ida.h

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

/// \file ida.h
/// \brief Classes for Rabin's Information Dispersal and Shamir's Secret Sharing algorithms

#ifndef CRYPTOPP_IDA_H
#define CRYPTOPP_IDA_H

#include "cryptlib.h"
#include "mqueue.h"
#include "filters.h"
#include "channels.h"
#include "secblock.h"
#include "gf2_32.h"
#include "stdcpp.h"
#include "misc.h"

NAMESPACE_BEGIN(CryptoPP)

/// \brief Secret sharing and information dispersal base class
/// \since Crypto++ 1.0
class RawIDA : public AutoSignaling<Unflushable<Multichannel<Filter> > >
{
public:
    RawIDA(BufferedTransformation *attachment=NULLPTR)
        : m_channelsReady(0), m_channelsFinished(0), m_threshold (0)
            {Detach(attachment);}

    unsigned int GetThreshold() const {return m_threshold;}
    void AddOutputChannel(word32 channelId);
    void ChannelData(word32 channelId, const byte *inString, size_t length, bool messageEnd);
    lword InputBuffered(word32 channelId) const;

    void IsolatedInitialize(const NameValuePairs &parameters=g_nullNameValuePairs);
    size_t ChannelPut2(const std::string &channel, const byte *begin, size_t length, int messageEnd, bool blocking)
    {
        if (!blocking)
            throw BlockingInputOnly("RawIDA");
        ChannelData(StringToWord<word32>(channel), begin, length, messageEnd != 0);
        return 0;
    }

protected:
    virtual void FlushOutputQueues();
    virtual void OutputMessageEnds();

    unsigned int InsertInputChannel(word32 channelId);
    unsigned int LookupInputChannel(word32 channelId) const;
    void ComputeV(unsigned int);
    void PrepareInterpolation();
    void ProcessInputQueues();

    typedef std::map<word32, unsigned int> InputChannelMap;
    InputChannelMap m_inputChannelMap;
    InputChannelMap::iterator m_lastMapPosition;
    std::vector<MessageQueue> m_inputQueues;
    std::vector<word32> m_inputChannelIds, m_outputChannelIds, m_outputToInput;
    std::vector<std::string> m_outputChannelIdStrings;
    std::vector<ByteQueue> m_outputQueues;
    std::vector<SecBlock<word32> > m_v;
    SecBlock<word32> m_u, m_w, m_y;
    const GF2_32 m_gf32;
    unsigned int m_channelsReady, m_channelsFinished;
    int m_threshold;
};

/// \brief Shamir's Secret Sharing Algorithm
/// \details SecretSharing is a variant of Shamir's secret sharing algorithm
/// \sa SecretRecovery, SecretRecovery, InformationDispersal, InformationRecovery
/// \since Crypto++ 1.0
class SecretSharing : public CustomFlushPropagation<Filter>
{
public:
    /// \brief Construct a SecretSharing
    SecretSharing(RandomNumberGenerator &rng, int threshold, int nShares, BufferedTransformation *attachment=NULLPTR, bool addPadding=true)
        : m_rng(rng), m_ida(new OutputProxy(*this, true))
    {
        Detach(attachment);
        IsolatedInitialize(MakeParameters("RecoveryThreshold", threshold)("NumberOfShares", nShares)("AddPadding", addPadding));
    }

    void IsolatedInitialize(const NameValuePairs &parameters=g_nullNameValuePairs);
    size_t Put2(const byte *begin, size_t length, int messageEnd, bool blocking);
    bool Flush(bool hardFlush, int propagation=-1, bool blocking=true) {return m_ida.Flush(hardFlush, propagation, blocking);}

protected:
    RandomNumberGenerator &m_rng;
    RawIDA m_ida;
    bool m_pad;
};

/// \brief Shamir's Secret Sharing Algorithm
/// \details SecretSharing is a variant of Shamir's secret sharing algorithm
/// \sa SecretRecovery, SecretRecovery, InformationDispersal, InformationRecovery
/// \since Crypto++ 1.0
class SecretRecovery : public RawIDA
{
public:
    /// \brief Construct a SecretRecovery
    SecretRecovery(int threshold, BufferedTransformation *attachment=NULLPTR, bool removePadding=true)
        : RawIDA(attachment)
        {IsolatedInitialize(MakeParameters("RecoveryThreshold", threshold)("RemovePadding", removePadding));}

    void IsolatedInitialize(const NameValuePairs &parameters=g_nullNameValuePairs);

protected:
    void FlushOutputQueues();
    void OutputMessageEnds();

    bool m_pad;
};

/// a variant of Rabin's Information Dispersal Algorithm

/// \brief Rabin's Information Dispersal Algorithm
/// \details InformationDispersal is a variant of Rabin's information dispersal algorithm
/// \sa SecretRecovery, SecretRecovery, InformationDispersal, InformationRecovery
/// \since Crypto++ 1.0
class InformationDispersal : public CustomFlushPropagation<Filter>
{
public:
    /// \brief Construct a InformationDispersal
    InformationDispersal(int threshold, int nShares, BufferedTransformation *attachment=NULLPTR, bool addPadding=true)
        : m_ida(new OutputProxy(*this, true)), m_pad(false), m_nextChannel(0)
    {
        Detach(attachment);
        IsolatedInitialize(MakeParameters("RecoveryThreshold", threshold)("NumberOfShares", nShares)("AddPadding", addPadding));
    }

    void IsolatedInitialize(const NameValuePairs &parameters=g_nullNameValuePairs);
    size_t Put2(const byte *begin, size_t length, int messageEnd, bool blocking);
    bool Flush(bool hardFlush, int propagation=-1, bool blocking=true) {return m_ida.Flush(hardFlush, propagation, blocking);}

protected:
    RawIDA m_ida;
    bool m_pad;
    unsigned int m_nextChannel;
};

/// \brief Rabin's Information Dispersal Algorithm
/// \details InformationDispersal is a variant of Rabin's information dispersal algorithm
/// \sa SecretRecovery, SecretRecovery, InformationDispersal, InformationRecovery
/// \since Crypto++ 1.0
class InformationRecovery : public RawIDA
{
public:
    /// \brief Construct a InformationRecovery
    InformationRecovery(int threshold, BufferedTransformation *attachment=NULLPTR, bool removePadding=true)
        : RawIDA(attachment), m_pad(false)
        {IsolatedInitialize(MakeParameters("RecoveryThreshold", threshold)("RemovePadding", removePadding));}

    void IsolatedInitialize(const NameValuePairs &parameters=g_nullNameValuePairs);

protected:
    void FlushOutputQueues();
    void OutputMessageEnds();

    bool m_pad;
    ByteQueue m_queue;
};

class PaddingRemover : public Unflushable<Filter>
{
public:
    PaddingRemover(BufferedTransformation *attachment=NULLPTR)
        : m_possiblePadding(false), m_zeroCount(0) {Detach(attachment);}

    void IsolatedInitialize(const NameValuePairs &parameters)
        {CRYPTOPP_UNUSED(parameters); m_possiblePadding = false;}
    size_t Put2(const byte *begin, size_t length, int messageEnd, bool blocking);

    // GetPossiblePadding() == false at the end of a message indicates incorrect padding
    bool GetPossiblePadding() const {return m_possiblePadding;}

private:
    bool m_possiblePadding;
    lword m_zeroCount;
};

NAMESPACE_END

#endif