Add XTS block cipher mode of operation (GH #891, PR #892)

1 files changed, 27 insertions, 6 deletions

diff --git a/cmac.cpp b/cmac.cpp
index ed56b10b..7a71236f 100644
--- a/cmac.cpp
+++ b/cmac.cpp
@@ -5,14 +5,17 @@
 #ifndef CRYPTOPP_IMPORTS

 

 #include "cmac.h"

+#include "misc.h"

 

-NAMESPACE_BEGIN(CryptoPP)

+ANONYMOUS_NAMESPACE_BEGIN

+

+using CryptoPP::byte;

+using CryptoPP::IsPowerOf2;

 

-static void MulU(byte *k, unsigned int length)

+void MulU(byte *k, unsigned int len)

 {

 	byte carry = 0;

-

-	for (int i=length-1; i>=1; i-=2)

+	for (int i=len-1; i>=1; i-=2)

 	{

 		byte carry2 = k[i] >> 7;

 		k[i] += k[i] + carry;

@@ -20,9 +23,22 @@ static void MulU(byte *k, unsigned int length)
 		k[i-1] += k[i-1] + carry2;

 	}

 

+#ifndef CRYPTOPP_CMAC_WIDE_BLOCK_CIPHERS

+	CRYPTOPP_ASSERT(len == 16);

+

+	if (carry)

+	{

+		k[15] ^= 0x87;

+		return;

+	}

+#else

+	CRYPTOPP_ASSERT(IsPowerOf2(len));

+	CRYPTOPP_ASSERT(len >= 8);

+	CRYPTOPP_ASSERT(len <= 128);

+

 	if (carry)

 	{

-		switch (length)

+		switch (len)

 		{

 		case 8:

 			k[7] ^= 0x1b;

@@ -50,11 +66,16 @@ static void MulU(byte *k, unsigned int length)
 			k[127] ^= 0x43;

 			break;

 		default:

-			throw InvalidArgument("CMAC: " + IntToString(length) + " is not a supported cipher block size");

+			CRYPTOPP_ASSERT(0);

 		}

 	}

+#endif  // CRYPTOPP_CMAC_WIDE_BLOCK_CIPHERS

 }

 

+ANONYMOUS_NAMESPACE_END

+

+NAMESPACE_BEGIN(CryptoPP)

+

 void CMAC_Base::UncheckedSetKey(const byte *key, unsigned int length, const NameValuePairs &params)

 {

 	BlockCipher &cipher = AccessCipher();