive data held within the EC_POINT and then frees its memory. EC_POINT_copy copies the point ssrrcc into ddsstt. Both ssrrcc and ddsstt must use the same EC_METHOD. EC_POINT_dup creates a new EC_POINT object and copies the content from ssrrcc to the newly created EC_POINT object. EC_POINT_method_of obtains the EC_METHOD associated with ppooiinntt. A valid point on a curve is the special point at infinity. A point is set to be at infinity by calling EC_POINT_set_to_infinity. The affine co-ordinates for a point describe a point in terms of its x and y position. The functions EC_POINT_set_affine_coordinates_GFp and EC_POINT_set_affine_coordinates_GF2m set the xx and yy co-ordinates for the point pp defined over the curve given in ggrroouupp. As well as the affine co-ordinates, a point can alternatively be described in terms of its Jacobian projective co-ordinates (for Fp curves only). Jacobian projective co-ordinates are expressed as three values x, y and z. Working in this co-ordinate system provides more efficient point multiplication operations. A mapping exists between Jacobian projective co-ordinates and affine co-ordinates. A Jacobian projective co-ordinate (x, y, z) can be written as an affine co-ordi- nate as (x/(z^2), y/(z^3)). Conversion to Jacobian projective to affine co-ordinates is simple. The co-ordinate (x, y) is mapped to (x, y, 1). To set or get the projective co-ordinates use EC_POINT_set_Jprojec- tive_coordinates_GFp and EC_POINT_get_Jprojective_coordinates_GFp respectively. Points can also be described in terms of their compressed co-ordinates. For a point (x, y), for any given value for x such that the point is on the curve there will only ever be two possible values for y. Therefore a point can be set using the EC_POINT_set_compressed_coordinates_GFp and EC_POINT_set_compressed_coordinates_GF2m functions where xx is the x co-ordinate and yy__bbiitt is a value 0 or 1 to identify which of the two possible values for y should be used. In addition EC_POINTs can be converted to and from various external representations. Supported representations are octet strings, BIGNUMs and hexadecimal. Octet strings are stored in a buffer along with an associated buffer length. A point held in a BIGNUM is calculated by converting the point to an octet string and then converting that octet string into a BIGNUM integer. Points in hexadecimal format are stored in a NULL terminated character string where each character is one of the printable values 0-9 or A-F (or a-f). The functions EC_POINT_point2oct, EC_POINT_oct2point, EC_POINT_point2bn, EC_POINT_bn2point, EC_POINT_point2hex and EC_POINT_hex2point convert from and to EC_POINTs for the formats: octet string, BIGNUM and hexadecimal respectively. The function EC_POINT_point2oct must be supplied with a buffer long enough to store the octet string. The return value provides the number of octets stored. Calling the function with a NULL buffer will not per- form the conversion but will still return the required buffer length. The function EC_POINT_point2hex will allocate sufficient memory to store the hexadecimal string. It is the caller's responsibility to free this memory with a subsequent call to _O_P_E_N_S_S_L___f_r_e_e_(_). RREETTUURRNN VVAALLUUEESS EC_POINT_new and EC_POINT_dup return the newly allocated EC_POINT or NULL on error. The following functions return 1 on success or 0 on error: EC_POINT_copy, EC_POINT_set_to_infinity, EC_POINT_set_Jprojective_coor- dinates_GFp, EC_POINT_get_Jprojective_coordinates_GFp, EC_POINT_set_affine_coordinates_GFp, EC_POINT_get_affine_coordi- nates_GFp, EC_POINT_set_compressed_coordinates_GFp, EC_POINT_set_affine_coordinates_GF2m, EC_POINT_get_affine_coordi- nates_GF2m, EC_POINT_set_compressed_coordinates_GF2m and EC_POINT_oct2point. EC_POINT_method_of returns the EC_METHOD associated with the supplied EC_POINT. EC_POINT_point2oct returns the length of the required buffer, or 0 on error. EC_POINT_point2bn returns the pointer to the BIGNUM supplied, or NULL on error. EC_POINT_bn2point returns the pointer to the EC_POINT supplied, or NULL on error. EC_POINT_point2hex returns a pointer to the hex string, or NULL on error. EC_POINT_hex2point returns the pointer to the EC_POINT supplied, or NULL on error. SSEEEE AALLSSOO _c_r_y_p_t_o(3), _e_c(3), _E_C___G_R_O_U_P___n_e_w(3), _E_C___G_R_O_U_P___c_o_p_y(3), _E_C___P_O_I_N_T___a_d_d(3), _E_C___K_E_Y___n_e_w(3), _E_C___G_F_p___s_i_m_p_l_e___m_e_t_h_o_d(3), _d_2_i___E_C_P_K_P_a_r_a_m_e_t_e_r_s(3) 1.0.2u 2019-12-20 EC_POINT_new(3)