Cleanup XTS mode

1 files changed, 16 insertions, 9 deletions

diff --git a/xts.cpp b/xts.cpp
index 8addd5fd..d123a745 100644
--- a/xts.cpp
+++ b/xts.cpp
@@ -63,7 +63,7 @@ inline void XorBuffer(byte *output, const byte *input, const byte *mask, size_t
     CRYPTOPP_ASSERT(count >= 16 && (count % 16 == 0));

 

 #if defined(CRYPTOPP_DISABLE_ASM)

-	xorbuf(output, input, mask, count);

+    xorbuf(output, input, mask, count);

 

 #elif defined(__SSE2__) || defined(_M_X64)

     for (size_t i=0; i<count; i+=16)

@@ -247,10 +247,9 @@ void XTS_ModeBase::ProcessData(byte *outString, const byte *inString, size_t len
 

     const unsigned int blockSize = GetBlockCipher().BlockSize();

     const size_t parallelSize = blockSize*ParallelBlocks;

-    size_t i = 0;

 

     // encrypt the data unit, optimal size at a time

-    for ( ; i+parallelSize<=length; i+=parallelSize)

+    while (length >= parallelSize)

     {

         // If this fires the GF_Double'ing below is not in sync

         CRYPTOPP_ASSERT(ParallelBlocks == 4);

@@ -261,29 +260,37 @@ void XTS_ModeBase::ProcessData(byte *outString, const byte *inString, size_t len
         GF_Double(m_xregister+3*blockSize, m_xregister+2*blockSize, blockSize);

 

         // merge the tweak into the input block

-        XorBuffer(m_xworkspace, inString+i, m_xregister, parallelSize);

+        XorBuffer(m_xworkspace, inString, m_xregister, parallelSize);

 

         // encrypt one block, merge the tweak into the output block

-        GetBlockCipher().AdvancedProcessBlocks(m_xworkspace, m_xregister, outString+i, parallelSize, BlockTransformation::BT_AllowParallel);

+        GetBlockCipher().AdvancedProcessBlocks(m_xworkspace, m_xregister, outString, parallelSize, BlockTransformation::BT_AllowParallel);

 

         // m_xregister[0] always points to the next tweak.

-        GF_Double(m_xregister+0, m_xregister+(ParallelBlocks-1)*blockSize, blockSize);

+        GF_Double(m_xregister+0, m_xregister+3*blockSize, blockSize);

+

+        inString += parallelSize;

+        outString += parallelSize;

+        length -= parallelSize;

     }

 

     // encrypt the data unit, blocksize at a time

-    for ( ; i<length; i+=blockSize)

+    while (length)

     {

         // merge the tweak into the input block

-        XorBuffer(m_xworkspace, inString+i, m_xregister, blockSize);

+        XorBuffer(m_xworkspace, inString, m_xregister, blockSize);

 

         // encrypt one block

         GetBlockCipher().ProcessBlock(m_xworkspace);

 

         // merge the tweak into the output block

-        XorBuffer(outString+i, m_xworkspace, m_xregister, blockSize);

+        XorBuffer(outString, m_xworkspace, m_xregister, blockSize);

 

         // Multiply T by alpha

         GF_Double(m_xregister, blockSize);

+

+        inString += blockSize;

+        outString += blockSize;

+        length -= blockSize;

     }

 }