Method: OpenSSL::PKey::EC::Point#mul

Defined in:

ossl_pkey_ec.c

#mul(bn1[, bn2]) ⇒ Object #mul(bns, points[, bn2]) ⇒ Object

Performs elliptic curve point multiplication.

The first form calculates bn1 * point + bn2 * G, where G is the generator of the group of point. bn2 may be omitted, and in that case, the result is just bn1 * point.

The second form calculates bns[0] * point + bns[1] * points[0] + ... + bns[-1] * points[-1] + bn2 * G. bn2 may be omitted. bns must be an array of OpenSSL::BN. points must be an array of OpenSSL::PKey::EC::Point. Please note that points[0] is not multiplied by bns[0], but bns[1].

# File 'ossl_pkey_ec.c', line 1495

static VALUE ossl_ec_point_mul(int argc, VALUE *argv, VALUE self)
{
    EC_POINT *point_self, *point_result;
    const EC_GROUP *group;
    VALUE group_v = rb_attr_get(self, id_i_group);
    VALUE arg1, arg2, arg3, result;
    const BIGNUM *bn_g = NULL;

    GetECPoint(self, point_self);
    GetECGroup(group_v, group);

    result = rb_obj_alloc(cEC_POINT);
    ossl_ec_point_initialize(1, &group_v, result);
    GetECPoint(result, point_result);

    rb_scan_args(argc, argv, "12", &arg1, &arg2, &arg3);
    if (!RB_TYPE_P(arg1, T_ARRAY)) {
	BIGNUM *bn = GetBNPtr(arg1);

	if (!NIL_P(arg2))
	    bn_g = GetBNPtr(arg2);
	if (EC_POINT_mul(group, point_result, bn_g, point_self, bn, ossl_bn_ctx) != 1)
	    ossl_raise(eEC_POINT, NULL);
    } else {
#if (defined(OPENSSL_VERSION_MAJOR) && OPENSSL_VERSION_MAJOR >= 3) || defined(LIBRESSL_VERSION_NUMBER)
        rb_raise(rb_eNotImpError, "calling #mul with arrays is not" \
                 "supported by this OpenSSL version");
#else
	/*
	 * bignums | arg1[0] | arg1[1] | arg1[2] | ...
	 * points  | self    | arg2[0] | arg2[1] | ...
	 */
	long i, num;
	VALUE bns_tmp, tmp_p, tmp_b;
	const EC_POINT **points;
	const BIGNUM **bignums;

	Check_Type(arg1, T_ARRAY);
	Check_Type(arg2, T_ARRAY);
	if (RARRAY_LEN(arg1) != RARRAY_LEN(arg2) + 1) /* arg2 must be 1 larger */
	    ossl_raise(rb_eArgError, "bns must be 1 longer than points; see the documentation");

        rb_warning("OpenSSL::PKey::EC::Point#mul(ary, ary) is deprecated; " \
                   "use #mul(bn) form instead");

	num = RARRAY_LEN(arg1);
	bns_tmp = rb_ary_tmp_new(num);
	bignums = ALLOCV_N(const BIGNUM *, tmp_b, num);
	for (i = 0; i < num; i++) {
	    VALUE item = RARRAY_AREF(arg1, i);
	    bignums[i] = GetBNPtr(item);
	    rb_ary_push(bns_tmp, item);
	}

	points = ALLOCV_N(const EC_POINT *, tmp_p, num);
	points[0] = point_self; /* self */
	for (i = 0; i < num - 1; i++)
	    GetECPoint(RARRAY_AREF(arg2, i), points[i + 1]);

	if (!NIL_P(arg3))
	    bn_g = GetBNPtr(arg3);

	if (EC_POINTs_mul(group, point_result, bn_g, num, points, bignums, ossl_bn_ctx) != 1) {
	    ALLOCV_END(tmp_b);
	    ALLOCV_END(tmp_p);
	    ossl_raise(eEC_POINT, NULL);
	}

	ALLOCV_END(tmp_b);
	ALLOCV_END(tmp_p);
#endif
    }

    return result;
}