1 files changed, 122 insertions, 0 deletions
diff --git a/CryptoPP/cmac.cpp b/CryptoPP/cmac.cpp
new file mode 100644
index 000000000..e8fa6fea6
--- /dev/null
+++ b/CryptoPP/cmac.cpp
@@ -0,0 +1,122 @@
+// cmac.cpp - written and placed in the public domain by Wei Dai
+
+#include "pch.h"
+
+#ifndef CRYPTOPP_IMPORTS
+
+#include "cmac.h"
+
+NAMESPACE_BEGIN(CryptoPP)
+
+static void MulU(byte *k, unsigned int length)
+{
+	byte carry = 0;
+
+	for (int i=length-1; i>=1; i-=2)
+	{
+		byte carry2 = k[i] >> 7;
+		k[i] += k[i] + carry;
+		carry = k[i-1] >> 7;
+		k[i-1] += k[i-1] + carry2;
+	}
+
+	if (carry)
+	{
+		switch (length)
+		{
+		case 8:
+			k[7] ^= 0x1b;
+			break;
+		case 16:
+			k[15] ^= 0x87;
+			break;
+		case 32:
+			k[30] ^= 4; 
+			k[31] ^= 0x23;
+			break;
+		default:
+			throw InvalidArgument("CMAC: " + IntToString(length) + " is not a supported cipher block size");
+		}
+	}
+}
+
+void CMAC_Base::UncheckedSetKey(const byte *key, unsigned int length, const NameValuePairs &params)
+{
+	BlockCipher &cipher = AccessCipher();
+	unsigned int blockSize = cipher.BlockSize();
+
+	cipher.SetKey(key, length, params);
+	m_reg.CleanNew(3*blockSize);
+	m_counter = 0;
+
+	cipher.ProcessBlock(m_reg, m_reg+blockSize);
+	MulU(m_reg+blockSize, blockSize);
+	memcpy(m_reg+2*blockSize, m_reg+blockSize, blockSize);
+	MulU(m_reg+2*blockSize, blockSize);
+}
+
+void CMAC_Base::Update(const byte *input, size_t length)
+{
+	if (!length)
+		return;
+
+	BlockCipher &cipher = AccessCipher();
+	unsigned int blockSize = cipher.BlockSize();
+
+	if (m_counter > 0)
+	{
+		unsigned int len = UnsignedMin(blockSize - m_counter, length);
+		xorbuf(m_reg+m_counter, input, len);
+		length -= len;
+		input += len;
+		m_counter += len;
+
+		if (m_counter == blockSize && length > 0)
+		{
+			cipher.ProcessBlock(m_reg);
+			m_counter = 0;
+		}
+	}
+
+	if (length > blockSize)
+	{
+		assert(m_counter == 0);
+		size_t leftOver = 1 + cipher.AdvancedProcessBlocks(m_reg, input, m_reg, length-1, BlockTransformation::BT_DontIncrementInOutPointers|BlockTransformation::BT_XorInput);
+		input += (length - leftOver);
+		length = leftOver;
+	}
+
+	if (length > 0)
+	{
+		assert(m_counter + length <= blockSize);
+		xorbuf(m_reg+m_counter, input, length);
+		m_counter += (unsigned int)length;
+	}
+
+	assert(m_counter > 0);
+}
+
+void CMAC_Base::TruncatedFinal(byte *mac, size_t size)
+{
+	ThrowIfInvalidTruncatedSize(size);
+
+	BlockCipher &cipher = AccessCipher();
+	unsigned int blockSize = cipher.BlockSize();
+
+	if (m_counter < blockSize)
+	{
+		m_reg[m_counter] ^= 0x80;
+		cipher.AdvancedProcessBlocks(m_reg, m_reg+2*blockSize, m_reg, blockSize, BlockTransformation::BT_DontIncrementInOutPointers|BlockTransformation::BT_XorInput);
+	}
+	else
+		cipher.AdvancedProcessBlocks(m_reg, m_reg+blockSize, m_reg, blockSize, BlockTransformation::BT_DontIncrementInOutPointers|BlockTransformation::BT_XorInput);
+
+	memcpy(mac, m_reg, size);
+
+	m_counter = 0;
+	memset(m_reg, 0, blockSize);
+}
+
+NAMESPACE_END
+
+#endif