filters.cpp

// filters.cpp - originally written and placed in the public domain by Wei Dai

#include "pch.h"
#include "config.h"

#if CRYPTOPP_MSC_VERSION
# pragma warning(disable: 4100 4189 4355)
#endif

#if CRYPTOPP_GCC_DIAGNOSTIC_AVAILABLE
# pragma GCC diagnostic ignored "-Wunused-value"
#endif

#ifndef CRYPTOPP_IMPORTS

#include "filters.h"
#include "mqueue.h"
#include "fltrimpl.h"
#include "argnames.h"
#include "smartptr.h"
#include "stdcpp.h"
#include "misc.h"

NAMESPACE_BEGIN(CryptoPP)

Filter::Filter(BufferedTransformation *attachment)
    : m_attachment(attachment), m_inputPosition(0), m_continueAt(0)
{
}

BufferedTransformation * Filter::NewDefaultAttachment() const
{
    return new MessageQueue;
}

BufferedTransformation * Filter::AttachedTransformation()
{
    if (m_attachment.get() == NULLPTR)
        m_attachment.reset(NewDefaultAttachment());
    return m_attachment.get();
}

const BufferedTransformation *Filter::AttachedTransformation() const
{
    if (m_attachment.get() == NULLPTR)
        const_cast<Filter *>(this)->m_attachment.reset(NewDefaultAttachment());
    return m_attachment.get();
}

void Filter::Detach(BufferedTransformation *newOut)
{
    m_attachment.reset(newOut);
}

void Filter::Insert(Filter *filter)
{
    filter->m_attachment.reset(m_attachment.release());
    m_attachment.reset(filter);
}

size_t Filter::CopyRangeTo2(BufferedTransformation &target, lword &begin, lword end, const std::string &channel, bool blocking) const
{
    return AttachedTransformation()->CopyRangeTo2(target, begin, end, channel, blocking);
}

size_t Filter::TransferTo2(BufferedTransformation &target, lword &transferBytes, const std::string &channel, bool blocking)
{
    return AttachedTransformation()->TransferTo2(target, transferBytes, channel, blocking);
}

void Filter::Initialize(const NameValuePairs &parameters, int propagation)
{
    m_inputPosition = m_continueAt = 0;
    IsolatedInitialize(parameters);
    PropagateInitialize(parameters, propagation);
}

bool Filter::Flush(bool hardFlush, int propagation, bool blocking)
{
    switch (m_continueAt)
    {
    case 0:
        if (IsolatedFlush(hardFlush, blocking))
            return true;
        // fall through
    case 1:
        if (OutputFlush(1, hardFlush, propagation, blocking))
            return true;
        // fall through
    default: ;;
    }
    return false;
}

bool Filter::MessageSeriesEnd(int propagation, bool blocking)
{
    switch (m_continueAt)
    {
    case 0:
        if (IsolatedMessageSeriesEnd(blocking))
            return true;
        // fall through
    case 1:
        if (ShouldPropagateMessageSeriesEnd() && OutputMessageSeriesEnd(1, propagation, blocking))
            return true;
        // fall through
    default: ;;
    }
    return false;
}

void Filter::PropagateInitialize(const NameValuePairs &parameters, int propagation)
{
    if (propagation)
        AttachedTransformation()->Initialize(parameters, propagation-1);
}

size_t Filter::OutputModifiable(int outputSite, byte *inString, size_t length, int messageEnd, bool blocking, const std::string &channel)
{
    if (messageEnd)
        messageEnd--;
    size_t result = AttachedTransformation()->ChannelPutModifiable2(channel, inString, length, messageEnd, blocking);
    m_continueAt = result ? outputSite : 0;
    return result;
}

size_t Filter::Output(int outputSite, const byte *inString, size_t length, int messageEnd, bool blocking, const std::string &channel)
{
    if (messageEnd)
        messageEnd--;
    size_t result = AttachedTransformation()->ChannelPut2(channel, inString, length, messageEnd, blocking);
    m_continueAt = result ? outputSite : 0;
    return result;
}

bool Filter::OutputFlush(int outputSite, bool hardFlush, int propagation, bool blocking, const std::string &channel)
{
    if (propagation && AttachedTransformation()->ChannelFlush(channel, hardFlush, propagation-1, blocking))
    {
        m_continueAt = outputSite;
        return true;
    }
    m_continueAt = 0;
    return false;
}

bool Filter::OutputMessageSeriesEnd(int outputSite, int propagation, bool blocking, const std::string &channel)
{
    if (propagation && AttachedTransformation()->ChannelMessageSeriesEnd(channel, propagation-1, blocking))
    {
        m_continueAt = outputSite;
        return true;
    }
    m_continueAt = 0;
    return false;
}

// *************************************************************

void MeterFilter::ResetMeter()
{
    m_currentMessageBytes = m_totalBytes = m_currentSeriesMessages = m_totalMessages = m_totalMessageSeries = 0;
    m_rangesToSkip.clear();
}

void MeterFilter::AddRangeToSkip(unsigned int message, lword position, lword size, bool sortNow)
{
    MessageRange r = {message, position, size};
    m_rangesToSkip.push_back(r);
    if (sortNow)
        std::sort(m_rangesToSkip.begin(), m_rangesToSkip.end());
}

size_t MeterFilter::PutMaybeModifiable(byte *begin, size_t length, int messageEnd, bool blocking, bool modifiable)
{
    if (!m_transparent)
        return 0;

    size_t t;
    FILTER_BEGIN;

    m_begin = begin;
    m_length = length;

    while (m_length > 0 || messageEnd)
    {
        if (m_length > 0  && !m_rangesToSkip.empty() && m_rangesToSkip.front().message == m_totalMessages && m_currentMessageBytes + m_length > m_rangesToSkip.front().position)
        {
            FILTER_OUTPUT_MAYBE_MODIFIABLE(1, m_begin, t = (size_t)SaturatingSubtract(m_rangesToSkip.front().position, m_currentMessageBytes), false, modifiable);

            CRYPTOPP_ASSERT(t < m_length);
            m_begin = PtrAdd(m_begin, t);
            m_length -= t;
            m_currentMessageBytes += t;
            m_totalBytes += t;

            if (m_currentMessageBytes + m_length < m_rangesToSkip.front().position + m_rangesToSkip.front().size)
                t = m_length;
            else
            {
                t = (size_t)SaturatingSubtract(m_rangesToSkip.front().position + m_rangesToSkip.front().size, m_currentMessageBytes);
                CRYPTOPP_ASSERT(t <= m_length);
                m_rangesToSkip.pop_front();
            }

            m_begin = PtrAdd(m_begin, t);
            m_length -= t;
            m_currentMessageBytes += t;
            m_totalBytes += t;
        }
        else
        {
            FILTER_OUTPUT_MAYBE_MODIFIABLE(2, m_begin, m_length, messageEnd, modifiable);

            m_currentMessageBytes += m_length;
            m_totalBytes += m_length;
            m_length = 0;

            if (messageEnd)
            {
                m_currentMessageBytes = 0;
                m_currentSeriesMessages++;
                m_totalMessages++;
                messageEnd = false;
            }
        }
    }

    FILTER_END_NO_MESSAGE_END;
}

size_t MeterFilter::Put2(const byte *begin, size_t length, int messageEnd, bool blocking)
{
    return PutMaybeModifiable(const_cast<byte *>(begin), length, messageEnd, blocking, false);
}

size_t MeterFilter::PutModifiable2(byte *begin, size_t length, int messageEnd, bool blocking)
{
    return PutMaybeModifiable(begin, length, messageEnd, blocking, true);
}

bool MeterFilter::IsolatedMessageSeriesEnd(bool blocking)
{
    CRYPTOPP_UNUSED(blocking);
    m_currentMessageBytes = 0;
    m_currentSeriesMessages = 0;
    m_totalMessageSeries++;
    return false;
}

// *************************************************************

void FilterWithBufferedInput::BlockQueue::ResetQueue(size_t blockSize, size_t maxBlocks)
{
    m_buffer.New(blockSize * maxBlocks);
    m_blockSize = blockSize;
    m_maxBlocks = maxBlocks;
    m_size = 0;
    m_begin = m_buffer;
}

byte *FilterWithBufferedInput::BlockQueue::GetBlock()
{
    if (m_size >= m_blockSize)
    {
        byte *ptr = m_begin;
        if ((m_begin = PtrAdd(m_begin, m_blockSize)) == m_buffer.end())
            m_begin = m_buffer;
        m_size -= m_blockSize;
        return ptr;
    }
    else
        return NULLPTR;
}

byte *FilterWithBufferedInput::BlockQueue::GetContigousBlocks(size_t &numberOfBytes)
{
    numberOfBytes = STDMIN(numberOfBytes, STDMIN<size_t>(PtrDiff(m_buffer.end(), m_begin), m_size));
    byte *ptr = m_begin;
    m_begin = PtrAdd(m_begin, numberOfBytes);
    m_size -= numberOfBytes;
    if (m_size == 0 || m_begin == m_buffer.end())
        m_begin = m_buffer;
    return ptr;
}

size_t FilterWithBufferedInput::BlockQueue::GetAll(byte *outString)
{
    // Avoid passing NULL pointer to memcpy
    if (!outString) return 0;

    size_t size = m_size;
    size_t numberOfBytes = m_maxBlocks*m_blockSize;
    const byte *ptr = GetContigousBlocks(numberOfBytes);
    memcpy(outString, ptr, numberOfBytes);
    memcpy(PtrAdd(outString, numberOfBytes), m_begin, m_size);
    m_size = 0;
    return size;
}

void FilterWithBufferedInput::BlockQueue::Put(const byte *inString, size_t length)
{
    // Avoid passing NULL pointer to memcpy
    if (!inString || !length) return;

    CRYPTOPP_ASSERT(m_size + length <= m_buffer.size());
    byte *end = (m_size < static_cast<size_t>(PtrDiff(m_buffer.end(), m_begin)) ?
        PtrAdd(m_begin, m_size) : PtrAdd(m_begin, m_size - m_buffer.size()));
    size_t len = STDMIN(length, size_t(m_buffer.end()-end));
    memcpy(end, inString, len);
    if (len < length)
        memcpy(m_buffer, PtrAdd(inString, len), length-len);
    m_size += length;
}

FilterWithBufferedInput::FilterWithBufferedInput(BufferedTransformation *attachment)
    : Filter(attachment), m_firstSize(SIZE_MAX), m_blockSize(0), m_lastSize(SIZE_MAX), m_firstInputDone(false)
{
}

FilterWithBufferedInput::FilterWithBufferedInput(size_t firstSize, size_t blockSize, size_t lastSize, BufferedTransformation *attachment)
    : Filter(attachment), m_firstSize(firstSize), m_blockSize(blockSize), m_lastSize(lastSize), m_firstInputDone(false)
{
    if (m_firstSize == SIZE_MAX || m_blockSize < 1 || m_lastSize == SIZE_MAX)
        throw InvalidArgument("FilterWithBufferedInput: invalid buffer size");

    m_queue.ResetQueue(1, m_firstSize);
}

void FilterWithBufferedInput::IsolatedInitialize(const NameValuePairs &parameters)
{
    InitializeDerivedAndReturnNewSizes(parameters, m_firstSize, m_blockSize, m_lastSize);
    if (m_firstSize == SIZE_MAX || m_blockSize < 1 || m_lastSize == SIZE_MAX)
        throw InvalidArgument("FilterWithBufferedInput: invalid buffer size");
    m_queue.ResetQueue(1, m_firstSize);
    m_firstInputDone = false;
}

bool FilterWithBufferedInput::IsolatedFlush(bool hardFlush, bool blocking)
{
    if (!blocking)
        throw BlockingInputOnly("FilterWithBufferedInput");

    if (hardFlush)
        ForceNextPut();
    FlushDerived();

    return false;
}

size_t FilterWithBufferedInput::PutMaybeModifiable(byte *inString, size_t length, int messageEnd, bool blocking, bool modifiable)
{
    if (!blocking)
        throw BlockingInputOnly("FilterWithBufferedInput");

    if (length != 0)
    {
        size_t newLength = m_queue.CurrentSize() + length;

        if (!m_firstInputDone && newLength >= m_firstSize)
        {
            size_t len = m_firstSize - m_queue.CurrentSize();
            m_queue.Put(inString, len);
            FirstPut(m_queue.GetContigousBlocks(m_firstSize));
            CRYPTOPP_ASSERT(m_queue.CurrentSize() == 0);
            m_queue.ResetQueue(m_blockSize, (2*m_blockSize+m_lastSize-2)/m_blockSize);

            inString = PtrAdd(inString, len);
            newLength -= m_firstSize;
            m_firstInputDone = true;
        }

        if (m_firstInputDone)
        {
            if (m_blockSize == 1)
            {
                while (newLength > m_lastSize && m_queue.CurrentSize() > 0)
                {
                    size_t len = newLength - m_lastSize;
                    byte *ptr = m_queue.GetContigousBlocks(len);
                    NextPutModifiable(ptr, len);
                    newLength -= len;
                }

                if (newLength > m_lastSize)
                {
                    size_t len = newLength - m_lastSize;
                    NextPutMaybeModifiable(inString, len, modifiable);
                    inString = PtrAdd(inString, len);
                    newLength -= len;
                }
            }
            else
            {
                while (newLength >= m_blockSize + m_lastSize && m_queue.CurrentSize() >= m_blockSize)
                {
                    NextPutModifiable(m_queue.GetBlock(), m_blockSize);
                    newLength -= m_blockSize;
                }

                if (newLength >= m_blockSize + m_lastSize && m_queue.CurrentSize() > 0)
                {
                    CRYPTOPP_ASSERT(m_queue.CurrentSize() < m_blockSize);
                    size_t len = m_blockSize - m_queue.CurrentSize();
                    m_queue.Put(inString, len);
                    inString = PtrAdd(inString, len);
                    NextPutModifiable(m_queue.GetBlock(), m_blockSize);
                    newLength -= m_blockSize;
                }

                if (newLength >= m_blockSize + m_lastSize)
                {
                    size_t len = RoundDownToMultipleOf(newLength - m_lastSize, m_blockSize);
                    NextPutMaybeModifiable(inString, len, modifiable);
                    inString = PtrAdd(inString, len);
                    newLength -= len;
                }
            }
        }

        m_queue.Put(inString, newLength - m_queue.CurrentSize());
    }

    if (messageEnd)
    {
        if (!m_firstInputDone && m_firstSize==0)
            FirstPut(NULLPTR);

        SecByteBlock temp(m_queue.CurrentSize());
        m_queue.GetAll(temp);
        LastPut(temp, temp.size());

        m_firstInputDone = false;
        m_queue.ResetQueue(1, m_firstSize);

        // Cast to void to suppress Coverity finding
        (void)Output(1, NULLPTR, 0, messageEnd, blocking);
    }
    return 0;
}

void FilterWithBufferedInput::ForceNextPut()
{
    if (!m_firstInputDone)
        return;

    if (m_blockSize > 1)
    {
        while (m_queue.CurrentSize() >= m_blockSize)
            NextPutModifiable(m_queue.GetBlock(), m_blockSize);
    }
    else
    {
        size_t len;
        while ((len = m_queue.CurrentSize()) > 0)
            NextPutModifiable(m_queue.GetContigousBlocks(len), len);
    }
}

void FilterWithBufferedInput::NextPutMultiple(const byte *inString, size_t length)
{
    CRYPTOPP_ASSERT(m_blockSize > 1);   // m_blockSize = 1 should always override this function
    while (length > 0)
    {
        CRYPTOPP_ASSERT(length >= m_blockSize);
        NextPutSingle(inString);
        inString = PtrAdd(inString, m_blockSize);
        length -= m_blockSize;
    }
}

// *************************************************************

void Redirector::Initialize(const NameValuePairs &parameters, int propagation)
{
    m_target = parameters.GetValueWithDefault("RedirectionTargetPointer", (BufferedTransformation*)NULLPTR);
    m_behavior = parameters.GetIntValueWithDefault("RedirectionBehavior", PASS_EVERYTHING);

    if (m_target && GetPassSignals())
        m_target->Initialize(parameters, propagation);
}

// *************************************************************

ProxyFilter::ProxyFilter(BufferedTransformation *filter, size_t firstSize, size_t lastSize, BufferedTransformation *attachment)
    : FilterWithBufferedInput(firstSize, 1, lastSize, attachment), m_filter(filter)
{
    if (m_filter.get())
        m_filter->Attach(new OutputProxy(*this, false));
}

bool ProxyFilter::IsolatedFlush(bool hardFlush, bool blocking)
{
    return m_filter.get() ? m_filter->Flush(hardFlush, -1, blocking) : false;
}

void ProxyFilter::SetFilter(Filter *filter)
{
    m_filter.reset(filter);
    if (filter)
    {
        OutputProxy *proxy;
        member_ptr<OutputProxy> temp(proxy = new OutputProxy(*this, false));
        m_filter->TransferAllTo(*proxy);
        m_filter->Attach(temp.release());
    }
}

void ProxyFilter::NextPutMultiple(const byte *s, size_t len)
{
    if (m_filter.get())
        m_filter->Put(s, len);
}

void ProxyFilter::NextPutModifiable(byte *s, size_t len)
{
    if (m_filter.get())
        m_filter->PutModifiable(s, len);
}

// *************************************************************

void RandomNumberSink::IsolatedInitialize(const NameValuePairs &parameters)
{
    parameters.GetRequiredParameter("RandomNumberSink", "RandomNumberGeneratorPointer", m_rng);
}

size_t RandomNumberSink::Put2(const byte *begin, size_t length, int messageEnd, bool blocking)
{
    CRYPTOPP_UNUSED(messageEnd); CRYPTOPP_UNUSED(blocking);
    m_rng->IncorporateEntropy(begin, length);
    return 0;
}

size_t ArraySink::Put2(const byte *begin, size_t length, int messageEnd, bool blocking)
{
    CRYPTOPP_UNUSED(messageEnd); CRYPTOPP_UNUSED(blocking);

    // Avoid passing NULL pointer to memcpy. Using memmove due to
    //  Valgrind finding on overlapping buffers.
    size_t copied = 0;
    if (m_buf && begin)
    {
        copied = STDMIN(length, SaturatingSubtract(m_size, m_total));
        memmove(PtrAdd(m_buf, m_total), begin, copied);
    }
    m_total += copied;
    return length - copied;
}

byte * ArraySink::CreatePutSpace(size_t &size)
{
    size = SaturatingSubtract(m_size, m_total);
    return PtrAdd(m_buf, m_total);
}

void ArraySink::IsolatedInitialize(const NameValuePairs &parameters)
{
    ByteArrayParameter array;
    if (!parameters.GetValue(Name::OutputBuffer(), array))
        throw InvalidArgument("ArraySink: missing OutputBuffer argument");
    m_buf = array.begin();
    m_size = array.size();
}

size_t ArrayXorSink::Put2(const byte *begin, size_t length, int messageEnd, bool blocking)
{
    CRYPTOPP_UNUSED(messageEnd); CRYPTOPP_UNUSED(blocking);

    // Avoid passing NULL pointer to xorbuf
    size_t copied = 0;
    if (m_buf && begin)
    {
        copied = STDMIN(length, SaturatingSubtract(m_size, m_total));
        xorbuf(PtrAdd(m_buf, m_total), begin, copied);
    }
    m_total += copied;
    return length - copied;
}

// *************************************************************

StreamTransformationFilter::StreamTransformationFilter(StreamTransformation &c, BufferedTransformation *attachment, BlockPaddingScheme padding)
    : FilterWithBufferedInput(attachment), m_cipher(c), m_padding(DEFAULT_PADDING)
{
    CRYPTOPP_ASSERT(c.MinLastBlockSize() == 0 || c.MinLastBlockSize() > c.MandatoryBlockSize());

    const bool authenticatedFilter = dynamic_cast<AuthenticatedSymmetricCipher *>(&c) != NULLPTR;
    if (authenticatedFilter)
        throw InvalidArgument("StreamTransformationFilter: please use AuthenticatedEncryptionFilter and AuthenticatedDecryptionFilter for AuthenticatedSymmetricCipher");

    // InitializeDerivedAndReturnNewSizes may override some of these
    m_mandatoryBlockSize = m_cipher.MandatoryBlockSize();
    m_optimalBufferSize = m_cipher.OptimalBlockSize();
    m_isSpecial = m_cipher.IsLastBlockSpecial() && m_mandatoryBlockSize > 1;
    m_reservedBufferSize = STDMAX(2*m_mandatoryBlockSize, m_optimalBufferSize);

    IsolatedInitialize(MakeParameters(Name::BlockPaddingScheme(), padding));
}

StreamTransformationFilter::StreamTransformationFilter(StreamTransformation &c, BufferedTransformation *attachment, BlockPaddingScheme padding, bool authenticated)
    : FilterWithBufferedInput(attachment), m_cipher(c), m_padding(DEFAULT_PADDING)
{
    const bool authenticatedFilter = dynamic_cast<AuthenticatedSymmetricCipher *>(&c) != NULLPTR;
    if (!authenticatedFilter)
    {
        CRYPTOPP_ASSERT(c.MinLastBlockSize() == 0 || c.MinLastBlockSize() > c.MandatoryBlockSize());
    }

    if (authenticatedFilter && !authenticated)
        throw InvalidArgument("StreamTransformationFilter: please use AuthenticatedEncryptionFilter and AuthenticatedDecryptionFilter for AuthenticatedSymmetricCipher");

    // InitializeDerivedAndReturnNewSizes may override some of these
    m_mandatoryBlockSize = m_cipher.MandatoryBlockSize();
    m_optimalBufferSize = m_cipher.OptimalBlockSize();
    m_isSpecial = m_cipher.IsLastBlockSpecial() && m_mandatoryBlockSize > 1;
    m_reservedBufferSize = STDMAX(2*m_mandatoryBlockSize, m_optimalBufferSize);

    IsolatedInitialize(MakeParameters(Name::BlockPaddingScheme(), padding));
}

size_t StreamTransformationFilter::LastBlockSize(StreamTransformation &c, BlockPaddingScheme padding)
{
    if (c.MinLastBlockSize() > 0)
        return c.MinLastBlockSize();
    else if (c.MandatoryBlockSize() > 1 && !c.IsForwardTransformation() && padding != NO_PADDING && padding != ZEROS_PADDING)
        return c.MandatoryBlockSize();

    return 0;
}

void StreamTransformationFilter::InitializeDerivedAndReturnNewSizes(const NameValuePairs &parameters, size_t &firstSize, size_t &blockSize, size_t &lastSize)
{
    BlockPaddingScheme padding = parameters.GetValueWithDefault(Name::BlockPaddingScheme(), DEFAULT_PADDING);
    bool isBlockCipher = (m_mandatoryBlockSize > 1 && m_cipher.MinLastBlockSize() == 0);

    if (padding == DEFAULT_PADDING)
        m_padding = isBlockCipher ? PKCS_PADDING : NO_PADDING;
    else
        m_padding = padding;

    if (!isBlockCipher)
    {
        if (m_padding == PKCS_PADDING)
            throw InvalidArgument("StreamTransformationFilter: PKCS_PADDING cannot be used with " + m_cipher.AlgorithmName());
        else if (m_padding == W3C_PADDING)
            throw InvalidArgument("StreamTransformationFilter: W3C_PADDING cannot be used with " + m_cipher.AlgorithmName());
        else if (m_padding == ONE_AND_ZEROS_PADDING)
            throw InvalidArgument("StreamTransformationFilter: ONE_AND_ZEROS_PADDING cannot be used with " + m_cipher.AlgorithmName());
    }

    firstSize = 0;
    blockSize = m_mandatoryBlockSize;
    lastSize = LastBlockSize(m_cipher, m_padding);
}

void StreamTransformationFilter::FirstPut(const byte* inString)
{
    CRYPTOPP_UNUSED(inString);
    m_optimalBufferSize = STDMAX<unsigned int>(m_optimalBufferSize, RoundDownToMultipleOf(4096U, m_optimalBufferSize));
}

void StreamTransformationFilter::NextPutMultiple(const byte *inString, size_t length)
{
    if (!length)
        {return;}

    const size_t s = m_cipher.MandatoryBlockSize();
    do
    {
        size_t len = m_optimalBufferSize;
        byte *space = HelpCreatePutSpace(*AttachedTransformation(), DEFAULT_CHANNEL, s, length, len);
        if (len < length)
        {
            if (len == m_optimalBufferSize)
                len -= m_cipher.GetOptimalBlockSizeUsed();
            len = RoundDownToMultipleOf(len, s);
        }
        else
            len = length;
        m_cipher.ProcessString(space, inString, len);
        AttachedTransformation()->PutModifiable(space, len);
        inString = PtrAdd(inString, len);
        length -= len;
    }
    while (length > 0);
}

void StreamTransformationFilter::NextPutModifiable(byte *inString, size_t length)
{
    m_cipher.ProcessString(inString, length);
    AttachedTransformation()->PutModifiable(inString, length);
}

void StreamTransformationFilter::LastPut(const byte *inString, size_t length)
{
    byte *space = NULLPTR;

#if 1
    // This block is new to StreamTransformationFilter. It somewhat of a hack and was added
    //  for OCB mode; see GitHub Issue 515. The rub with OCB is, its a block cipher and the
    //  last block size can be 0. However, "last block = 0" is not the 0 predacted in the
    //  original code. In the orginal code 0 means "nothing special" so DEFAULT_PADDING is
    //  applied. OCB's 0 literally means a final block size can be 0 or non-0; and no padding
    //  is needed in either case because OCB has its own scheme (see handling of P_* and A_*).
    // Stream ciphers have policy objects to convey how to operate the cipher. The Crypto++
    //  framework operates well when MinLastBlockSize() is 1. However, it did not appear to
    //  cover the OCB case either because we can't stream OCB. It needs full block sizes. In
    //  response we hacked a IsLastBlockSpecial(). When true StreamTransformationFilter
    //  defers to the mode for processing of the last block.
    // The behavior supplied when IsLastBlockSpecial() will likely have to evolve to capture
    //  more complex cases from different authenc modes. I suspect it will have to change
    //  from a simple bool to something that conveys more information, like "last block
    //  no padding" or "custom padding applied by cipher".
    // In some respect we have already hit the need for more information. For example, OCB
    //  calculates the checksum on the cipher text at the same time, so we don't need the
    //  disjoint behavior of calling "EncryptBlock" followed by a separate "AuthenticateBlock".
    //  Additional information may allow us to avoid the two spearate calls.
    if (m_isSpecial)
    {
        const size_t leftOver = length % m_mandatoryBlockSize;
        space = HelpCreatePutSpace(*AttachedTransformation(), DEFAULT_CHANNEL, m_reservedBufferSize);
        length -= leftOver;

        if (length)
        {
            // Process full blocks
            m_cipher.ProcessData(space, inString, length);
            AttachedTransformation()->Put(space, length);
            inString = PtrAdd(inString, length);
        }

        if (leftOver)
        {
            // Process final partial block
            length = m_cipher.ProcessLastBlock(space, m_reservedBufferSize, inString, leftOver);
            AttachedTransformation()->Put(space, length);
        }
        else
        {
            // Process final empty block
            length = m_cipher.ProcessLastBlock(space, m_reservedBufferSize, NULLPTR, 0);
            AttachedTransformation()->Put(space, length);
        }

        return;
    }
#endif

    switch (m_padding)
    {
    case NO_PADDING:
    case ZEROS_PADDING:
        if (length > 0)
        {
            const size_t minLastBlockSize = m_cipher.MinLastBlockSize();
            const bool isForwardTransformation = m_cipher.IsForwardTransformation();

            if (isForwardTransformation && m_padding == ZEROS_PADDING && (minLastBlockSize == 0 || length < minLastBlockSize))
            {
                // do padding
                size_t blockSize = STDMAX(minLastBlockSize, (size_t)m_mandatoryBlockSize);
                space = HelpCreatePutSpace(*AttachedTransformation(), DEFAULT_CHANNEL, blockSize);
                if (inString) {memcpy(space, inString, length);}
                memset(PtrAdd(space, length), 0, blockSize - length);
                size_t used = m_cipher.ProcessLastBlock(space, blockSize, space, blockSize);
                AttachedTransformation()->Put(space, used);
            }
            else
            {
                if (minLastBlockSize == 0)
                {
                    if (isForwardTransformation)
                        throw InvalidDataFormat("StreamTransformationFilter: plaintext length is not a multiple of block size and NO_PADDING is specified");
                    else
                        throw InvalidCiphertext("StreamTransformationFilter: ciphertext length is not a multiple of block size");
                }

                space = HelpCreatePutSpace(*AttachedTransformation(), DEFAULT_CHANNEL, length, m_optimalBufferSize);
                size_t used = m_cipher.ProcessLastBlock(space, length, inString, length);
                AttachedTransformation()->Put(space, used);
            }
        }
        break;

    case PKCS_PADDING:
    case W3C_PADDING:
    case ONE_AND_ZEROS_PADDING:
        unsigned int s;
        s = m_mandatoryBlockSize;
        CRYPTOPP_ASSERT(s > 1);
        space = HelpCreatePutSpace(*AttachedTransformation(), DEFAULT_CHANNEL, s, m_optimalBufferSize);
        if (m_cipher.IsForwardTransformation())
        {
            CRYPTOPP_ASSERT(length < s);
            if (inString) {memcpy(space, inString, length);}
            if (m_padding == PKCS_PADDING)
            {
                CRYPTOPP_ASSERT(s < 256);
                byte pad = static_cast<byte>(s-length);
                memset(PtrAdd(space, length), pad, s-length);
            }
            else if (m_padding == W3C_PADDING)
            {
                CRYPTOPP_ASSERT(s < 256);
                memset(PtrAdd(space, length), 0, s-length-1);
                space[s-1] = static_cast<byte>(s-length);
            }
            else
            {
                space[length] = 0x80;
                memset(PtrAdd(space, length+1), 0, s-length-1);
            }
            m_cipher.ProcessData(space, space, s);
            AttachedTransformation()->Put(space, s);
        }
        else
        {
            if (length != s)
                throw InvalidCiphertext("StreamTransformationFilter: ciphertext length is not a multiple of block size");
            m_cipher.ProcessData(space, inString, s);
            if (m_padding == PKCS_PADDING)
            {
                byte pad = space[s-1];
                                if (pad < 1 || pad > s || FindIfNot(PtrAdd(space, s-pad), PtrAdd(space, s), pad) != PtrAdd(space, s))
                                    throw InvalidCiphertext("StreamTransformationFilter: invalid PKCS #7 block padding found");
                length = s-pad;
            }
            else if (m_padding == W3C_PADDING)
            {
                byte pad = space[s - 1];
                if (pad < 1 || pad > s)
                    throw InvalidCiphertext("StreamTransformationFilter: invalid W3C block padding found");
                length = s - pad;
            }
            else
            {
                while (length > 1 && space[length-1] == 0)
                    --length;
                if (space[--length] != 0x80)
                    throw InvalidCiphertext("StreamTransformationFilter: invalid ones-and-zeros padding found");
            }
            AttachedTransformation()->Put(space, length);
        }
        break;

    default:
        CRYPTOPP_ASSERT(false);
    }
}

// *************************************************************

HashFilter::HashFilter(HashTransformation &hm, BufferedTransformation *attachment, bool putMessage, int truncatedDigestSize, const std::string &messagePutChannel, const std::string &hashPutChannel)
    : m_hashModule(hm), m_putMessage(putMessage), m_digestSize(0), m_space(NULLPTR)
    , m_messagePutChannel(messagePutChannel), m_hashPutChannel(hashPutChannel)
{
    m_digestSize = truncatedDigestSize < 0 ? m_hashModule.DigestSize() : truncatedDigestSize;
    Detach(attachment);
}

void HashFilter::IsolatedInitialize(const NameValuePairs &parameters)
{
    m_putMessage = parameters.GetValueWithDefault(Name::PutMessage(), false);
    int s = parameters.GetIntValueWithDefault(Name::TruncatedDigestSize(), -1);
    m_digestSize = s < 0 ? m_hashModule.DigestSize() : s;
}

size_t HashFilter::Put2(const byte *inString, size_t length, int messageEnd, bool blocking)
{
    FILTER_BEGIN;
    if (m_putMessage)
        FILTER_OUTPUT3(1, 0, inString, length, 0, m_messagePutChannel);
    if (inString && length)
        m_hashModule.Update(inString, length);
    if (messageEnd)
    {
        {
            size_t size;
            m_space = HelpCreatePutSpace(*AttachedTransformation(), m_hashPutChannel, m_digestSize, m_digestSize, size = m_digestSize);
            m_hashModule.TruncatedFinal(m_space, m_digestSize);
        }
        FILTER_OUTPUT3(2, 0, m_space, m_digestSize, messageEnd, m_hashPutChannel);
    }
    FILTER_END_NO_MESSAGE_END;
}

// *************************************************************

HashVerificationFilter::HashVerificationFilter(HashTransformation &hm, BufferedTransformation *attachment, word32 flags, int truncatedDigestSize)
    : FilterWithBufferedInput(attachment)
    , m_hashModule(hm), m_flags(0), m_digestSize(0), m_verified(false)
{
    IsolatedInitialize(MakeParameters(Name::HashVerificationFilterFlags(), flags)(Name::TruncatedDigestSize(), truncatedDigestSize));
}

void HashVerificationFilter::InitializeDerivedAndReturnNewSizes(const NameValuePairs &parameters, size_t &firstSize, size_t &blockSize, size_t &lastSize)
{
    m_flags = parameters.GetValueWithDefault(Name::HashVerificationFilterFlags(), (word32)DEFAULT_FLAGS);
    int s = parameters.GetIntValueWithDefault(Name::TruncatedDigestSize(), -1);
    m_digestSize = s < 0 ? m_hashModule.DigestSize() : s;
    m_verified = false;
    firstSize = m_flags & HASH_AT_BEGIN ? m_digestSize : 0;
    blockSize = 1;
    lastSize = m_flags & HASH_AT_BEGIN ? 0 : m_digestSize;
}

void HashVerificationFilter::FirstPut(const byte *inString)
{
    if (m_flags & HASH_AT_BEGIN)
    {
        m_expectedHash.New(m_digestSize);
        if (inString) {memcpy(m_expectedHash, inString, m_expectedHash.size());}
        if (m_flags & PUT_HASH)
            AttachedTransformation()->Put(inString, m_expectedHash.size());
    }
}

void HashVerificationFilter::NextPutMultiple(const byte *inString, size_t length)
{
    m_hashModule.Update(inString, length);
    if (m_flags & PUT_MESSAGE)
        AttachedTransformation()->Put(inString, length);
}

void HashVerificationFilter::LastPut(const byte *inString, size_t length)
{
    if (m_flags & HASH_AT_BEGIN)
    {
        CRYPTOPP_ASSERT(length == 0);
        m_verified = m_hashModule.TruncatedVerify(m_expectedHash, m_digestSize);
    }
    else
    {
        m_verified = (length==m_digestSize && m_hashModule.TruncatedVerify(inString, length));
        if (m_flags & PUT_HASH)
            AttachedTransformation()->Put(inString, length);
    }

    if (m_flags & PUT_RESULT)
        AttachedTransformation()->Put(m_verified);

    if ((m_flags & THROW_EXCEPTION) && !m_verified)
        throw HashVerificationFailed();
}

// *************************************************************

AuthenticatedEncryptionFilter::AuthenticatedEncryptionFilter(AuthenticatedSymmetricCipher &c, BufferedTransformation *attachment,
                                bool putAAD, int truncatedDigestSize, const std::string &macChannel, BlockPaddingScheme padding)
    : StreamTransformationFilter(c, attachment, padding, true)
    , m_hf(c, new OutputProxy(*this, false), putAAD, truncatedDigestSize, AAD_CHANNEL, macChannel)
{
    CRYPTOPP_ASSERT(c.IsForwardTransformation());
}

void AuthenticatedEncryptionFilter::IsolatedInitialize(const NameValuePairs &parameters)
{
    m_hf.IsolatedInitialize(parameters);
    StreamTransformationFilter::IsolatedInitialize(parameters);
}

byte * AuthenticatedEncryptionFilter::ChannelCreatePutSpace(const std::string &channel, size_t &size)
{
    if (channel.empty())
        return StreamTransformationFilter::CreatePutSpace(size);

    if (channel == AAD_CHANNEL)
        return m_hf.CreatePutSpace(size);

    throw InvalidChannelName("AuthenticatedEncryptionFilter", channel);
}

size_t AuthenticatedEncryptionFilter::ChannelPut2(const std::string &channel, const byte *begin, size_t length, int messageEnd, bool blocking)
{
    if (channel.empty())
        return StreamTransformationFilter::Put2(begin, length, messageEnd, blocking);

    if (channel == AAD_CHANNEL)
        return m_hf.Put2(begin, length, 0, blocking);

    throw InvalidChannelName("AuthenticatedEncryptionFilter", channel);
}

void AuthenticatedEncryptionFilter::LastPut(const byte *inString, size_t length)
{
    StreamTransformationFilter::LastPut(inString, length);
    m_hf.MessageEnd();
}

// *************************************************************

AuthenticatedDecryptionFilter::AuthenticatedDecryptionFilter(AuthenticatedSymmetricCipher &c, BufferedTransformation *attachment, word32 flags, int truncatedDigestSize, BlockPaddingScheme padding)
    : FilterWithBufferedInput(attachment)
    , m_hashVerifier(c, new OutputProxy(*this, false))
    , m_streamFilter(c, new OutputProxy(*this, false), padding, true)
{
    CRYPTOPP_ASSERT(!c.IsForwardTransformation() || c.IsSelfInverting());
    IsolatedInitialize(MakeParameters(Name::BlockPaddingScheme(), padding)(Name::AuthenticatedDecryptionFilterFlags(), flags)(Name::TruncatedDigestSize(), truncatedDigestSize));
}

void AuthenticatedDecryptionFilter::InitializeDerivedAndReturnNewSizes(const NameValuePairs &parameters, size_t &firstSize, size_t &blockSize, size_t &lastSize)
{
    word32 flags = parameters.GetValueWithDefault(Name::AuthenticatedDecryptionFilterFlags(), (word32)DEFAULT_FLAGS);

    m_hashVerifier.Initialize(CombinedNameValuePairs(parameters, MakeParameters(Name::HashVerificationFilterFlags(), flags)));
    m_streamFilter.Initialize(parameters);

    firstSize = m_hashVerifier.m_firstSize;
    blockSize = 1;
    lastSize = m_hashVerifier.m_lastSize;
}

byte * AuthenticatedDecryptionFilter::ChannelCreatePutSpace(const std::string &channel, size_t &size)
{
    if (channel.empty())
        return m_streamFilter.CreatePutSpace(size);

    if (channel == AAD_CHANNEL)
        return m_hashVerifier.CreatePutSpace(size);

    throw InvalidChannelName("AuthenticatedDecryptionFilter", channel);
}

size_t AuthenticatedDecryptionFilter::ChannelPut2(const std::string &channel, const byte *begin, size_t length, int messageEnd, bool blocking)
{
    if (channel.empty())
    {
        if (m_lastSize > 0)
            m_hashVerifier.ForceNextPut();
        return FilterWithBufferedInput::Put2(begin, length, messageEnd, blocking);
    }

    if (channel == AAD_CHANNEL)
        return m_hashVerifier.Put2(begin, length, 0, blocking);

    throw InvalidChannelName("AuthenticatedDecryptionFilter", channel);
}

void AuthenticatedDecryptionFilter::FirstPut(const byte *inString)
{
    m_hashVerifier.Put(inString, m_firstSize);
}

void AuthenticatedDecryptionFilter::NextPutMultiple(const byte *inString, size_t length)
{
    m_streamFilter.Put(inString, length);
}

void AuthenticatedDecryptionFilter::LastPut(const byte *inString, size_t length)
{
    m_streamFilter.MessageEnd();
    m_hashVerifier.PutMessageEnd(inString, length);
}

// *************************************************************

void SignerFilter::IsolatedInitialize(const NameValuePairs &parameters)
{
    m_putMessage = parameters.GetValueWithDefault(Name::PutMessage(), false);
    m_messageAccumulator.reset(m_signer.NewSignatureAccumulator(m_rng));
}

size_t SignerFilter::Put2(const byte *inString, size_t length, int messageEnd, bool blocking)
{
    FILTER_BEGIN;
    m_messageAccumulator->Update(inString, length);
    if (m_putMessage)
        FILTER_OUTPUT(1, inString, length, 0);
    if (messageEnd)
    {
        m_buf.New(m_signer.SignatureLength());
        m_signer.Sign(m_rng, m_messageAccumulator.release(), m_buf);
        FILTER_OUTPUT(2, m_buf, m_buf.size(), messageEnd);
        m_messageAccumulator.reset(m_signer.NewSignatureAccumulator(m_rng));
    }
    FILTER_END_NO_MESSAGE_END;
}

SignatureVerificationFilter::SignatureVerificationFilter(const PK_Verifier &verifier, BufferedTransformation *attachment, word32 flags)
    : FilterWithBufferedInput(attachment)
    , m_verifier(verifier), m_flags(0), m_verified(0)
{
    IsolatedInitialize(MakeParameters(Name::SignatureVerificationFilterFlags(), flags));
}

void SignatureVerificationFilter::InitializeDerivedAndReturnNewSizes(const NameValuePairs &parameters, size_t &firstSize, size_t &blockSize, size_t &lastSize)
{
    m_flags = parameters.GetValueWithDefault(Name::SignatureVerificationFilterFlags(), (word32)DEFAULT_FLAGS);
    m_messageAccumulator.reset(m_verifier.NewVerificationAccumulator());
    size_t size = m_verifier.SignatureLength();
    CRYPTOPP_ASSERT(size != 0); // TODO: handle recoverable signature scheme
    m_verified = false;
    firstSize = m_flags & SIGNATURE_AT_BEGIN ? size : 0;
    blockSize = 1;
    lastSize = m_flags & SIGNATURE_AT_BEGIN ? 0 : size;
}

void SignatureVerificationFilter::FirstPut(const byte *inString)
{
    if (m_flags & SIGNATURE_AT_BEGIN)
    {
        if (m_verifier.SignatureUpfront())
            m_verifier.InputSignature(*m_messageAccumulator, inString, m_verifier.SignatureLength());
        else
        {
            m_signature.New(m_verifier.SignatureLength());
            if (inString) {memcpy(m_signature, inString, m_signature.size());}
        }

        if (m_flags & PUT_SIGNATURE)
            AttachedTransformation()->Put(inString, m_signature.size());
    }
    else
    {
        CRYPTOPP_ASSERT(!m_verifier.SignatureUpfront());
    }
}

void SignatureVerificationFilter::NextPutMultiple(const byte *inString, size_t length)
{
    m_messageAccumulator->Update(inString, length);
    if (m_flags & PUT_MESSAGE)
        AttachedTransformation()->Put(inString, length);
}

void SignatureVerificationFilter::LastPut(const byte *inString, size_t length)
{
    if (m_flags & SIGNATURE_AT_BEGIN)
    {
        CRYPTOPP_ASSERT(length == 0);
        m_verifier.InputSignature(*m_messageAccumulator, m_signature, m_signature.size());
        m_verified = m_verifier.VerifyAndRestart(*m_messageAccumulator);
    }
    else
    {
        m_verifier.InputSignature(*m_messageAccumulator, inString, length);
        m_verified = m_verifier.VerifyAndRestart(*m_messageAccumulator);
        if (m_flags & PUT_SIGNATURE)
            AttachedTransformation()->Put(inString, length);
    }

    if (m_flags & PUT_RESULT)
        AttachedTransformation()->Put(m_verified);

    if ((m_flags & THROW_EXCEPTION) && !m_verified)
        throw SignatureVerificationFailed();
}

// *************************************************************

size_t Source::PumpAll2(bool blocking)
{
    unsigned int messageCount = UINT_MAX;
    do {
        RETURN_IF_NONZERO(PumpMessages2(messageCount, blocking));
    } while(messageCount == UINT_MAX);

    return 0;
}

bool Store::GetNextMessage()
{
    if (!m_messageEnd && !AnyRetrievable())
    {
        m_messageEnd=true;
        return true;
    }
    else
        return false;
}

unsigned int Store::CopyMessagesTo(BufferedTransformation &target, unsigned int count, const std::string &channel) const
{
    if (m_messageEnd || count == 0)
        return 0;
    else
    {
        CopyTo(target, ULONG_MAX, channel);
        if (GetAutoSignalPropagation())
            target.ChannelMessageEnd(channel, GetAutoSignalPropagation()-1);
        return 1;
    }
}

void StringStore::StoreInitialize(const NameValuePairs &parameters)
{
    ConstByteArrayParameter array;
    if (!parameters.GetValue(Name::InputBuffer(), array))
        throw InvalidArgument("StringStore: missing InputBuffer argument");
    m_store = array.begin();
    m_length = array.size();
    m_count = 0;
}

size_t StringStore::TransferTo2(BufferedTransformation &target, lword &transferBytes, const std::string &channel, bool blocking)
{
    lword position = 0;
    size_t blockedBytes = CopyRangeTo2(target, position, transferBytes, channel, blocking);
    m_count += static_cast<size_t>(position);
    transferBytes = position;
    return blockedBytes;
}

size_t StringStore::CopyRangeTo2(BufferedTransformation &target, lword &begin, lword end, const std::string &channel, bool blocking) const
{
    size_t i = UnsignedMin(m_length, m_count+begin);
    size_t len = UnsignedMin(m_length-i, end-begin);
    size_t blockedBytes = target.ChannelPut2(channel, PtrAdd(m_store, i), len, 0, blocking);
    if (!blockedBytes)
        begin = PtrAdd(begin, len);
    return blockedBytes;
}

void RandomNumberStore::StoreInitialize(const NameValuePairs &parameters)
{
    parameters.GetRequiredParameter("RandomNumberStore", "RandomNumberGeneratorPointer", m_rng);
    int length;
    parameters.GetRequiredIntParameter("RandomNumberStore", "RandomNumberStoreSize", length);
    m_length = length;
}

size_t RandomNumberStore::TransferTo2(BufferedTransformation &target, lword &transferBytes, const std::string &channel, bool blocking)
{
    if (!blocking)
        throw NotImplemented("RandomNumberStore: nonblocking transfer is not implemented by this object");

    transferBytes = UnsignedMin(transferBytes, m_length - m_count);
    m_rng->GenerateIntoBufferedTransformation(target, channel, transferBytes);
    m_count += transferBytes;

    return 0;
}

size_t NullStore::CopyRangeTo2(BufferedTransformation &target, lword &begin, lword end, const std::string &channel, bool blocking) const
{
    static const byte nullBytes[128] = {0};
    while (begin < end)
    {
        size_t len = (size_t)STDMIN(end-begin, lword(128));
        size_t blockedBytes = target.ChannelPut2(channel, nullBytes, len, 0, blocking);
        if (blockedBytes)
            return blockedBytes;
        begin = PtrAdd(begin, len);
    }
    return 0;
}

size_t NullStore::TransferTo2(BufferedTransformation &target, lword &transferBytes, const std::string &channel, bool blocking)
{
    lword begin = 0;
    size_t blockedBytes = NullStore::CopyRangeTo2(target, begin, transferBytes, channel, blocking);
    transferBytes = begin; m_size -= begin;
    return blockedBytes;
}

NAMESPACE_END

#endif