add test of power

include/mcl/ec.hpp

@@ -368,6 +368,7 @@ public:
 	}
 	static inline void mulArray(EcT& z, const EcT& x, const fp::Unit *y, size_t yn, bool isNegative)
 	{
+		x.normalize();
 		EcT tmp;
 		const EcT *px = &x;
 		if (&z == &x) {

include/mcl/util.hpp

@@ -139,12 +139,12 @@ void getRandVal(T *out, RG& rg, const T *in, size_t bitSize)
 	@param x [in]
 	@param y [in]
 	@param n [in] size of y[]
+	@note &out != x and out = the unit element of G
 */
 template<class G, class T>
 void powerGeneric(G& out, const G& x, const T *y, size_t n, void mul(G&, const G&, const G&) , void square(G&, const G&)){
 #if 1
 	assert(&out != &x);
-	G t(x);
 	while (n > 0) {
 		if (y[n - 1]) break;
 		n--;
@@ -165,7 +165,7 @@ void powerGeneric(G& out, const G& x, const T *y, size_t n, void mul(G&, const G
 		for (int j = m - 1; j >= 0; j--) {
 			square(out, out);
 			if (v & (T(1) << j)) {
-				mul(out, out, t);
+				mul(out, out, x);
 			}
 		}
 	}

test/ec_test.cpp

@@ -31,6 +31,29 @@ struct Test {
 		Ec::neg(P, O);
 		CYBOZU_TEST_EQUAL(P, O);
 	}
+	void pow2(Ec& Q, const Ec& P, int n) const
+	{
+		Q = P;
+		for (int i = 0; i < n; i++) {
+			Q += Q;
+		}
+	}
+	void pow2test(const Ec& P, int n) const
+	{
+		Ec Q, R;
+		pow2(Q, P, n);
+		Q -= P; // Q = (2^n - 1)P
+		Fp x = 1;
+		for (int i = 0; i < n; i++) {
+			x += x;
+		}
+		x -= 1; // x = 2^n - 1
+		Ec::mul(R, P, x);
+		CYBOZU_TEST_EQUAL(Q, R);
+		Q = P;
+		Ec::mul(Q, Q, x);
+		CYBOZU_TEST_EQUAL(Q, R);
+	}
 	void ope() const
 	{
 		Fp x(para.gx);
@@ -96,6 +119,22 @@ struct Test {
 		CYBOZU_TEST_EQUAL(R, -P);
 		R += P; // Ec::mul(R, P, n);
 		CYBOZU_TEST_ASSERT(R.isZero());
+		{
+			const int tbl[] = { 1, 2, 63, 64, 65, 127, 128, 129 };
+			for (size_t i = 0; i < CYBOZU_NUM_OF_ARRAY(tbl); i++) {
+				pow2test(P, tbl[i]);
+			}
+		}
+		{
+			Ec::mul(Q, P, 0);
+			CYBOZU_TEST_ASSERT(Q.isZero());
+			Q = P;
+			CYBOZU_TEST_ASSERT(!Q.isZero());
+			Ec::mul(Q, Q, 0);
+			CYBOZU_TEST_ASSERT(Q.isZero());
+			Ec::mul(Q, P, 1);
+			CYBOZU_TEST_EQUAL(P, Q);
+		}
 	}
 
 	void mul() const