goto err;
}
- /*-
- * check the discriminant:
- * y^2 = x^3 + a*x + b is an elliptic curve <=> 4*a^3 + 27*b^2 != 0 (mod p)
- * 0 =< a, b < p
- */
+ /*-
+ * check the discriminant:
+ * y^2 = x^3 + a*x + b is an elliptic curve <=> 4*a^3 + 27*b^2 != 0 (mod p)
+ * 0 =< a, b < p
+ */
if (BN_is_zero(a)) {
if (BN_is_zero(b))
goto err;
if (Z6 == NULL)
goto err;
- /*-
- * We have a curve defined by a Weierstrass equation
- * y^2 = x^3 + a*x + b.
- * The point to consider is given in Jacobian projective coordinates
- * where (X, Y, Z) represents (x, y) = (X/Z^2, Y/Z^3).
- * Substituting this and multiplying by Z^6 transforms the above equation into
- * Y^2 = X^3 + a*X*Z^4 + b*Z^6.
- * To test this, we add up the right-hand side in 'rh'.
- */
+ /*-
+ * We have a curve defined by a Weierstrass equation
+ * y^2 = x^3 + a*x + b.
+ * The point to consider is given in Jacobian projective coordinates
+ * where (X, Y, Z) represents (x, y) = (X/Z^2, Y/Z^3).
+ * Substituting this and multiplying by Z^6 transforms the above equation into
+ * Y^2 = X^3 + a*X*Z^4 + b*Z^6.
+ * To test this, we add up the right-hand side in 'rh'.
+ */
/* rh := X^2 */
if (!field_sqr(group, rh, point->X, ctx))
if (Zb23 == NULL)
goto end;
- /*-
- * We have to decide whether
- * (X_a/Z_a^2, Y_a/Z_a^3) = (X_b/Z_b^2, Y_b/Z_b^3),
- * or equivalently, whether
- * (X_a*Z_b^2, Y_a*Z_b^3) = (X_b*Z_a^2, Y_b*Z_a^3).
- */
+ /*-
+ * We have to decide whether
+ * (X_a/Z_a^2, Y_a/Z_a^3) = (X_b/Z_b^2, Y_b/Z_b^3),
+ * or equivalently, whether
+ * (X_a*Z_b^2, Y_a*Z_b^3) = (X_b*Z_a^2, Y_b*Z_a^3).
+ */
if (!b->Z_is_one) {
if (!field_sqr(group, Zb23, b->Z, ctx))