add bls12::mapToG2

include/mcl/bls12.hpp

@@ -14,16 +14,75 @@ namespace mcl { namespace bls12 {
 using mcl::CurveParam;
 using mcl::getCurveParam;
 
+template<class Fp>
+struct MapToT {
+	typedef mcl::Fp2T<Fp> Fp2;
+	typedef mcl::EcT<Fp> G1;
+	typedef mcl::EcT<Fp2> G2;
+	typedef util::HaveFrobenius<G2> G2withF;
+	mpz_class z_;
+	/*
+		Q = (z(z-1)-1)P + Frob((z-1)P) + Frob^2(2P)
+	*/
+	void mulByCofactor(G2& Q, const G2& P) const
+	{
+		G2 T0, T1;
+		G2::mulGeneric(T0, P, z_ - 1);
+		G2::mulGeneric(T1, T0, z_);
+		T1 -= P;
+		G2withF::Frobenius(T0, T0);
+		T0 += T1;
+		G2::dbl(T1, P);
+		G2withF::Frobenius2(T1, T1);
+		G2::add(Q, T0, T1);
+	}
+	void init(const mpz_class& z)
+	{
+		z_ = z;
+	}
+	template<class G, class F>
+	void calc(G& P, const F& t) const
+	{
+		F x = t;
+		for (;;) {
+			F y;
+			G::getWeierstrass(y, x);
+			if (F::squareRoot(y, y)) {
+				P.set(x, y, false);
+				return;
+			}
+			*x.getFp0() += Fp::one();
+		}
+	}
+	void calcG1(G1& P, const Fp& t) const
+	{
+		calc<G1, Fp>(P, t);
+		assert(P.isValid());
+	}
+	/*
+		get the element in G2 by multiplying the cofactor
+	*/
+	void calcG2(G2& P, const Fp2& t) const
+	{
+		calc<G2, Fp2>(P, t);
+		assert(cofactor_ != 0);
+		mulByCofactor(P, P);
+		assert(!P.isZero());
+	}
+};
+
 template<class Fp>
 struct ParamT : public util::CommonParamT<Fp> {
 	typedef util::CommonParamT<Fp> Common;
 	typedef Fp2T<Fp> Fp2;
 	typedef mcl::EcT<Fp> G1;
 	typedef mcl::EcT<Fp2> G2;
+	MapToT<Fp> mapTo;
 
 	void init(const CurveParam& cp = CurveFp381, fp::Mode mode = fp::FP_AUTO)
 	{
 		Common::initCommonParam(cp, mode, true);
+		mapTo.init(this->z);
 	}
 };
 
@@ -107,6 +166,29 @@ struct BLS12T {
 #endif
 	}
 ////////////////////////////////////////////////////////////////////////////////////
+	static void mapToG1(G1& P, const Fp& x) { param.mapTo.calcG1(P, x); }
+	static void mapToG2(G2& P, const Fp2& x) { param.mapTo.calcG2(P, x); }
+	static void hashAndMapToG1(G1& P, const void *buf, size_t bufSize)
+	{
+		Fp t;
+		t.setHashOf(buf, bufSize);
+		mapToG1(P, t);
+	}
+	static void hashAndMapToG2(G2& P, const void *buf, size_t bufSize)
+	{
+		Fp2 t;
+		t.a.setHashOf(buf, bufSize);
+		t.b.clear();
+		mapToG2(P, t);
+	}
+	static void hashAndMapToG1(G1& P, const std::string& str)
+	{
+		hashAndMapToG1(P, str.c_str(), str.size());
+	}
+	static void hashAndMapToG2(G2& P, const std::string& str)
+	{
+		hashAndMapToG2(P, str.c_str(), str.size());
+	}
 };
 
 template<class Fp>

test/bls12_test.cpp

@@ -149,7 +149,6 @@ void testSetStr(const G2& Q0)
 	}
 }
 
-#if 0
 void testMapToG1()
 {
 	G1 g;
@@ -160,13 +159,6 @@ void testMapToG1()
 		G1::mul(gr, g, BLS12::param.r);
 		CYBOZU_TEST_ASSERT(gr.isZero());
 	}
-#ifndef MCL_AVOID_EXCEPTION_TEST
-	if (BLS12::param.b == 2) {
-		CYBOZU_TEST_EXCEPTION(BLS12::mapToG1(g, 0), cybozu::Exception);
-		CYBOZU_TEST_EXCEPTION(BLS12::mapToG1(g, BLS12::param.mapTo.c1), cybozu::Exception);
-		CYBOZU_TEST_EXCEPTION(BLS12::mapToG1(g, -BLS12::param.mapTo.c1), cybozu::Exception);
-	}
-#endif
 }
 
 void testMapToG2()
@@ -179,17 +171,11 @@ void testMapToG2()
 		G2::mul(gr, g, BLS12::param.r);
 		CYBOZU_TEST_ASSERT(gr.isZero());
 	}
-#ifndef MCL_AVOID_EXCEPTION_TEST
-	if (BLS12::param.b == 2) {
-		CYBOZU_TEST_EXCEPTION(BLS12::mapToG2(g, 0), cybozu::Exception);
-	}
-#endif
 	Fp x;
 	x.setHashOf("abc");
 	BLS12::mapToG2(g, Fp2(x, 0));
 	CYBOZU_TEST_ASSERT(g.isValid());
 }
-#endif
 
 void testPrecomputed(const G1& P, const G2& Q)
 {
@@ -354,7 +340,7 @@ CYBOZU_TEST_AUTO(naive)
 		testTrivial(P, Q);
 		testSetStr(Q);
 //		testMapToG1();
-//		testMapToG2();
+		testMapToG2();
 		testPairing(P, Q, ts.e);
 		testPrecomputed(P, Q);
 		testMillerLoop2(P, Q);

test/bn_test.cpp

@@ -339,31 +339,6 @@ CYBOZU_TEST_AUTO(naive)
 		const TestSet& ts = g_testSetTbl[i];
 		printf("i=%d curve=%s\n", int(i), ts.name);
 		initPairing(ts.cp, g_mode);
-if(0){
-	G1 P(ts.g1.a, ts.g1.b);
-	G2 Q(Fp2(ts.g2.aa, ts.g2.ab), Fp2(ts.g2.ba, ts.g2.bb));
-	Fp12 z1, z2;
-	Fp6 x;
-	for (int i = 0; i < 12; i++) z1.getFp0()[i] = i * i + i + 3;
-	for (int i = 0; i < 6; i++) x.getFp0()[i] = i * i * i + i * 2 + 4;
-	z2 = z1;
-	Fp12 t;
-	mcl::util::convertFp6toFp12(t, x);
-	z1 *= t;
-	BN::mul_025(z2, x);
-	for (int i = 0; i < 12; i++) {
-		printf("i=%d\n", i);
-		CYBOZU_TEST_EQUAL(z1.getFp0()[i], z2.getFp0()[i]);
-	}
-//	CYBOZU_BENCH_C("addLine", 100000, BN::addLine, z1.a, Q, Q, P);
-//	CYBOZU_BENCH_C("dblLine", 100000, BN::dblLine, z1.a, Q, P);
-BN::Fp2Dbl D;
-	CYBOZU_BENCH_C("Fp2Dbl::mulPre", 100000, BN::Fp2Dbl::mulPre, D, x.a, x.b);
-	CYBOZU_BENCH_C("Fp6mul_01", 1000000, BN::Fp6mul_01, x, x, x.a, x.b);
-	CYBOZU_BENCH_C("mul_025", 1000000, BN::mul_025, z2,z2.a);
-	CYBOZU_BENCH_C("mulSparse", 1000000, BN::mulSparse, z2,z2.a);
-	exit(1);
-}
 		const G1 P(ts.g1.a, ts.g1.b);
 		const G2 Q(Fp2(ts.g2.aa, ts.g2.ab), Fp2(ts.g2.ba, ts.g2.bb));
 #ifdef ONLY_BENCH