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// modes.cpp - written and placed in the public domain by Wei Dai
#include "pch.h"
#ifndef CRYPTOPP_IMPORTS
#include "modes.h"
#ifndef NDEBUG
#include "des.h"
#endif
NAMESPACE_BEGIN(CryptoPP)
#ifndef NDEBUG
void Modes_TestInstantiations()
{
CFB_Mode<DES>::Encryption m0;
CFB_Mode<DES>::Decryption m1;
OFB_Mode<DES>::Encryption m2;
CTR_Mode<DES>::Encryption m3;
ECB_Mode<DES>::Encryption m4;
CBC_Mode<DES>::Encryption m5;
}
#endif
void CTR_ModePolicy::SeekToIteration(lword iterationCount)
{
int carry=0;
for (int i=BlockSize()-1; i>=0; i--)
{
unsigned int sum = m_register[i] + byte(iterationCount) + carry;
m_counterArray[i] = (byte) sum;
carry = sum >> 8;
iterationCount >>= 8;
}
}
inline void CTR_ModePolicy::ProcessMultipleBlocks(byte *output, const byte *input, size_t n)
{
unsigned int s = BlockSize(), j = 0;
for (unsigned int i=1; i<n; i++, j+=s)
IncrementCounterByOne(m_counterArray + j + s, m_counterArray + j, s);
m_cipher->ProcessAndXorMultipleBlocks(m_counterArray, input, output, n);
IncrementCounterByOne(m_counterArray, m_counterArray + s*(n-1), s);
}
void CTR_ModePolicy::OperateKeystream(KeystreamOperation operation, byte *output, const byte *input, size_t iterationCount)
{
assert(m_cipher->IsForwardTransformation()); // CTR mode needs the "encrypt" direction of the underlying block cipher, even to decrypt
unsigned int maxBlocks = m_cipher->OptimalNumberOfParallelBlocks();
if (maxBlocks == 1)
{
unsigned int sizeIncrement = BlockSize();
while (iterationCount)
{
m_cipher->ProcessAndXorBlock(m_counterArray, input, output);
IncrementCounterByOne(m_counterArray, sizeIncrement);
output += sizeIncrement;
input += sizeIncrement;
iterationCount -= 1;
}
}
else
{
unsigned int sizeIncrement = maxBlocks * BlockSize();
while (iterationCount >= maxBlocks)
{
ProcessMultipleBlocks(output, input, maxBlocks);
output += sizeIncrement;
input += sizeIncrement;
iterationCount -= maxBlocks;
}
if (iterationCount > 0)
ProcessMultipleBlocks(output, input, iterationCount);
}
}
void CTR_ModePolicy::CipherResynchronize(byte *keystreamBuffer, const byte *iv)
{
unsigned int s = BlockSize();
CopyOrZero(m_register, iv, s);
m_counterArray.New(s * m_cipher->OptimalNumberOfParallelBlocks());
CopyOrZero(m_counterArray, iv, s);
}
void BlockOrientedCipherModeBase::UncheckedSetKey(const byte *key, unsigned int length, const NameValuePairs ¶ms)
{
m_cipher->SetKey(key, length, params);
ResizeBuffers();
if (IsResynchronizable())
Resynchronize(GetIVAndThrowIfInvalid(params));
}
void BlockOrientedCipherModeBase::ProcessData(byte *outString, const byte *inString, size_t length)
{
if (!length)
return;
unsigned int s = BlockSize();
assert(length % s == 0);
if (!RequireAlignedInput() || IsAlignedOn(inString, m_cipher->BlockAlignment()))
ProcessBlocks(outString, inString, length / s);
else
{
do
{
memcpy(m_buffer, inString, s);
ProcessBlocks(outString, m_buffer, 1);
inString += s;
outString += s;
length -= s;
} while (length > 0);
}
}
void CBC_Encryption::ProcessBlocks(byte *outString, const byte *inString, size_t numberOfBlocks)
{
unsigned int blockSize = BlockSize();
xorbuf(m_register, inString, blockSize);
while (--numberOfBlocks)
{
m_cipher->ProcessBlock(m_register, outString);
inString += blockSize;
xorbuf(m_register, inString, outString, blockSize);
outString += blockSize;
}
m_cipher->ProcessBlock(m_register);
memcpy(outString, m_register, blockSize);
}
void CBC_CTS_Encryption::ProcessLastBlock(byte *outString, const byte *inString, size_t length)
{
if (length <= BlockSize())
{
if (!m_stolenIV)
throw InvalidArgument("CBC_Encryption: message is too short for ciphertext stealing");
// steal from IV
memcpy(outString, m_register, length);
outString = m_stolenIV;
}
else
{
// steal from next to last block
xorbuf(m_register, inString, BlockSize());
m_cipher->ProcessBlock(m_register);
inString += BlockSize();
length -= BlockSize();
memcpy(outString+BlockSize(), m_register, length);
}
// output last full ciphertext block
xorbuf(m_register, inString, length);
m_cipher->ProcessBlock(m_register);
memcpy(outString, m_register, BlockSize());
}
void CBC_Decryption::ProcessBlocks(byte *outString, const byte *inString, size_t numberOfBlocks)
{
unsigned int blockSize = BlockSize();
do
{
memcpy(m_temp, inString, blockSize); // make copy in case we're doing in place decryption
m_cipher->ProcessAndXorBlock(m_temp, m_register, outString);
m_register.swap(m_temp);
inString += blockSize;
outString += blockSize;
} while (--numberOfBlocks);
}
void CBC_CTS_Decryption::ProcessLastBlock(byte *outString, const byte *inString, size_t length)
{
const byte *pn, *pn1;
bool stealIV = length <= BlockSize();
if (stealIV)
{
pn = inString;
pn1 = m_register;
}
else
{
pn = inString + BlockSize();
pn1 = inString;
length -= BlockSize();
}
// decrypt last partial plaintext block
memcpy(m_temp, pn1, BlockSize());
m_cipher->ProcessBlock(m_temp);
xorbuf(m_temp, pn, length);
if (stealIV)
memcpy(outString, m_temp, length);
else
{
memcpy(outString+BlockSize(), m_temp, length);
// decrypt next to last plaintext block
memcpy(m_temp, pn, length);
m_cipher->ProcessBlock(m_temp);
xorbuf(outString, m_temp, m_register, BlockSize());
}
}
NAMESPACE_END
#endif
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