From 04b13fb039ddb74a098c5c46cbde606d29f74cbe Mon Sep 17 00:00:00 2001
From: MITSUNARI Shigeo <herumi@nifty.com>
Date: Mon, 3 May 2021 14:51:54 +0900
Subject: [PATCH] refactor setArrayMask and requires unsigned

---
 include/mcl/fp.hpp             | 48 ++++++++++++++++++++--------------
 include/mcl/impl/bn_c_impl.hpp |  6 ++---
 test/fp_test.cpp               |  6 ++---
 3 files changed, 35 insertions(+), 25 deletions(-)

diff --git a/include/mcl/fp.hpp b/include/mcl/fp.hpp
index 88515d4..4e45814 100644
--- a/include/mcl/fp.hpp
+++ b/include/mcl/fp.hpp
@@ -339,24 +339,44 @@ public:
 		cybozu::write(pb, os, buf + sizeof(buf) - len, len);
 	}
 	/*
-		set array x as little endian
+		treat x as little endian
+		if x >= p then error
 	*/
 	template<class S>
-	void setArray_(bool *pb, const S *x, size_t n, mcl::fp::MaskMode mode = fp::NoMask)
-	{
-		*pb = fp::copyAndMask(v_, x, sizeof(S) * n, op_, mode);
-		toMont();
-	}
-	template<class S>
 	void setArray(bool *pb, const S *x, size_t n)
 	{
-		if (!fp::convertArrayAsLE(v_, op_.N, x, n) || fp::isGreaterOrEqualArray(v_, op_.p, op_.N)) {
+		if (!fp::convertArrayAsLE(v_, op_.N, x, n)) {
+			*pb = false;
+			return;
+		}
+		if (fp::isGreaterOrEqualArray(v_, op_.p, op_.N)) {
 			*pb = false;
 			return;
 		}
 		*pb = true;
 		toMont();
 	}
+	/*
+		treat x as little endian
+		x &= (1 << bitLen) = 1
+		x &= (1 << (bitLen - 1)) - 1 if x >= p
+	*/
+	template<class S>
+	void setArrayMask(const S *x, size_t n)
+	{
+		const size_t dstByte = sizeof(fp::Unit) * op_.N;
+		if (sizeof(S) * n > dstByte) {
+			n = dstByte / sizeof(S);
+		}
+		bool b = fp::convertArrayAsLE(v_, op_.N, x, n);
+		assert(b);
+		(void)b;
+		fp::maskArray(v_, op_.N, op_.bitSize);
+		if (fp::isGreaterOrEqualArray(v_, op_.p, op_.N)) {
+			fp::maskArray(v_, op_.N, op_.bitSize - 1);
+		}
+		toMont();
+	}
 	/*
 		set (x as little endian) % p
 		error if size of x >= sizeof(Fp) * 2
@@ -380,16 +400,6 @@ public:
 		if (!*pb) return;
 		toMont();
 	}
-
-	/*
-		mask x with (1 << (bitLen - 1)) - 1 if x >= p
-	*/
-	template<class S>
-	void setArrayMask(const S *x, size_t n)
-	{
-		fp::copyAndMask(v_, x, sizeof(S) * n, op_, fp::SmallMask);
-		toMont();
-	}
 	void getBlock(fp::Block& b) const
 	{
 		b.n = op_.N;
@@ -488,7 +498,7 @@ public:
 	*/
 	void setHashOf(const void *msg, size_t msgSize)
 	{
-		char buf[MCL_MAX_HASH_BIT_SIZE / 8];
+		uint8_t buf[MCL_MAX_HASH_BIT_SIZE / 8];
 		uint32_t size = op_.hash(buf, static_cast<uint32_t>(sizeof(buf)), msg, static_cast<uint32_t>(msgSize));
 		setArrayMask(buf, size);
 	}
diff --git a/include/mcl/impl/bn_c_impl.hpp b/include/mcl/impl/bn_c_impl.hpp
index b63c9b8..4f930e2 100644
--- a/include/mcl/impl/bn_c_impl.hpp
+++ b/include/mcl/impl/bn_c_impl.hpp
@@ -159,7 +159,7 @@ int mclBnFr_setStr(mclBnFr *x, const char *buf, mclSize bufSize, int ioMode)
 }
 int mclBnFr_setLittleEndian(mclBnFr *x, const void *buf, mclSize bufSize)
 {
-	cast(x)->setArrayMask((const char *)buf, bufSize);
+	cast(x)->setArrayMask((const uint8_t *)buf, bufSize);
 	return 0;
 }
 int mclBnFr_setBigEndianMod(mclBnFr *x, const void *buf, mclSize bufSize)
@@ -176,7 +176,7 @@ mclSize mclBnFr_getLittleEndian(void *buf, mclSize maxBufSize, const mclBnFr *x)
 int mclBnFr_setLittleEndianMod(mclBnFr *x, const void *buf, mclSize bufSize)
 {
 	bool b;
-	cast(x)->setArrayMod(&b, (const char *)buf, bufSize);
+	cast(x)->setArrayMod(&b, (const uint8_t *)buf, bufSize);
 	return b ? 0 : -1;
 }
 mclSize mclBnFr_deserialize(mclBnFr *x, const void *buf, mclSize bufSize)
@@ -729,7 +729,7 @@ void mclBnFp_clear(mclBnFp *x)
 
 int mclBnFp_setLittleEndian(mclBnFp *x, const void *buf, mclSize bufSize)
 {
-	cast(x)->setArrayMask((const char *)buf, bufSize);
+	cast(x)->setArrayMask((const uint8_t *)buf, bufSize);
 	return 0;
 }
 
diff --git a/test/fp_test.cpp b/test/fp_test.cpp
index c863a66..496c8a0 100644
--- a/test/fp_test.cpp
+++ b/test/fp_test.cpp
@@ -547,11 +547,11 @@ void setArrayTest2(mcl::fp::Mode mode)
 
 void setArrayMaskTest1()
 {
-	char b1[] = { 0x56, 0x34, 0x12 };
+	uint8_t b1[] = { 0x56, 0x34, 0x12 };
 	Fp x;
 	x.setArrayMask(b1, 3);
 	CYBOZU_TEST_EQUAL(x, 0x123456);
-	int b2[] = { 0x12, 0x34 };
+	uint32_t b2[] = { 0x12, 0x34 };
 	x.setArrayMask(b2, 2);
 	CYBOZU_TEST_EQUAL(x, Fp("0x3400000012"));
 }
@@ -811,7 +811,7 @@ void setHashOfTest()
 			digest = cybozu::Sha512().digest(msgTbl[i]);
 		}
 		Fp x, y;
-		x.setArrayMask(digest.c_str(), digest.size());
+		x.setArrayMask((const uint8_t*)digest.c_str(), digest.size());
 		y.setHashOf(msgTbl[i]);
 		CYBOZU_TEST_EQUAL(x, y);
 	}