diff --git a/include/cybozu/sha2.hpp b/include/cybozu/sha2.hpp
index 1830936..335a897 100644
--- a/include/cybozu/sha2.hpp
+++ b/include/cybozu/sha2.hpp
@@ -145,24 +145,22 @@ inline uint64_t rot64(uint64_t x, int s)
 
 template<class T>
 struct Common {
-	void term(const char *buf, size_t bufSize)
+	void term(uint8_t *buf, size_t bufSize)
 	{
 		assert(bufSize < T::blockSize_);
 		T& self = static_cast<T&>(*this);
 		const uint64_t totalSize = self.totalSize_ + bufSize;
 
-		uint8_t last[T::blockSize_];
-		memcpy(last, buf, bufSize);
-		last[bufSize] = uint8_t(0x80); /* top bit = 1 */
-		memset(&last[bufSize + 1], 0, T::blockSize_ - bufSize - 1);
+		buf[bufSize] = uint8_t(0x80); /* top bit = 1 */
+		memset(&buf[bufSize + 1], 0, T::blockSize_ - bufSize - 1);
 		if (bufSize >= T::blockSize_ - T::msgLenByte_) {
-			self.round(reinterpret_cast<const char*>(last));
-			memset(last, 0, sizeof(last)); // clear stack
+			self.round(buf);
+			memset(buf, 0, T::blockSize_ - 8); // clear stack
 		}
-		cybozu::Set64bitAsBE(&last[T::blockSize_ - 8], totalSize * 8);
-		self.round(reinterpret_cast<const char*>(last));
+		cybozu::Set64bitAsBE(&buf[T::blockSize_ - 8], totalSize * 8);
+		self.round(buf);
 	}
-	void inner_update(const char *buf, size_t bufSize)
+	void inner_update(const uint8_t *buf, size_t bufSize)
 	{
 		T& self = static_cast<T&>(*this);
 		if (bufSize == 0) return;
@@ -203,15 +201,35 @@ private:
 	static const size_t msgLenByte_ = 8;
 	uint64_t totalSize_;
 	size_t roundBufSize_;
-	char roundBuf_[blockSize_];
+	uint8_t roundBuf_[blockSize_];
 	uint32_t h_[hSize_];
 	static const size_t outByteSize_ = hSize_ * sizeof(uint32_t);
 	const uint32_t *k_;
 
+	template<size_t i0, size_t i1, size_t i2, size_t i3, size_t i4, size_t i5, size_t i6, size_t i7>
+	void round1(uint32_t *s, uint32_t *w, int i)
+	{
+		using namespace sha2_local;
+		uint32_t e = s[i4];
+		uint32_t h = s[i7];
+		h += rot32(e, 6) ^ rot32(e, 11) ^ rot32(e, 25);
+		uint32_t f = s[i5];
+		uint32_t g = s[i6];
+		h += g ^ (e & (f ^ g));
+		h += k_[i];
+		h += w[i];
+		s[i3] += h;
+		uint32_t a = s[i0];
+		uint32_t b = s[i1];
+		uint32_t c = s[i2];
+		h += rot32(a, 2) ^ rot32(a, 13) ^ rot32(a, 22);
+		h += ((a | b) & c) | (a & b);
+		s[i7] = h;
+	}
 	/**
 		@param buf [in] buffer(64byte)
 	*/
-	void round(const char *buf)
+	void round(const uint8_t *buf)
 	{
 		using namespace sha2_local;
 		uint32_t w[64];
@@ -225,38 +243,23 @@ private:
 			uint32_t s1 = rot32(t, 17) ^ rot32(t, 19) ^ (t >> 10);
 			w[i] = w[i - 16] + s0 + w[i - 7] + s1;
 		}
-		uint32_t a = h_[0];
-		uint32_t b = h_[1];
-		uint32_t c = h_[2];
-		uint32_t d = h_[3];
-		uint32_t e = h_[4];
-		uint32_t f = h_[5];
-		uint32_t g = h_[6];
-		uint32_t h = h_[7];
-		for (int i = 0; i < 64; i++) {
-			uint32_t s1 = rot32(e, 6) ^ rot32(e, 11) ^ rot32(e, 25);
-			uint32_t ch = g ^ (e & (f ^ g));
-			uint32_t t1 = h + s1 + ch + k_[i] + w[i];
-			uint32_t s0 = rot32(a, 2) ^ rot32(a, 13) ^ rot32(a, 22);
-			uint32_t maj = ((a | b) & c) | (a & b);
-			uint32_t t2 = s0 + maj;
-			h = g;
-			g = f;
-			f = e;
-			e = d + t1;
-			d = c;
-			c = b;
-			b = a;
-			a = t1 + t2;
+		uint32_t s[8];
+		for (int i = 0; i < 8; i++) {
+			s[i] = h_[i];
+		}
+		for (int i = 0; i < 64; i += 8) {
+			round1<0, 1, 2, 3, 4, 5, 6, 7>(s, w, i + 0);
+			round1<7, 0, 1, 2, 3, 4, 5, 6>(s, w, i + 1);
+			round1<6, 7, 0, 1, 2, 3, 4, 5>(s, w, i + 2);
+			round1<5, 6, 7, 0, 1, 2, 3, 4>(s, w, i + 3);
+			round1<4, 5, 6, 7, 0, 1, 2, 3>(s, w, i + 4);
+			round1<3, 4, 5, 6, 7, 0, 1, 2>(s, w, i + 5);
+			round1<2, 3, 4, 5, 6, 7, 0, 1>(s, w, i + 6);
+			round1<1, 2, 3, 4, 5, 6, 7, 0>(s, w, i + 7);
+		}
+		for (int i = 0; i < 8; i++) {
+			h_[i] += s[i];
 		}
-		h_[0] += a;
-		h_[1] += b;
-		h_[2] += c;
-		h_[3] += d;
-		h_[4] += e;
-		h_[5] += f;
-		h_[6] += g;
-		h_[7] += h;
 		totalSize_ += blockSize_;
 	}
 public:
@@ -290,7 +293,7 @@ public:
 	}
 	void update(const void *buf, size_t bufSize)
 	{
-		inner_update(reinterpret_cast<const char*>(buf), bufSize);
+		inner_update(reinterpret_cast<const uint8_t*>(buf), bufSize);
 	}
 	size_t digest(void *md, size_t mdSize, const void *buf, size_t bufSize)
 	{
@@ -329,7 +332,7 @@ private:
 	static const size_t msgLenByte_ = 16;
 	uint64_t totalSize_;
 	size_t roundBufSize_;
-	char roundBuf_[blockSize_];
+	uint8_t roundBuf_[blockSize_];
 	uint64_t h_[hSize_];
 	static const size_t outByteSize_ = hSize_ * sizeof(uint64_t);
 	const uint64_t *k_;
@@ -359,7 +362,7 @@ private:
 	/**
 		@param buf [in] buffer(64byte)
 	*/
-	void round(const char *buf)
+	void round(const uint8_t *buf)
 	{
 		using namespace sha2_local;
 		uint64_t w[80];
@@ -431,7 +434,7 @@ public:
 	}
 	void update(const void *buf, size_t bufSize)
 	{
-		inner_update(reinterpret_cast<const char*>(buf), bufSize);
+		inner_update(reinterpret_cast<const uint8_t*>(buf), bufSize);
 	}
 	size_t digest(void *md, size_t mdSize, const void *buf, size_t bufSize)
 	{