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nr.h

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#ifndef CRYPTOPP_NR_H
#define CRYPTOPP_NR_H

#include "pubkey.h"
#include "modexppc.h"

#include <limits.h>

NAMESPACE_BEGIN(CryptoPP)

class NRDigestVerifier : public PK_WithPrecomputation<DigestVerifier>
{
public:
        NRDigestVerifier(const Integer &p, const Integer &q, const Integer &g, const Integer &y);
        NRDigestVerifier(BufferedTransformation &bt);

        void Precompute(unsigned int precomputationStorage=16);
        void LoadPrecomputation(BufferedTransformation &storedPrecomputation);
        void SavePrecomputation(BufferedTransformation &storedPrecomputation) const;

        void DEREncode(BufferedTransformation &bt) const;
        bool VerifyDigest(const byte *digest, unsigned int digestLen, const byte *signature) const;

        unsigned int MaxDigestLength() const {return UINT_MAX;}
        unsigned int DigestSignatureLength() const {return 2*m_q.ByteCount();}

        const Integer & GetModulus() const {return m_p;}
        const Integer & GetSubgroupSize() const {return m_q;}
        const Integer & GetGenerator() const {return m_g;}
        const Integer & GetPublicResidue() const {return m_y;}

protected:
        NRDigestVerifier() {}
        bool RawVerify(const Integer &m, const Integer &a, const Integer &b) const;
        unsigned int ExponentBitLength() const;
        Integer EncodeDigest(const byte *digest, unsigned int digestLen) const;

        Integer m_p, m_q, m_g, m_y;
        ModExpPrecomputation m_gpc, m_ypc;
};

class NRDigestSigner : public NRDigestVerifier, public PK_WithPrecomputation<DigestSigner>
{
public:
        NRDigestSigner(const Integer &p, const Integer &q, const Integer &g, const Integer &y, const Integer &x);
        NRDigestSigner(RandomNumberGenerator &rng, unsigned int pbits);
        NRDigestSigner(RandomNumberGenerator &rng, const Integer &p, const Integer &q, const Integer &g);
        NRDigestSigner(BufferedTransformation &bt);

        void DEREncode(BufferedTransformation &bt) const;
        void SignDigest(RandomNumberGenerator &rng, const byte *digest, unsigned int digestLen, byte *signature) const;

        const Integer & GetPrivateExponent() const {return m_x;}

protected:
        void RawSign(RandomNumberGenerator &rng, const Integer &m, Integer &a, Integer &b) const;

        Integer m_x;
};

template <class H>
class NRSigner : public SignerTemplate<NRDigestSigner, H>, public PK_WithPrecomputation<PK_Signer>
{
        typedef NRDigestSigner Base;
public:
        NRSigner(const Integer &p, const Integer &q, const Integer &g, const Integer &y, const Integer &x)
                : Base(p, q, g, y, x) {}

        // generate a random private key
        NRSigner(RandomNumberGenerator &rng, unsigned int keybits)
                : Base(rng, keybits) {}

        // generate a random private key, given p, q, and g
        NRSigner(RandomNumberGenerator &rng, const Integer &p, const Integer &q, const Integer &g)
                : Base(rng, p, q, g) {}

        // load a previously generated key
        NRSigner(BufferedTransformation &storedKey)
                : Base(storedKey) {}
};

template <class H>
class NRVerifier : public VerifierTemplate<NRDigestVerifier, H>, public PK_WithPrecomputation<PK_Verifier>
{
        typedef NRDigestVerifier Base;
public:
        NRVerifier(const Integer &p, const Integer &q, const Integer &g, const Integer &y)
                : Base(p, q, g, y) {}

        // create a matching public key from a private key
        NRVerifier(const NRSigner<H> &priv)
                : Base(priv) {}

        // load a previously generated key
        NRVerifier(BufferedTransformation &storedKey)
                : Base(storedKey) {}
};

NAMESPACE_END

#endif

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