ida.cpp

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

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

#include "ida.h"
#include "stdcpp.h"
#include "algebra.h"
#include "polynomi.h"
#include "polynomi.cpp"

NAMESPACE_BEGIN(CryptoPP)

#if (defined(_MSC_VER) && (_MSC_VER < 1400)) && !defined(__MWERKS__)
    // VC60 and VC7 workaround: built-in reverse_iterator has two template parameters, Dinkumware only has one
    typedef std::reverse_bidirectional_iterator<const byte *, const byte> RevIt;
#elif defined(_RWSTD_NO_CLASS_PARTIAL_SPEC)
    typedef std::reverse_iterator<const byte *, std::random_access_iterator_tag, const byte> RevIt;
#else
    typedef std::reverse_iterator<const byte *> RevIt;
#endif

void RawIDA::IsolatedInitialize(const NameValuePairs &parameters)
{
    if (!parameters.GetIntValue("RecoveryThreshold", m_threshold))
        throw InvalidArgument("RawIDA: missing RecoveryThreshold argument");

    CRYPTOPP_ASSERT(m_threshold > 0);
    if (m_threshold <= 0)
        throw InvalidArgument("RawIDA: RecoveryThreshold must be greater than 0");

    m_lastMapPosition = m_inputChannelMap.end();
    m_channelsReady = 0;
    m_channelsFinished = 0;
    m_w.New(m_threshold);
    m_y.New(m_threshold);
    m_inputQueues.reserve(m_threshold);

    m_outputChannelIds.clear();
    m_outputChannelIdStrings.clear();
    m_outputQueues.clear();

    word32 outputChannelID;
    if (parameters.GetValue("OutputChannelID", outputChannelID))
        AddOutputChannel(outputChannelID);
    else
    {
        int nShares = parameters.GetIntValueWithDefault("NumberOfShares", m_threshold);
        CRYPTOPP_ASSERT(nShares > 0);
        if (nShares <= 0) {nShares = m_threshold;}
        for (unsigned int i=0; i< (unsigned int)(nShares); i++)
            AddOutputChannel(i);
    }
}

unsigned int RawIDA::InsertInputChannel(word32 channelId)
{
    if (m_lastMapPosition != m_inputChannelMap.end())
    {
        if (m_lastMapPosition->first == channelId)
            goto skipFind;
        ++m_lastMapPosition;
        if (m_lastMapPosition != m_inputChannelMap.end() && m_lastMapPosition->first == channelId)
            goto skipFind;
    }
    m_lastMapPosition = m_inputChannelMap.find(channelId);

skipFind:
    if (m_lastMapPosition == m_inputChannelMap.end())
    {
        if (m_inputChannelIds.size() == size_t(m_threshold))
            return m_threshold;

        m_lastMapPosition = m_inputChannelMap.insert(InputChannelMap::value_type(channelId, (unsigned int)m_inputChannelIds.size())).first;
        m_inputQueues.push_back(MessageQueue());
        m_inputChannelIds.push_back(channelId);

        if (m_inputChannelIds.size() == size_t(m_threshold))
            PrepareInterpolation();
    }
    return m_lastMapPosition->second;
}

unsigned int RawIDA::LookupInputChannel(word32 channelId) const
{
    std::map<word32, unsigned int>::const_iterator it = m_inputChannelMap.find(channelId);
    if (it == m_inputChannelMap.end())
        return m_threshold;
    else
        return it->second;
}

void RawIDA::ChannelData(word32 channelId, const byte *inString, size_t length, bool messageEnd)
{
    int i = InsertInputChannel(channelId);
    if (i < m_threshold)
    {
        lword size = m_inputQueues[i].MaxRetrievable();
        m_inputQueues[i].Put(inString, length);
        if (size < 4 && size + length >= 4)
        {
            m_channelsReady++;
            if (m_channelsReady == size_t(m_threshold))
                ProcessInputQueues();
        }

        if (messageEnd)
        {
            m_inputQueues[i].MessageEnd();
            if (m_inputQueues[i].NumberOfMessages() == 1)
            {
                m_channelsFinished++;
                if (m_channelsFinished == size_t(m_threshold))
                {
                    m_channelsReady = 0;
                    for (i=0; i<m_threshold; i++)
                        m_channelsReady += m_inputQueues[i].AnyRetrievable();
                    ProcessInputQueues();
                }
            }
        }
    }
}

lword RawIDA::InputBuffered(word32 channelId) const
{
    int i = LookupInputChannel(channelId);
    return i < m_threshold ? m_inputQueues[i].MaxRetrievable() : 0;
}

void RawIDA::ComputeV(unsigned int i)
{
    if (i >= m_v.size())
    {
        m_v.resize(i+1);
        m_outputToInput.resize(i+1);
    }

    m_outputToInput[i] = LookupInputChannel(m_outputChannelIds[i]);
    if (m_outputToInput[i] == size_t(m_threshold) && i * size_t(m_threshold) <= 1000*1000)
    {
        m_v[i].resize(m_threshold);
        PrepareBulkPolynomialInterpolationAt(m_gf32, m_v[i].begin(), m_outputChannelIds[i], &(m_inputChannelIds[0]), m_w.begin(), m_threshold);
    }
}

void RawIDA::AddOutputChannel(word32 channelId)
{
    m_outputChannelIds.push_back(channelId);
    m_outputChannelIdStrings.push_back(WordToString(channelId));
    m_outputQueues.push_back(ByteQueue());
    if (m_inputChannelIds.size() == size_t(m_threshold))
        ComputeV((unsigned int)m_outputChannelIds.size() - 1);
}

void RawIDA::PrepareInterpolation()
{
    CRYPTOPP_ASSERT(m_inputChannelIds.size() == size_t(m_threshold));
    PrepareBulkPolynomialInterpolation(m_gf32, m_w.begin(), &(m_inputChannelIds[0]), (unsigned int)(m_threshold));
    for (unsigned int i=0; i<m_outputChannelIds.size(); i++)
        ComputeV(i);
}

void RawIDA::ProcessInputQueues()
{
    bool finished = (m_channelsFinished == size_t(m_threshold));
    unsigned int i;

    while (finished ? m_channelsReady > 0 : m_channelsReady == size_t(m_threshold))
    {
        m_channelsReady = 0;
        for (i=0; i<size_t(m_threshold); i++)
        {
            MessageQueue &queue = m_inputQueues[i];
            queue.GetWord32(m_y[i]);

            if (finished)
                m_channelsReady += queue.AnyRetrievable();
            else
                m_channelsReady += queue.NumberOfMessages() > 0 || queue.MaxRetrievable() >= 4;
        }

        for (i=0; (unsigned int)i<m_outputChannelIds.size(); i++)
        {
            if (m_outputToInput[i] != size_t(m_threshold))
                m_outputQueues[i].PutWord32(m_y[m_outputToInput[i]]);
            else if (m_v[i].size() == size_t(m_threshold))
                m_outputQueues[i].PutWord32(BulkPolynomialInterpolateAt(m_gf32, m_y.begin(), m_v[i].begin(), m_threshold));
            else
            {
                m_u.resize(m_threshold);
                PrepareBulkPolynomialInterpolationAt(m_gf32, m_u.begin(), m_outputChannelIds[i], &(m_inputChannelIds[0]), m_w.begin(), m_threshold);
                m_outputQueues[i].PutWord32(BulkPolynomialInterpolateAt(m_gf32, m_y.begin(), m_u.begin(), m_threshold));
            }
        }
    }

    if (m_outputChannelIds.size() > 0 && m_outputQueues[0].AnyRetrievable())
        FlushOutputQueues();

    if (finished)
    {
        OutputMessageEnds();

        m_channelsReady = 0;
        m_channelsFinished = 0;
        m_v.clear();

        std::vector<MessageQueue> inputQueues;
        std::vector<word32> inputChannelIds;

        inputQueues.swap(m_inputQueues);
        inputChannelIds.swap(m_inputChannelIds);
        m_inputChannelMap.clear();
        m_lastMapPosition = m_inputChannelMap.end();

        for (i=0; i<size_t(m_threshold); i++)
        {
            inputQueues[i].GetNextMessage();
            inputQueues[i].TransferAllTo(*AttachedTransformation(), WordToString(inputChannelIds[i]));
        }
    }
}

void RawIDA::FlushOutputQueues()
{
    for (unsigned int i=0; i<m_outputChannelIds.size(); i++)
        m_outputQueues[i].TransferAllTo(*AttachedTransformation(), m_outputChannelIdStrings[i]);
}

void RawIDA::OutputMessageEnds()
{
    if (GetAutoSignalPropagation() != 0)
    {
        for (unsigned int i=0; i<m_outputChannelIds.size(); i++)
            AttachedTransformation()->ChannelMessageEnd(m_outputChannelIdStrings[i], GetAutoSignalPropagation()-1);
    }
}

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

void SecretSharing::IsolatedInitialize(const NameValuePairs &parameters)
{
    m_pad = parameters.GetValueWithDefault("AddPadding", true);
    m_ida.IsolatedInitialize(parameters);
}

size_t SecretSharing::Put2(const byte *begin, size_t length, int messageEnd, bool blocking)
{
    if (!blocking)
        throw BlockingInputOnly("SecretSharing");

    SecByteBlock buf(UnsignedMin(256, length));
    unsigned int threshold = m_ida.GetThreshold();
    while (length > 0)
    {
        size_t len = STDMIN(length, buf.size());
        m_ida.ChannelData(0xffffffff, begin, len, false);
        for (unsigned int i=0; i<threshold-1; i++)
        {
            m_rng.GenerateBlock(buf, len);
            m_ida.ChannelData(i, buf, len, false);
        }
        length -= len;
        begin += len;
    }

    if (messageEnd)
    {
        m_ida.SetAutoSignalPropagation(messageEnd-1);
        if (m_pad)
        {
            SecretSharing::Put(1);
            while (m_ida.InputBuffered(0xffffffff) > 0)
                SecretSharing::Put(0);
        }
        m_ida.ChannelData(0xffffffff, NULLPTR, 0, true);
        for (unsigned int i=0; i<m_ida.GetThreshold()-1; i++)
            m_ida.ChannelData(i, NULLPTR, 0, true);
    }

    return 0;
}

void SecretRecovery::IsolatedInitialize(const NameValuePairs &parameters)
{
    m_pad = parameters.GetValueWithDefault("RemovePadding", true);
    RawIDA::IsolatedInitialize(CombinedNameValuePairs(parameters, MakeParameters("OutputChannelID", (word32)0xffffffff)));
}

void SecretRecovery::FlushOutputQueues()
{
    if (m_pad)
        m_outputQueues[0].TransferTo(*AttachedTransformation(), m_outputQueues[0].MaxRetrievable()-4);
    else
        m_outputQueues[0].TransferTo(*AttachedTransformation());
}

void SecretRecovery::OutputMessageEnds()
{
    if (m_pad)
    {
        PaddingRemover paddingRemover(new Redirector(*AttachedTransformation()));
        m_outputQueues[0].TransferAllTo(paddingRemover);
    }

    if (GetAutoSignalPropagation() != 0)
        AttachedTransformation()->MessageEnd(GetAutoSignalPropagation()-1);
}

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

void InformationDispersal::IsolatedInitialize(const NameValuePairs &parameters)
{
    m_nextChannel = 0;
    m_pad = parameters.GetValueWithDefault("AddPadding", true);
    m_ida.IsolatedInitialize(parameters);
}

size_t InformationDispersal::Put2(const byte *begin, size_t length, int messageEnd, bool blocking)
{
    if (!blocking)
        throw BlockingInputOnly("InformationDispersal");

    while (length--)
    {
        m_ida.ChannelData(m_nextChannel, begin, 1, false);
        begin++;
        m_nextChannel++;
        if (m_nextChannel == m_ida.GetThreshold())
            m_nextChannel = 0;
    }

    if (messageEnd)
    {
        m_ida.SetAutoSignalPropagation(messageEnd-1);
        if (m_pad)
            InformationDispersal::Put(1);
        for (word32 i=0; i<m_ida.GetThreshold(); i++)
            m_ida.ChannelData(i, NULLPTR, 0, true);
    }

    return 0;
}

void InformationRecovery::IsolatedInitialize(const NameValuePairs &parameters)
{
    m_pad = parameters.GetValueWithDefault("RemovePadding", true);
    RawIDA::IsolatedInitialize(parameters);
}

void InformationRecovery::FlushOutputQueues()
{
    while (m_outputQueues[0].AnyRetrievable())
    {
        for (unsigned int i=0; i<m_outputChannelIds.size(); i++)
            m_outputQueues[i].TransferTo(m_queue, 1);
    }

    if (m_pad)
        m_queue.TransferTo(*AttachedTransformation(), m_queue.MaxRetrievable()-4*m_threshold);
    else
        m_queue.TransferTo(*AttachedTransformation());
}

void InformationRecovery::OutputMessageEnds()
{
    if (m_pad)
    {
        PaddingRemover paddingRemover(new Redirector(*AttachedTransformation()));
        m_queue.TransferAllTo(paddingRemover);
    }

    if (GetAutoSignalPropagation() != 0)
        AttachedTransformation()->MessageEnd(GetAutoSignalPropagation()-1);
}

size_t PaddingRemover::Put2(const byte *begin, size_t length, int messageEnd, bool blocking)
{
    if (!blocking)
        throw BlockingInputOnly("PaddingRemover");

    const byte *const end = begin + length;

    if (m_possiblePadding)
    {
        size_t len = FindIfNot(begin, end, byte(0)) - begin;
        m_zeroCount += len;
        begin += len;
        if (begin == end)
            return 0;

        AttachedTransformation()->Put(1);
        while (m_zeroCount--)
            AttachedTransformation()->Put(0);
        AttachedTransformation()->Put(*begin++);
        m_possiblePadding = false;
    }

    const byte *x = FindIfNot(RevIt(end), RevIt(begin), byte(0)).base();
    if (x != begin && *(x-1) == 1)
    {
        AttachedTransformation()->Put(begin, x-begin-1);
        m_possiblePadding = true;
        m_zeroCount = end - x;
    }
    else
        AttachedTransformation()->Put(begin, end-begin);

    if (messageEnd)
    {
        m_possiblePadding = false;
        Output(0, begin, length, messageEnd, blocking);
    }
    return 0;
}

NAMESPACE_END