/*
Derived from source code of TrueCrypt 7.1a, which is
Copyri/*
Copyright (c) 2008-2010 TrueCrypt Developers Association. All rights reserved.
Governed by the TrueCrypt License 3.0 the full text of which is contained in
the file License.txt included in TrueCrypt binary and source code distribution
packages.
*/
#include "EncryptionModeXTS.h"
#include "Common/Crypto.h"
namespace VeraCrypt
{
void EncryptionModeXTS::Encrypt (byte *data, uint64 length) const
{
EncryptBuffer (data, length, 0);
}
void EncryptionModeXTS::EncryptBuffer (byte *data, uint64 length, uint64 startDataUnitNo) const
{
if_debug (ValidateState());
CipherList::const_iterator iSecondaryCipher = SecondaryCiphers.begin();
for (CipherList::const_iterator iCipher = Ciphers.begin(); iCipher != Ciphers.end(); ++iCipher)
{
EncryptBufferXTS (**iCipher, **iSecondaryCipher, data, length, startDataUnitNo, 0);
++iSecondaryCipher;
}
assert (iSecondaryCipher == SecondaryCiphers.end());
}
void EncryptionModeXTS::EncryptBufferXTS (const Cipher &cipher, const Cipher &secondaryCipher, byte *buffer, uint64 length, uint64 startDataUnitNo, unsigned int startCipherBlockNo) const
{
byte finalCarry;
byte whiteningValues [ENCRYPTION_DATA_UNIT_SIZE];
byte whiteningValue [BYTES_PER_XTS_BLOCK];
byte byteBufUnitNo [BYTES_PER_XTS_BLOCK];
uint64 *whiteningValuesPtr64 = (uint64 *) whiteningValues;
uint64 *whiteningValuePtr64 = (uint64 *) whiteningValue;
uint64 *bufPtr = (uint64 *) buffer;
uint64 *dataUnitBufPtr;
unsigned int startBlock = startCipherBlockNo, endBlock, block;
uint64 *const finalInt64WhiteningValuesPtr = whiteningValuesPtr64 + sizeof (whiteningValues) / sizeof (*whiteningValuesPtr64) - 1;
uint64 blockCount, dataUnitNo;
startDataUnitNo += SectorOffset;
/* The encrypted data unit number (i.e. the resultant ciphertext block) is to be multiplied in the
finite field GF(2^128) by j-th power of n, where j is the sequential plaintext/ciphertext block
number and n is 2, a primitive element of GF(2^128). This can be (and is) simplified and implemented
as a left shift of the preceding whitening value by one bit (with carry propagating). In addition, if
the shift of the highest byte results in a carry, 135 is XORed into the lowest byte. The value 135 is
derived from the modulus of the Galois Field (x^128+x^7+x^2+x+1). */
// Convert the 64-bit data unit number into a little-endian 16-byte array.
// Note that as we are converting a 64-bit number into a 16-byte array we can always zero the last 8 bytes.
dataUnitNo = startDataUnitNo;
*((uint64 *) byteBufUnitNo) = Endian::Little (dataUnitNo);
*((uint64 *) byteBufUnitNo + 1) = 0;
if (length % BYTES_PER_XTS_BLOCK)
TC_THROW_FATAL_EXCEPTION;
blockCount = length / BYTES_PER_XTS_BLOCK;
// Process all blocks in the buffer
while (blockCount > 0)
{
if (blockCount < BLOCKS_PER_XTS_DATA_UNIT)
endBlock = startBlock + (unsigned int) blockCount;
else
endBlock = BLOCKS_PER_XTS_DATA_UNIT;
whiteningValuesPtr64 = finalInt64WhiteningValuesPtr;
whiteningValuePtr64 = (uint64 *) whiteningValue;
// Encrypt the data unit number using the secondary key (in order to generate the first
// whitening value for this data unit)
*whiteningValuePtr64 = *((uint64 *) byteBufUnitNo);
*(whiteningValuePtr64 + 1) = 0;
secondaryCipher.EncryptBlock (whiteningValue);
// Generate subsequent whitening values for blocks in this data unit. Note that all generated 128-bit
// whitening values are stored in memory as a sequence of 64-bit integers in reverse order.
for (block = 0; block < endBlock; block++)
{
if (block >= startBlock)
{
*whiteningValuesPtr64-- = *whiteningValuePtr64++;
*whiteningValuesPtr64-- = *whiteningValuePtr64;
}
else
whiteningValuePtr64++;
// Derive the next whitening value
#if BYTE_ORDER == LITTLE_ENDIAN
// Little-endian platforms
finalCarry =
(*whiteningValuePtr64 & 0x8000000000000000ULL) ?
135 : 0;
*whiteningValuePtr64-- <<= 1;
if (*whiteningValuePtr64 & 0x8000000000000000ULL)
*(whiteningValuePtr64 + 1) |= 1;
*whiteningValuePtr64 <<= 1;
#else
// Big-endian platforms
finalCarry =
(*whiteningValuePtr64 & 0x80) ?
135 : 0;
*whiteningValuePtr64 = Endian::Little (Endian::Little (*whiteningValuePtr64) << 1);
whiteningValuePtr64--;
if (*whiteningValuePtr64 & 0x80)
*(whiteningValuePtr64 + 1) |= 0x0100000000000000ULL;
*whiteningValuePtr64 = Endian::Little (Endian::Little (*whiteningValuePtr64) << 1);
#endif
whiteningValue[0] ^= finalCarry;
}
dataUnitBufPtr = bufPtr;
whiteningValuesPtr64 = finalInt64WhiteningValuesPtr;
// Encrypt all blocks in this data unit
for (block = startBlock; block < endBlock; block++)
{
// Pre-whitening
*bufPtr++ ^= *whiteningValuesPtr64--;
*bufPtr++ ^= *whiteningValuesPtr64--;
}
// Actual encryption
cipher.EncryptBlocks ((byte *) dataUnitBufPtr, endBlock - startBlock);
bufPtr = dataUnitBufPtr;
whiteningValuesPtr64 = finalInt64WhiteningValuesPtr;
for (block = startBlock; block < endBlock; block++)
{
// Post-whitening
*bufPtr++ ^= *whiteningValuesPtr64--;
*bufPtr++ ^= *whiteningValuesPtr64--;
}
blockCount -= endBlock - startBlock;
startBlock = 0;
dataUnitNo++;
*((uint64 *) byteBufUnitNo) = Endian::Little (dataUnitNo);
}
FAST_ERASE64 (whiteningValue, sizeof (whiteningValue));
FAST_ERASE64 (whiteningValues, sizeof (whiteningValues));
}
void EncryptionModeXTS::EncryptSectorsCurrentThread (byte *data, uint64 sectorIndex, uint64 sectorCount, size_t sectorSize) const
{
EncryptBuffer (data, sectorCount * sectorSize, sectorIndex * sectorSize / ENCRYPTION_DATA_UNIT_SIZE);
}
size_t EncryptionModeXTS::GetKeySize () const
{
if (Ciphers.empty())
throw NotInitialized (SRC_POS);
size_t keySize = 0;
foreach_ref (const Cipher &cipher, SecondaryCiphers)
{
keySize += cipher.GetKeySize();
}
return keySize;
}
void EncryptionModeXTS::Decrypt (byte *data, uint64 length) const
{
DecryptBuffer (data, length, 0);
}
void EncryptionModeXTS::DecryptBuffer (byte *data, uint64 length, uint64 startDataUnitNo) const
{
if_debug (ValidateState());
CipherList::const_iterator iSecondaryCipher = SecondaryCiphers.end();
for (CipherList::const_reverse_iterator iCipher = Ciphers.rbegin(); iCipher != Ciphers.rend(); ++iCipher)
{
--iSecondaryCipher;
DecryptBufferXTS (**iCipher, **iSecondaryCipher, data, length, startDataUnitNo, 0);
}
assert (iSecondaryCipher == SecondaryCiphers.begin());
}
void EncryptionModeXTS::DecryptBufferXTS (const Cipher &cipher, const Cipher &secondaryCipher, byte *buffer, uint64 length, uint64 startDataUnitNo, unsigned int startCipherBlockNo) const
{
byte finalCarry;
byte whiteningValues [ENCRYPTION_DATA_UNIT_SIZE];
byte whiteningValue [BYTES_PER_XTS_BLOCK];
byte byteBufUnitNo [BYTES_PER_XTS_BLOCK];
uint64 *whiteningValuesPtr64 = (uint64 *) whiteningValues;
uint64 *whiteningValuePtr64 = (uint64 *) whiteningValue;
uint64 *bufPtr = (uint64 *) buffer;
uint64 *dataUnitBufPtr;
unsigned int startBlock = startCipherBlockNo, endBlock, block;
uint64 *const finalInt64WhiteningValuesPtr = whiteningValuesPtr64 + sizeof (whiteningValues) / sizeof (*whiteningValuesPtr64) - 1;
uint64 blockCount, dataUnitNo;
startDataUnitNo += SectorOffset;
// Convert the 64-bit data unit number into a little-endian 16-byte array.
// Note that as we are converting a 64-bit number into a 16-byte array we can always zero the last 8 bytes.
dataUnitNo = startDataUnitNo;
*((uint64 *) byteBufUnitNo) = Endian::Little (dataUnitNo);
*((uint64 *) byteBufUnitNo + 1) = 0;
if (length % BYTES_PER_XTS_BLOCK)
TC_THROW_FATAL_EXCEPTION;
blockCount = length / BYTES_PER_XTS_BLOCK;
// Process all blocks in the buffer
while (blockCount > 0)
{
if (blockCount < BLOCKS_PER_XTS_DATA_UNIT)
endBlock = startBlock + (unsigned int) blockCount;
else
endBlock = BLOCKS_PER_XTS_DATA_UNIT;
whiteningValuesPtr64 = finalInt64WhiteningValuesPtr;
whiteningValuePtr64 = (uint64 *) whiteningValue;
// Encrypt the data unit number using the secondary key (in order to generate the first
// whitening value for this data unit)
*whiteningValuePtr64 = *((uint64 *) byteBufUnitNo);
*(whiteningValuePtr64 + 1) = 0;
secondaryCipher.EncryptBlock (whiteningValue);
// Generate subsequent whitening values for blocks in this data unit. Note that all generated 128-bit
// whitening values are stored in memory as a sequence of 64-bit integers in reverse order.
for (block = 0; block < endBlock; block++)
{
if (block >= startBlock)
{
*whiteningValuesPtr64-- = *whiteningValuePtr64++;
*whiteningValuesPtr64-- = *whiteningValuePtr64;
}
else
whiteningValuePtr64++;
// Derive the next whitening value
#if BYTE_ORDER == LITTLE_ENDIAN
// Little-endian platforms
finalCarry =
(*whiteningValuePtr64 & 0x8000000000000000ULL) ?
135 : 0;
*whiteningValuePtr64-- <<= 1;
if (*whiteningValuePtr64 & 0x8000000000000000ULL)
*(whiteningValuePtr64 + 1) |= 1;
*whiteningValuePtr64 <<= 1;
#else
// Big-endian platforms
finalCarry =
(*whiteningValuePtr64 & 0x80) ?
135 : 0;
*whiteningValuePtr64 = Endian::Little (Endian::Little (*whiteningValuePtr64) << 1);
whiteningValuePtr64--;
if (*whiteningValuePtr64 & 0x80)
*(whiteningValuePtr64 + 1) |= 0x0100000000000000ULL;
*whiteningValuePtr64 = Endian::Little (Endian::Little (*whiteningValuePtr64) << 1);
#endif
whiteningValue[0] ^= finalCarry;
}
dataUnitBufPtr = bufPtr;
whiteningValuesPtr64 = finalInt64WhiteningValuesPtr;
// Decrypt blocks in this data unit
for (block = startBlock; block < endBlock; block++)
{
*bufPtr++ ^= *whiteningValuesPtr64--;
*bufPtr++ ^= *whiteningValuesPtr64--;
}
cipher.DecryptBlocks ((byte *) dataUnitBufPtr, endBlock - startBlock);
bufPtr = dataUnitBufPtr;
whiteningValuesPtr64 = finalInt64WhiteningValuesPtr;
for (block = startBlock; block < endBlock; block++)
{
*bufPtr++ ^= *whiteningValuesPtr64--;
*bufPtr++ ^= *whiteningValuesPtr64--;
}
blockCount -= endBlock - startBlock;
startBlock = 0;
dataUnitNo++;
*((uint64 *) byteBufUnitNo) = Endian::Little (dataUnitNo);
}
FAST_ERASE64 (whiteningValue, sizeof (whiteningValue));
FAST_ERASE64 (whiteningValues, sizeof (whiteningValues));
}
void EncryptionModeXTS::DecryptSectorsCurrentThread (byte *data, uint64 sectorIndex, uint64 sectorCount, size_t sectorSize) const
{
DecryptBuffer (data, sectorCount * sectorSize, sectorIndex * sectorSize / ENCRYPTION_DATA_UNIT_SIZE);
}
void EncryptionModeXTS::SetCiphers (const CipherList &ciphers)
{
EncryptionMode::SetCiphers (ciphers);
SecondaryCiphers.clear();
foreach_ref (const Cipher &cipher, ciphers)
{
SecondaryCiphers.push_back (cipher.GetNew());
}
if (SecondaryKey.Size() > 0)
SetSecondaryCipherKeys();
}
void EncryptionModeXTS::SetKey (const ConstBufferPtr &key)
{
SecondaryKey.Allocate (key.Size());
SecondaryKey.CopyFrom (key);
if (!SecondaryCiphers.empty())
SetSecondaryCipherKeys();
}
void EncryptionModeXTS::SetSecondaryCipherKeys ()
{
size_t keyOffset = 0;
foreach_ref (Cipher &cipher, SecondaryCiphers)
{
cipher.SetKey (SecondaryKey.GetRange (keyOffset, cipher.GetKeySize()));
keyOffset += cipher.GetKeySize();
}
KeySet = true;
}
}
