add mclBn{Fr,Fp}_setLittleEndianMod

3 files changed, 48 insertions, 0 deletions

diff --git a/include/mcl/bn.h b/include/mcl/bn.h
index 2ea72ac..ca26000 100644
--- a/include/mcl/bn.h
+++ b/include/mcl/bn.h
@@ -233,6 +233,13 @@ MCLBN_DLL_API void mclBnFr_setInt32(mclBnFr *y, int x);
 MCLBN_DLL_API int mclBnFr_setLittleEndian(mclBnFr *x, const void *buf, mclSize bufSize);
 MCLBN_DLL_API int mclBnFp_setLittleEndian(mclBnFp *x, const void *buf, mclSize bufSize);
 
+// set (buf mod r) to x
+// return 0 if bufSize <= (byte size of Fr * 2) else -1
+MCLBN_DLL_API int mclBnFr_setLittleEndianMod(mclBnFr *x, const void *buf, mclSize bufSize);
+// set (buf mod p) to x
+// return 0 if bufSize <= (byte size of Fp * 2) else -1
+MCLBN_DLL_API int mclBnFp_setLittleEndianMod(mclBnFp *x, const void *buf, mclSize bufSize);
+
 // return 1 if true and 0 otherwise
 MCLBN_DLL_API int mclBnFr_isValid(const mclBnFr *x);
 MCLBN_DLL_API int mclBnFr_isEqual(const mclBnFr *x, const mclBnFr *y);
diff --git a/include/mcl/impl/bn_c_impl.hpp b/include/mcl/impl/bn_c_impl.hpp
index ab63ec9..1852668 100644
--- a/include/mcl/impl/bn_c_impl.hpp
+++ b/include/mcl/impl/bn_c_impl.hpp
@@ -134,6 +134,12 @@ int mclBnFr_setLittleEndian(mclBnFr *x, const void *buf, mclSize bufSize)
 	cast(x)->setArrayMask((const char *)buf, bufSize);
 	return 0;
 }
+int mclBnFr_setLittleEndianMod(mclBnFr *x, const void *buf, mclSize bufSize)
+{
+	bool b;
+	cast(x)->setArray(&b, (const char *)buf, bufSize, mcl::fp::Mod);
+	return b ? 0 : -1;
+}
 mclSize mclBnFr_deserialize(mclBnFr *x, const void *buf, mclSize bufSize)
 {
 	return (mclSize)cast(x)->deserialize(buf, bufSize);
@@ -573,6 +579,12 @@ int mclBnFp_setLittleEndian(mclBnFp *x, const void *buf, mclSize bufSize)
 	return 0;
 }
 
+int mclBnFp_setLittleEndianMod(mclBnFp *x, const void *buf, mclSize bufSize)
+{
+	bool b;
+	cast(x)->setArray(&b, (const char *)buf, bufSize, mcl::fp::Mod);
+	return b ? 0 : -1;
+}
 int mclBnFp_isEqual(const mclBnFp *x, const mclBnFp *y)
 {
 	return *cast(x) == *cast(y);
diff --git a/test/bn_c_test.hpp b/test/bn_c_test.hpp
index 8631ef1..e9dc593 100644
--- a/test/bn_c_test.hpp
+++ b/test/bn_c_test.hpp
@@ -5,6 +5,7 @@
 #include <mcl/ecparam.hpp>
 #include <cybozu/test.hpp>
 #include <iostream>
+#include <gmpxx.h>
 
 template<size_t N>
 std::ostream& dump(std::ostream& os, const uint64_t (&x)[N])
@@ -594,6 +595,34 @@ CYBOZU_TEST_AUTO(Fp)
 	CYBOZU_TEST_ASSERT(mclBnFp_isEqual(&x1, &x2));
 }
 
+CYBOZU_TEST_AUTO(mod)
+{
+	{
+		// Fp
+		char buf[1024];
+		mclBn_getFieldOrder(buf, sizeof(buf));
+		mpz_class p(buf);
+		mpz_class x = mpz_class(1) << (mclBn_getFpByteSize() * 2);
+		mclBnFp y;
+		int ret = mclBnFp_setLittleEndianMod(&y, x.get_mpz_t()->_mp_d, x.get_mpz_t()->_mp_size * sizeof(void*));
+		CYBOZU_TEST_EQUAL(ret, 0);
+		mclBnFp_getStr(buf, sizeof(buf), &y, 10);
+		CYBOZU_TEST_EQUAL(mpz_class(buf), x % p);
+	}
+	{
+		// Fr
+		char buf[1024];
+		mclBn_getCurveOrder(buf, sizeof(buf));
+		mpz_class p(buf);
+		mpz_class x = mpz_class(1) << (mclBn_getFrByteSize() * 2);
+		mclBnFr y;
+		int ret = mclBnFr_setLittleEndianMod(&y, x.get_mpz_t()->_mp_d, x.get_mpz_t()->_mp_size * sizeof(void*));
+		CYBOZU_TEST_EQUAL(ret, 0);
+		mclBnFr_getStr(buf, sizeof(buf), &y, 10);
+		CYBOZU_TEST_EQUAL(mpz_class(buf), x % p);
+	}
+}
+
 CYBOZU_TEST_AUTO(Fp2)
 {
 	mclBnFp2 x1, x2;