Commit 86a921af authored by Bodo Möller's avatar Bodo Möller
Browse files

handle negative scalars correctly when doing point multiplication

parent 616df356

crypto/ec/ec_mult.c

+8 −0
Original line number Diff line number Diff line
@@ -187,10 +187,18 @@ int EC_POINTs_mul(const EC_GROUP *group, EC_POINT *r, BIGNUM *scalar, 
		if (i < num)

			{

			if (!EC_POINT_copy(val_sub[i][0], points[i])) goto err;

			if (scalars[i]->neg)

				{

				if (!EC_POINT_invert(group, val_sub[i][0], ctx)) goto err;

				}

			}

		else

			{

			if (!EC_POINT_copy(val_sub[i][0], generator)) goto err;

			if (scalar->neg)

				{

				if (!EC_POINT_invert(group, val_sub[i][0], ctx)) goto err;

				}

			}



		if (wsize[i] > 1)

crypto/ec/ectest.c

+17 −2
Original line number Diff line number Diff line
@@ -528,6 +528,21 @@ int main(int argc, char *argv[]) 
		if (0 != EC_POINT_cmp(group, P, R, ctx)) ABORT;

		if (0 != EC_POINT_cmp(group, R, Q, ctx)) ABORT;



		fprintf(stdout, ".");

		fflush(stdout);



		if (!BN_pseudo_rand(y, BN_num_bits(y), 0, 0)) ABORT;

		if (!BN_copy(z, y)) ABORT;

		z->neg = 1;



		points[0] = Q;

		points[1] = Q;

		scalars[0] = y;

		scalars[1] = z;



		if (!EC_POINTs_mul(group, P, NULL, 2, points, scalars, ctx)) ABORT;

		if (!EC_POINT_is_at_infinity(group, P)) ABORT;



		fprintf(stdout, " ok\n\n");

	}