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// strciphr.cpp - written and placed in the public domain by Wei Dai
#include "pch.h"
#ifndef CRYPTOPP_IMPORTS
#include "strciphr.h"
NAMESPACE_BEGIN(CryptoPP)
template <class S>
byte AdditiveCipherTemplate<S>::GenerateByte()
{
PolicyInterface &policy = AccessPolicy();
if (m_leftOver == 0)
{
policy.WriteKeystream(m_buffer, policy.GetIterationsToBuffer());
m_leftOver = policy.GetBytesPerIteration();
}
return *(KeystreamBufferEnd()-m_leftOver--);
}
template <class S>
inline void AdditiveCipherTemplate<S>::ProcessData(byte *outString, const byte *inString, unsigned int length)
{
if (m_leftOver > 0)
{
unsigned int len = STDMIN(m_leftOver, length);
xorbuf(outString, inString, KeystreamBufferEnd()-m_leftOver, len);
length -= len;
m_leftOver -= len;
inString += len;
outString += len;
}
if (!length)
return;
assert(m_leftOver == 0);
PolicyInterface &policy = AccessPolicy();
unsigned int bytesPerIteration = policy.GetBytesPerIteration();
unsigned int alignment = policy.GetAlignment();
if (policy.CanOperateKeystream() && length >= bytesPerIteration && IsAlignedOn(outString, alignment))
{
if (IsAlignedOn(inString, alignment))
policy.OperateKeystream(XOR_KEYSTREAM, outString, inString, length / bytesPerIteration);
else
{
memcpy(outString, inString, length);
policy.OperateKeystream(XOR_KEYSTREAM_INPLACE, outString, outString, length / bytesPerIteration);
}
inString += length - length % bytesPerIteration;
outString += length - length % bytesPerIteration;
length %= bytesPerIteration;
if (!length)
return;
}
unsigned int bufferByteSize = GetBufferByteSize(policy);
unsigned int bufferIterations = policy.GetIterationsToBuffer();
while (length >= bufferByteSize)
{
policy.WriteKeystream(m_buffer, bufferIterations);
xorbuf(outString, inString, KeystreamBufferBegin(), bufferByteSize);
length -= bufferByteSize;
inString += bufferByteSize;
outString += bufferByteSize;
}
if (length > 0)
{
policy.WriteKeystream(m_buffer, bufferIterations);
xorbuf(outString, inString, KeystreamBufferBegin(), length);
m_leftOver = bytesPerIteration - length;
}
}
template <class S>
void AdditiveCipherTemplate<S>::Resynchronize(const byte *iv)
{
PolicyInterface &policy = AccessPolicy();
m_leftOver = 0;
m_buffer.New(GetBufferByteSize(policy));
policy.CipherResynchronize(m_buffer, iv);
}
template <class BASE>
void AdditiveCipherTemplate<BASE>::Seek(lword position)
{
PolicyInterface &policy = AccessPolicy();
unsigned int bytesPerIteration = policy.GetBytesPerIteration();
policy.SeekToIteration(position / bytesPerIteration);
position %= bytesPerIteration;
if (position > 0)
{
policy.WriteKeystream(m_buffer, 1);
m_leftOver = bytesPerIteration - (unsigned int)position;
}
else
m_leftOver = 0;
}
template <class BASE>
void CFB_CipherTemplate<BASE>::Resynchronize(const byte *iv)
{
PolicyInterface &policy = AccessPolicy();
policy.CipherResynchronize(iv);
m_leftOver = policy.GetBytesPerIteration();
}
template <class BASE>
void CFB_CipherTemplate<BASE>::ProcessData(byte *outString, const byte *inString, unsigned int length)
{
PolicyInterface &policy = AccessPolicy();
unsigned int bytesPerIteration = policy.GetBytesPerIteration();
unsigned int alignment = policy.GetAlignment();
byte *reg = policy.GetRegisterBegin();
if (m_leftOver)
{
unsigned int len = STDMIN(m_leftOver, length);
CombineMessageAndShiftRegister(outString, reg + bytesPerIteration - m_leftOver, inString, len);
m_leftOver -= len;
length -= len;
inString += len;
outString += len;
}
if (!length)
return;
assert(m_leftOver == 0);
if (policy.CanIterate() && length >= bytesPerIteration && IsAlignedOn(outString, alignment))
{
if (IsAlignedOn(inString, alignment))
policy.Iterate(outString, inString, GetCipherDir(*this), length / bytesPerIteration);
else
{
memcpy(outString, inString, length);
policy.Iterate(outString, outString, GetCipherDir(*this), length / bytesPerIteration);
}
inString += length - length % bytesPerIteration;
outString += length - length % bytesPerIteration;
length %= bytesPerIteration;
}
while (length >= bytesPerIteration)
{
policy.TransformRegister();
CombineMessageAndShiftRegister(outString, reg, inString, bytesPerIteration);
length -= bytesPerIteration;
inString += bytesPerIteration;
outString += bytesPerIteration;
}
if (length > 0)
{
policy.TransformRegister();
CombineMessageAndShiftRegister(outString, reg, inString, length);
m_leftOver = bytesPerIteration - length;
}
}
template <class BASE>
void CFB_EncryptionTemplate<BASE>::CombineMessageAndShiftRegister(byte *output, byte *reg, const byte *message, unsigned int length)
{
xorbuf(reg, message, length);
memcpy(output, reg, length);
}
template <class BASE>
void CFB_DecryptionTemplate<BASE>::CombineMessageAndShiftRegister(byte *output, byte *reg, const byte *message, unsigned int length)
{
for (unsigned int i=0; i<length; i++)
{
byte b = message[i];
output[i] = reg[i] ^ b;
reg[i] = b;
}
}
NAMESPACE_END
#endif
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