strciphr.cpp

// strciphr.cpp - originally written and placed in the public domain by Wei Dai.
 
#include "pch.h"
 
#ifndef CRYPTOPP_IMPORTS
 
#include "strciphr.h"
 
// Squash MS LNK4221 and libtool warnings
#ifndef CRYPTOPP_MANUALLY_INSTANTIATE_TEMPLATES
extern const char STRCIPHER_FNAME[] = __FILE__;
#endif
 
NAMESPACE_BEGIN(CryptoPP)
 
template <class S>
void AdditiveCipherTemplate<S>::UncheckedSetKey(const byte *key, unsigned int length, const NameValuePairs &params)
{
    PolicyInterface &policy = this->AccessPolicy();
    policy.CipherSetKey(params, key, length);
    m_leftOver = 0;
    unsigned int bufferByteSize = policy.CanOperateKeystream() ? GetBufferByteSize(policy) : RoundUpToMultipleOf(1024U, GetBufferByteSize(policy));
    m_buffer.New(bufferByteSize);
 
    if (this->IsResynchronizable())
    {
        size_t ivLength;
        const byte *iv = this->GetIVAndThrowIfInvalid(params, ivLength);
        policy.CipherResynchronize(m_buffer, iv, ivLength);
    }
}
 
template <class S>
void AdditiveCipherTemplate<S>::GenerateBlock(byte *outString, size_t length)
{
    if (m_leftOver > 0)
    {
        const size_t len = STDMIN(m_leftOver, length);
        std::memcpy(outString, PtrSub(KeystreamBufferEnd(), m_leftOver), len);
 
        length -= len; m_leftOver -= len;
        outString = PtrAdd(outString, len);
        if (!length) {return;}
    }
 
    PolicyInterface &policy = this->AccessPolicy();
    size_t bytesPerIteration = policy.GetBytesPerIteration();
 
    if (length >= bytesPerIteration)
    {
        const size_t iterations = length / bytesPerIteration;
        policy.WriteKeystream(outString, iterations);
        length -= iterations * bytesPerIteration;
        outString = PtrAdd(outString, iterations * bytesPerIteration);
    }
 
    if (length > 0)
    {
        size_t bufferByteSize = RoundUpToMultipleOf(length, bytesPerIteration);
        size_t bufferIterations = bufferByteSize / bytesPerIteration;
 
        policy.WriteKeystream(PtrSub(KeystreamBufferEnd(), bufferByteSize), bufferIterations);
        std::memcpy(outString, PtrSub(KeystreamBufferEnd(), bufferByteSize), length);
        m_leftOver = bufferByteSize - length;
    }
}
 
template <class S>
void AdditiveCipherTemplate<S>::ProcessData(byte *outString, const byte *inString, size_t length)
{
    CRYPTOPP_ASSERT(outString); CRYPTOPP_ASSERT(inString);
    CRYPTOPP_ASSERT(length % this->MandatoryBlockSize() == 0);
 
    PolicyInterface &policy = this->AccessPolicy();
    size_t bytesPerIteration = policy.GetBytesPerIteration();
 
    if (m_leftOver > 0)
    {
        const size_t len = STDMIN(m_leftOver, length);
        xorbuf(outString, inString, PtrSub(KeystreamBufferEnd(), m_leftOver), len);
 
        inString = PtrAdd(inString, len);
        outString = PtrAdd(outString, len);
        length -= len; m_leftOver -= len;
    }
 
    if (!length) { return; }
 
    const word32 alignment = policy.GetAlignment();
    const bool inAligned = IsAlignedOn(inString, alignment);
    const bool outAligned = IsAlignedOn(outString, alignment);
    CRYPTOPP_UNUSED(inAligned); CRYPTOPP_UNUSED(outAligned);
 
    if (policy.CanOperateKeystream() && length >= bytesPerIteration)
    {
        const size_t iterations = length / bytesPerIteration;
        KeystreamOperationFlags flags = static_cast<KeystreamOperationFlags>(
            (inAligned ? EnumToInt(INPUT_ALIGNED) : 0) | (outAligned ? EnumToInt(OUTPUT_ALIGNED) : 0));
        KeystreamOperation operation = KeystreamOperation(flags);
        policy.OperateKeystream(operation, outString, inString, iterations);
 
        inString = PtrAdd(inString, iterations * bytesPerIteration);
        outString = PtrAdd(outString, iterations * bytesPerIteration);
        length -= iterations * bytesPerIteration;
    }
 
    size_t bufferByteSize = m_buffer.size();
    size_t bufferIterations = bufferByteSize / bytesPerIteration;
 
    while (length >= bufferByteSize)
    {
        policy.WriteKeystream(m_buffer, bufferIterations);
        xorbuf(outString, inString, KeystreamBufferBegin(), bufferByteSize);
 
        inString = PtrAdd(inString, bufferByteSize);
        outString = PtrAdd(outString, bufferByteSize);
        length -= bufferByteSize;
    }
 
    if (length > 0)
    {
        bufferByteSize = RoundUpToMultipleOf(length, bytesPerIteration);
        bufferIterations = bufferByteSize / bytesPerIteration;
 
        policy.WriteKeystream(PtrSub(KeystreamBufferEnd(), bufferByteSize), bufferIterations);
        xorbuf(outString, inString, PtrSub(KeystreamBufferEnd(), bufferByteSize), length);
 
        m_leftOver = bufferByteSize - length;
    }
}
 
template <class S>
void AdditiveCipherTemplate<S>::Resynchronize(const byte *iv, int length)
{
    PolicyInterface &policy = this->AccessPolicy();
    m_leftOver = 0;
    m_buffer.New(GetBufferByteSize(policy));
    policy.CipherResynchronize(m_buffer, iv, this->ThrowIfInvalidIVLength(length));
}
 
template <class BASE>
void AdditiveCipherTemplate<BASE>::Seek(lword position)
{
    PolicyInterface &policy = this->AccessPolicy();
    unsigned int bytesPerIteration = policy.GetBytesPerIteration();
 
    policy.SeekToIteration(position / bytesPerIteration);
    position %= bytesPerIteration;
 
    if (position > 0)
    {
        policy.WriteKeystream(PtrSub(KeystreamBufferEnd(), bytesPerIteration), 1);
        m_leftOver = bytesPerIteration - static_cast<unsigned int>(position);
    }
    else
        m_leftOver = 0;
}
 
template <class BASE>
void CFB_CipherTemplate<BASE>::UncheckedSetKey(const byte *key, unsigned int length, const NameValuePairs &params)
{
    PolicyInterface &policy = this->AccessPolicy();
    policy.CipherSetKey(params, key, length);
 
    if (this->IsResynchronizable())
    {
        size_t ivLength;
        const byte *iv = this->GetIVAndThrowIfInvalid(params, ivLength);
        policy.CipherResynchronize(iv, ivLength);
    }
 
    m_leftOver = policy.GetBytesPerIteration();
}
 
template <class BASE>
void CFB_CipherTemplate<BASE>::Resynchronize(const byte *iv, int length)
{
    PolicyInterface &policy = this->AccessPolicy();
    policy.CipherResynchronize(iv, this->ThrowIfInvalidIVLength(length));
    m_leftOver = policy.GetBytesPerIteration();
}
 
template <class BASE>
void CFB_CipherTemplate<BASE>::ProcessData(byte *outString, const byte *inString, size_t length)
{
    CRYPTOPP_ASSERT(outString); CRYPTOPP_ASSERT(inString);
    CRYPTOPP_ASSERT(length % this->MandatoryBlockSize() == 0);
 
    PolicyInterface &policy = this->AccessPolicy();
    unsigned int bytesPerIteration = policy.GetBytesPerIteration();
    byte *reg = policy.GetRegisterBegin();
 
    if (m_leftOver)
    {
        const size_t len = STDMIN(m_leftOver, length);
        CombineMessageAndShiftRegister(outString, PtrAdd(reg, bytesPerIteration - m_leftOver), inString, len);
 
        inString = PtrAdd(inString, len);
        outString = PtrAdd(outString, len);
        m_leftOver -= len; length -= len;
    }
 
    if (!length) { return; }
 
    const word32 alignment = policy.GetAlignment();
    const bool inAligned = IsAlignedOn(inString, alignment);
    const bool outAligned = IsAlignedOn(outString, alignment);
    CRYPTOPP_UNUSED(inAligned); CRYPTOPP_UNUSED(outAligned);
 
    if (policy.CanIterate() && length >= bytesPerIteration && outAligned)
    {
        CipherDir cipherDir = GetCipherDir(*this);
        policy.Iterate(outString, inString, cipherDir, length / bytesPerIteration);
 
        const size_t remainder = length % bytesPerIteration;
        inString = PtrAdd(inString, length - remainder);
        outString = PtrAdd(outString, length - remainder);
        length = remainder;
    }
 
    while (length >= bytesPerIteration)
    {
        policy.TransformRegister();
        CombineMessageAndShiftRegister(outString, reg, inString, bytesPerIteration);
 
        inString = PtrAdd(inString, bytesPerIteration);
        outString = PtrAdd(outString, bytesPerIteration);
        length -= 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, size_t length)
{
    xorbuf(reg, message, length);
    std::memcpy(output, reg, length);
}
 
template <class BASE>
void CFB_DecryptionTemplate<BASE>::CombineMessageAndShiftRegister(byte *output, byte *reg, const byte *message, size_t length)
{
    for (size_t i=0; i<length; i++)
    {
        byte b = message[i];
        output[i] = reg[i] ^ b;
        reg[i] = b;
    }
}
 
NAMESPACE_END
 
#endif