add mclBn{Fp,Fr}_pow

herumi · Sep 10, 2024 · 66b8d9c · 66b8d9c
1 parent 6879251
commit 66b8d9c
Show file tree

Hide file tree

Showing 4 changed files with 105 additions and 0 deletions.
diff --git a/include/mcl/bn.h b/include/mcl/bn.h
@@ -378,6 +378,10 @@ MCLBN_DLL_API int mclBnFr_squareRoot(mclBnFr *y, const mclBnFr *x);
 MCLBN_DLL_API int mclBnFp_squareRoot(mclBnFp *y, const mclBnFp *x);
 MCLBN_DLL_API int mclBnFp2_squareRoot(mclBnFp2 *y, const mclBnFp2 *x);
 
+// z = x^y[0:ySize] : y[] is little endian
+// return 0 if ySize <= 64 (This value may be changed) else -1
+MCLBN_DLL_API int mclBnFr_pow(mclBnFr *z, const mclBnFr *x, const uint8_t *y, mclSize ySize);
+MCLBN_DLL_API int mclBnFp_pow(mclBnFp *z, const mclBnFp *x, const uint8_t *y, mclSize ySize);
 ////////////////////////////////////////////////
 // set zero
 MCLBN_DLL_API void mclBnG1_clear(mclBnG1 *x);

diff --git a/include/mcl/impl/bn_c_impl.hpp b/include/mcl/impl/bn_c_impl.hpp
@@ -883,3 +883,28 @@ int mclBnG1_getBasePoint(mclBnG1 *x)
 	return 0;
 }
 
+template<class F>
+static int F_pow(F& z, const F& x, const uint8_t *_y, mclSize ySize)
+{
+	if (ySize == 0) {
+		z = 1;
+		return 0;
+	}
+	const size_t maxSize = 64;
+	if (ySize > maxSize) return -1;
+	const size_t yN = maxSize / sizeof(mcl::Unit);
+	mcl::Unit y[yN];
+	if (!mcl::fp::convertArrayAsLE(y, yN, _y, ySize)) return -1;
+	mcl::fp::powUnit(z, x, y, yN);
+	return 0;
+}
+
+int mclBnFr_pow(mclBnFr *z, const mclBnFr *x, const uint8_t *y, mclSize ySize)
+{
+	return F_pow(*cast(z), *cast(x), y, ySize);
+}
+
+int mclBnFp_pow(mclBnFp *z, const mclBnFp *x, const uint8_t *y, mclSize ySize)
+{
+	return F_pow(*cast(z), *cast(x), y, ySize);
+}
diff --git a/include/mcl/operator.hpp b/include/mcl/operator.hpp
@@ -171,6 +171,10 @@ inline size_t argminWforPow(size_t size)
 template<class F>
 void powUnit(F& z, const F& x, const Unit *y, size_t yn)
 {
+	if (yn == 0) {
+		z = 1;
+		return;
+	}
 	yn = bint::getRealSize(y, yn);
 	if (yn == 1) {
 		switch (y[0]) {

diff --git a/test/bn_c_test.hpp b/test/bn_c_test.hpp
@@ -138,6 +138,78 @@ CYBOZU_TEST_AUTO(Fr)
 	CYBOZU_TEST_EQUAL(mclBnFr_cmp(&y, &x), 1);
 }
 
+CYBOZU_TEST_AUTO(Fr_pow)
+{
+	mclBnFr x, z1, z2;
+	const char *s = "123456789123456789123";
+	CYBOZU_TEST_ASSERT(!mclBnFr_setStr(&x, s, strlen(s), 10));
+	mclBnFr_setInt(&z1, 1);
+	// small pow
+	for (uint8_t i = 0; i < 100; i++) {
+		CYBOZU_TEST_ASSERT(!mclBnFr_pow(&z2, &x, &i, 1));
+		CYBOZU_TEST_ASSERT(mclBnFr_isEqual(&z1, &z2));
+		mclBnFr_mul(&z1, &z1, &x);
+	}
+	mclBnFr one, negOne;
+	mclBnFr_setInt(&one, 1);
+	mclBnFr_setInt(&negOne, -1); // p-1
+	// large pow
+	mclBnFr y = z1;
+	for (int i = 0; i < 100; i++) {
+		uint8_t yBuf[64];
+		size_t yn = mclBnFr_getLittleEndian(yBuf, sizeof(yBuf), &y);
+		CYBOZU_TEST_ASSERT(yn > 0);
+		mclBnFr_pow(&z1, &x, yBuf, yn); // z1 = x^{y}
+		mclBnFr_sub(&y, &negOne, &y); // y = p-1-y
+		yn = mclBnFr_getLittleEndian(yBuf, sizeof(yBuf), &y);
+		mclBnFr_pow(&z2, &x, yBuf, yn); // z2 = x^{p-1-y}
+		mclBnFr_mul(&z1, &z1, &z2);
+		// x^{p-1} = 1 mod p
+		CYBOZU_TEST_ASSERT(mclBnFr_isEqual(&z1, &one));
+	}
+	// err
+	{
+		uint8_t buf[100] = {};
+		CYBOZU_TEST_ASSERT(mclBnFr_pow(&x, &x, buf, sizeof(buf)) < 0);
+	}
+}
+
+CYBOZU_TEST_AUTO(Fp_pow)
+{
+	mclBnFp x, z1, z2;
+	const char *s = "123456789123456789123";
+	CYBOZU_TEST_ASSERT(!mclBnFp_setStr(&x, s, strlen(s), 10));
+	mclBnFp_setInt(&z1, 1);
+	// small pow
+	for (uint8_t i = 0; i < 100; i++) {
+		CYBOZU_TEST_ASSERT(!mclBnFp_pow(&z2, &x, &i, 1));
+		CYBOZU_TEST_ASSERT(mclBnFp_isEqual(&z1, &z2));
+		mclBnFp_mul(&z1, &z1, &x);
+	}
+	mclBnFp one, negOne;
+	mclBnFp_setInt(&one, 1);
+	mclBnFp_setInt(&negOne, -1); // p-1
+	// large pow
+	mclBnFp y = z1;
+	for (int i = 0; i < 100; i++) {
+		uint8_t yBuf[64];
+		size_t yn = mclBnFp_getLittleEndian(yBuf, sizeof(yBuf), &y);
+		CYBOZU_TEST_ASSERT(yn > 0);
+		mclBnFp_pow(&z1, &x, yBuf, yn); // z1 = x^{y}
+		mclBnFp_sub(&y, &negOne, &y); // y = p-1-y
+		yn = mclBnFp_getLittleEndian(yBuf, sizeof(yBuf), &y);
+		mclBnFp_pow(&z2, &x, yBuf, yn); // z2 = x^{p-1-y}
+		mclBnFp_mul(&z1, &z1, &z2);
+		// x^{p-1} = 1 mod p
+		CYBOZU_TEST_ASSERT(mclBnFp_isEqual(&z1, &one));
+	}
+	// err
+	{
+		uint8_t buf[100] = {};
+		CYBOZU_TEST_ASSERT(mclBnFp_pow(&x, &x, buf, sizeof(buf)) < 0);
+	}
+}
+
 void G1test()
 {
 	mclBnG1 x, y, z;