source: git/src-cryptopp/pubkey.h

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

//! \file pubkey.h
//! \brief This file contains helper classes/functions for implementing public key algorithms.
//! \details The class hierachies in this header file tend to look like this:
//!
//! <pre>
//!                   x1
//!                  +--+
//!                  |  |
//!                 y1  z1
//!                  |  |
//!             x2<y1>  x2<z1>
//!                  |  |
//!                 y2  z2
//!                  |  |
//!             x3<y2>  x3<z2>
//!                  |  |
//!                 y3  z3
//! </pre>
//!
//! <ul>
//!   <li>x1, y1, z1 are abstract interface classes defined in cryptlib.h
//!   <li>x2, y2, z2 are implementations of the interfaces using "abstract policies", which
//!       are pure virtual functions that should return interfaces to interchangeable algorithms.
//!       These classes have \p Base suffixes.
//!   <li>x3, y3, z3 hold actual algorithms and implement those virtual functions.
//!       These classes have \p Impl suffixes.
//! </ul>
//!
//! \details The \p TF_ prefix means an implementation using trapdoor functions on integers.
//! \details The \p DL_ prefix means an implementation using group operations in groups where discrete log is hard.

#ifndef CRYPTOPP_PUBKEY_H
#define CRYPTOPP_PUBKEY_H

#include "config.h"

#if CRYPTOPP_MSC_VERSION
# pragma warning(push)
# pragma warning(disable: 4702)
#endif

#include "cryptlib.h"
#include "integer.h"
#include "algebra.h"
#include "modarith.h"
#include "filters.h"
#include "eprecomp.h"
#include "fips140.h"
#include "argnames.h"
#include "smartptr.h"
#include "stdcpp.h"

// VC60 workaround: this macro is defined in shlobj.h and conflicts with a template parameter used in this file
#undef INTERFACE

#if defined(__SUNPRO_CC)
# define MAYBE_RETURN(x) return x
#else
# define MAYBE_RETURN(x) CRYPTOPP_UNUSED(x)
#endif

NAMESPACE_BEGIN(CryptoPP)

//! \class TrapdoorFunctionBounds
//! \brief Provides range for plaintext and ciphertext lengths
//! \details A trapdoor function is a function that is easy to compute in one direction,
//!   but difficult to compute in the opposite direction without special knowledge.
//!   The special knowledge is usually the private key.
//! \details Trapdoor functions only handle messages of a limited length or size.
//!   \p MaxPreimage is the plaintext's maximum length, and \p MaxImage is the
//!   ciphertext's maximum length.
//! \sa TrapdoorFunctionBounds(), RandomizedTrapdoorFunction(), TrapdoorFunction(),
//!   RandomizedTrapdoorFunctionInverse() and TrapdoorFunctionInverse()
class CRYPTOPP_DLL CRYPTOPP_NO_VTABLE TrapdoorFunctionBounds
{
public:
        virtual ~TrapdoorFunctionBounds() {}

        //! \brief Returns the maximum size of a message before the trapdoor function is applied
        //! \returns the maximum size of a message before the trapdoor function is applied
        //! \details Derived classes must implement \p PreimageBound().
        virtual Integer PreimageBound() const =0;
        //! \brief Returns the maximum size of a message after the trapdoor function is applied
        //! \returns the maximum size of a message after the trapdoor function is applied
        //! \details Derived classes must implement \p ImageBound().
        virtual Integer ImageBound() const =0;
        //! \brief Returns the maximum size of a message before the trapdoor function is applied bound to a public key
        //! \returns the maximum size of a message before the trapdoor function is applied bound to a public key
        //! \details The default implementation returns <tt>PreimageBound() - 1</tt>.
        virtual Integer MaxPreimage() const {return --PreimageBound();}
        //! \brief Returns the maximum size of a message after the trapdoor function is applied bound to a public key
        //! \returns the the maximum size of a message after the trapdoor function is applied bound to a public key
        //! \details The default implementation returns <tt>ImageBound() - 1</tt>.
        virtual Integer MaxImage() const {return --ImageBound();}
};

//! \class RandomizedTrapdoorFunction
//! \brief Applies the trapdoor function, using random data if required
//! \details \p ApplyFunction() is the foundation for encrypting a message under a public key.
//!   Derived classes will override it at some point.
//! \sa TrapdoorFunctionBounds(), RandomizedTrapdoorFunction(), TrapdoorFunction(),
//!   RandomizedTrapdoorFunctionInverse() and TrapdoorFunctionInverse()
class CRYPTOPP_DLL CRYPTOPP_NO_VTABLE RandomizedTrapdoorFunction : public TrapdoorFunctionBounds
{
public:
#ifndef CRYPTOPP_MAINTAIN_BACKWARDS_COMPATIBILITY_562
        virtual ~RandomizedTrapdoorFunction() { }
#endif

        //! \brief Applies the trapdoor function, using random data if required
        //! \param rng a \p RandomNumberGenerator derived class
        //! \param x the message on which the encryption function is applied
        //! \returns the message \p x encrypted under the public key
        //! \details \p ApplyRandomizedFunction is a generalization of encryption under a public key
        //!    cryptosystem. The \p RandomNumberGenerator may (or may not) be required.
        //!    Derived classes must implement it.
        virtual Integer ApplyRandomizedFunction(RandomNumberGenerator &rng, const Integer &x) const =0;

        //! \brief Determines if the encryption algorithm is randomized
        //! \returns \p true if the encryption algorithm is randomized, \p false otherwise
        //! \details If \p IsRandomized() returns \p false, then \p NullRNG() can be used.
        virtual bool IsRandomized() const {return true;}
};

//! \class TrapdoorFunction
//! \brief Applies the trapdoor function
//! \details \p ApplyFunction() is the foundation for encrypting a message under a public key.
//!    Derived classes will override it at some point.
//! \sa TrapdoorFunctionBounds(), RandomizedTrapdoorFunction(), TrapdoorFunction(),
//!   RandomizedTrapdoorFunctionInverse() and TrapdoorFunctionInverse()
class CRYPTOPP_DLL CRYPTOPP_NO_VTABLE TrapdoorFunction : public RandomizedTrapdoorFunction
{
public:
#ifndef CRYPTOPP_MAINTAIN_BACKWARDS_COMPATIBILITY_562
        virtual ~TrapdoorFunction() { }
#endif

        //! \brief Applies the trapdoor function
        //! \param rng a \p RandomNumberGenerator derived class
        //! \param x the message on which the encryption function is applied
        //! \details \p ApplyRandomizedFunction is a generalization of encryption under a public key
        //!    cryptosystem. The \p RandomNumberGenerator may (or may not) be required.
        //! \details Internally, \p ApplyRandomizedFunction() calls \p ApplyFunction() \a
        //!   without the \p RandomNumberGenerator.
        Integer ApplyRandomizedFunction(RandomNumberGenerator &rng, const Integer &x) const
                {CRYPTOPP_UNUSED(rng); return ApplyFunction(x);}
        bool IsRandomized() const {return false;}

        //! \brief Applies the trapdoor
        //! \param x the message on which the encryption function is applied
        //! \returns the message \p x encrypted under the public key
        //! \details \p ApplyFunction is a generalization of encryption under a public key
        //!    cryptosystem. Derived classes must implement it.
        virtual Integer ApplyFunction(const Integer &x) const =0;
};

//! \class RandomizedTrapdoorFunctionInverse
//! \brief Applies the inverse of the trapdoor function, using random data if required
//! \details \p CalculateInverse() is the foundation for decrypting a message under a private key
//!   in a public key cryptosystem. Derived classes will override it at some point.
//! \sa TrapdoorFunctionBounds(), RandomizedTrapdoorFunction(), TrapdoorFunction(),
//!   RandomizedTrapdoorFunctionInverse() and TrapdoorFunctionInverse()
class CRYPTOPP_DLL CRYPTOPP_NO_VTABLE RandomizedTrapdoorFunctionInverse
{
public:
        virtual ~RandomizedTrapdoorFunctionInverse() {}

        //! \brief Applies the inverse of the trapdoor function, using random data if required
        //! \param rng a \p RandomNumberGenerator derived class
        //! \param x the message on which the decryption function is applied
        //! \returns the message \p x decrypted under the private key
        //! \details \p CalculateRandomizedInverse is a generalization of decryption using the private key
        //!    The \p RandomNumberGenerator may (or may not) be required. Derived classes must implement it.
        virtual Integer CalculateRandomizedInverse(RandomNumberGenerator &rng, const Integer &x) const =0;

        //! \brief Determines if the decryption algorithm is randomized
        //! \returns \p true if the decryption algorithm is randomized, \p false otherwise
        //! \details If \p IsRandomized() returns \p false, then \p NullRNG() can be used.
        virtual bool IsRandomized() const {return true;}
};

//! \class TrapdoorFunctionInverse
//! \brief Applies the inverse of the trapdoor function
//! \details \p CalculateInverse() is the foundation for decrypting a message under a private key
//!   in a public key cryptosystem. Derived classes will override it at some point.
//! \sa TrapdoorFunctionBounds(), RandomizedTrapdoorFunction(), TrapdoorFunction(),
//!   RandomizedTrapdoorFunctionInverse() and TrapdoorFunctionInverse()
class CRYPTOPP_DLL CRYPTOPP_NO_VTABLE TrapdoorFunctionInverse : public RandomizedTrapdoorFunctionInverse
{
public:
        virtual ~TrapdoorFunctionInverse() {}

        //! \brief Applies the inverse of the trapdoor function
        //! \param rng a \p RandomNumberGenerator derived class
        //! \param x the message on which the decryption function is applied
        //! \returns the message \p x decrypted under the private key
        //! \details \p CalculateRandomizedInverse is a generalization of decryption using the private key
        //! \details Internally, \p CalculateRandomizedInverse() calls \p CalculateInverse() \a
        //!   without the \p RandomNumberGenerator.
        Integer CalculateRandomizedInverse(RandomNumberGenerator &rng, const Integer &x) const
                {return CalculateInverse(rng, x);}

        //! \brief Determines if the decryption algorithm is randomized
        //! \returns \p true if the decryption algorithm is randomized, \p false otherwise
        //! \details If \p IsRandomized() returns \p false, then \p NullRNG() can be used.
        bool IsRandomized() const {return false;}

        //! \brief Calculates the inverse of an element
        //! \param rng a \p RandomNumberGenerator derived class
        //! \param x the element
        //! \returns the inverse of the element in the group
        virtual Integer CalculateInverse(RandomNumberGenerator &rng, const Integer &x) const =0;
};

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

//! \class PK_EncryptionMessageEncodingMethod
//! \brief Message encoding method for public key encryption
class CRYPTOPP_NO_VTABLE PK_EncryptionMessageEncodingMethod
{
public:
        virtual ~PK_EncryptionMessageEncodingMethod() {}

        virtual bool ParameterSupported(const char *name) const
                {CRYPTOPP_UNUSED(name); return false;}

        //! max size of unpadded message in bytes, given max size of padded message in bits (1 less than size of modulus)
        virtual size_t MaxUnpaddedLength(size_t paddedLength) const =0;

        virtual void Pad(RandomNumberGenerator &rng, const byte *raw, size_t inputLength, byte *padded, size_t paddedBitLength, const NameValuePairs &parameters) const =0;

        virtual DecodingResult Unpad(const byte *padded, size_t paddedBitLength, byte *raw, const NameValuePairs &parameters) const =0;
};

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

//! \class TF_Base
//! \brief The base for trapdoor based cryptosystems
//! \tparam TFI trapdoor function interface derived class
//! \tparam MEI message encoding interface derived class
template <class TFI, class MEI>
class CRYPTOPP_NO_VTABLE TF_Base
{
protected:
#ifndef CRYPTOPP_MAINTAIN_BACKWARDS_COMPATIBILITY_562
        virtual ~TF_Base() { }
#endif

        virtual const TrapdoorFunctionBounds & GetTrapdoorFunctionBounds() const =0;

        typedef TFI TrapdoorFunctionInterface;
        virtual const TrapdoorFunctionInterface & GetTrapdoorFunctionInterface() const =0;

        typedef MEI MessageEncodingInterface;
        virtual const MessageEncodingInterface & GetMessageEncodingInterface() const =0;
};

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

//! \class PK_FixedLengthCryptoSystemImpl
//! \brief Public key trapdoor function default implementation
//! \tparam BASE public key cryptosystem with a fixed length
template <class BASE>
class CRYPTOPP_NO_VTABLE PK_FixedLengthCryptoSystemImpl : public BASE
{
public:
#ifndef CRYPTOPP_MAINTAIN_BACKWARDS_COMPATIBILITY_562
        virtual ~PK_FixedLengthCryptoSystemImpl() { }
#endif

        size_t MaxPlaintextLength(size_t ciphertextLength) const
                {return ciphertextLength == FixedCiphertextLength() ? FixedMaxPlaintextLength() : 0;}
        size_t CiphertextLength(size_t plaintextLength) const
                {return plaintextLength <= FixedMaxPlaintextLength() ? FixedCiphertextLength() : 0;}

        virtual size_t FixedMaxPlaintextLength() const =0;
        virtual size_t FixedCiphertextLength() const =0;
};

//! \class TF_CryptoSystemBase
//! \brief Trapdoor function cryptosystem base class
//! \tparam INTERFACE public key cryptosystem base interface
//! \tparam BASE public key cryptosystem implementation base
template <class INTERFACE, class BASE>
class CRYPTOPP_NO_VTABLE TF_CryptoSystemBase : public PK_FixedLengthCryptoSystemImpl<INTERFACE>, protected BASE
{
public:
#ifndef CRYPTOPP_MAINTAIN_BACKWARDS_COMPATIBILITY_562
        virtual ~TF_CryptoSystemBase() { }
#endif

        bool ParameterSupported(const char *name) const {return this->GetMessageEncodingInterface().ParameterSupported(name);}
        size_t FixedMaxPlaintextLength() const {return this->GetMessageEncodingInterface().MaxUnpaddedLength(PaddedBlockBitLength());}
        size_t FixedCiphertextLength() const {return this->GetTrapdoorFunctionBounds().MaxImage().ByteCount();}

protected:
        size_t PaddedBlockByteLength() const {return BitsToBytes(PaddedBlockBitLength());}
        // Coverity finding on potential overflow/underflow.
        size_t PaddedBlockBitLength() const {return SaturatingSubtract(this->GetTrapdoorFunctionBounds().PreimageBound().BitCount(),1U);}
};

//! \class TF_DecryptorBase
//! \brief Trapdoor function cryptosystems decryption base class
class CRYPTOPP_DLL CRYPTOPP_NO_VTABLE TF_DecryptorBase : public TF_CryptoSystemBase<PK_Decryptor, TF_Base<TrapdoorFunctionInverse, PK_EncryptionMessageEncodingMethod> >
{
public:
#ifndef CRYPTOPP_MAINTAIN_BACKWARDS_COMPATIBILITY_562
        virtual ~TF_DecryptorBase() { }
#endif

        DecodingResult Decrypt(RandomNumberGenerator &rng, const byte *ciphertext, size_t ciphertextLength, byte *plaintext, const NameValuePairs &parameters = g_nullNameValuePairs) const;
};

//! \class TF_DecryptorBase
//! \brief Trapdoor function cryptosystems encryption base class
class CRYPTOPP_DLL CRYPTOPP_NO_VTABLE TF_EncryptorBase : public TF_CryptoSystemBase<PK_Encryptor, TF_Base<RandomizedTrapdoorFunction, PK_EncryptionMessageEncodingMethod> >
{
public:
#ifndef CRYPTOPP_MAINTAIN_BACKWARDS_COMPATIBILITY_562
        virtual ~TF_EncryptorBase() { }
#endif

        void Encrypt(RandomNumberGenerator &rng, const byte *plaintext, size_t plaintextLength, byte *ciphertext, const NameValuePairs &parameters = g_nullNameValuePairs) const;
};

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

// Typedef change due to Clang, http://github.com/weidai11/cryptopp/issues/300
typedef std::pair<const byte *, unsigned int> HashIdentifier;

//! \class PK_SignatureMessageEncodingMethod
//! \brief Interface for message encoding method for public key signature schemes.
//! \details \p PK_SignatureMessageEncodingMethod provides interfaces for message
//!   encoding method for public key signature schemes. The methods support both
//!   trapdoor functions (<tt>TF_*</tt>) and discrete logarithm (<tt>DL_*</tt>)
//!   based schemes.
class CRYPTOPP_NO_VTABLE PK_SignatureMessageEncodingMethod
{
public:
        virtual ~PK_SignatureMessageEncodingMethod() {}

        virtual size_t MinRepresentativeBitLength(size_t hashIdentifierLength, size_t digestLength) const
                {CRYPTOPP_UNUSED(hashIdentifierLength); CRYPTOPP_UNUSED(digestLength); return 0;}
        virtual size_t MaxRecoverableLength(size_t representativeBitLength, size_t hashIdentifierLength, size_t digestLength) const
                {CRYPTOPP_UNUSED(representativeBitLength); CRYPTOPP_UNUSED(representativeBitLength); CRYPTOPP_UNUSED(hashIdentifierLength); CRYPTOPP_UNUSED(digestLength); return 0;}

        bool IsProbabilistic() const
                {return true;}
        bool AllowNonrecoverablePart() const
                {throw NotImplemented("PK_MessageEncodingMethod: this signature scheme does not support message recovery");}
        virtual bool RecoverablePartFirst() const
                {throw NotImplemented("PK_MessageEncodingMethod: this signature scheme does not support message recovery");}

        // for verification, DL
        virtual void ProcessSemisignature(HashTransformation &hash, const byte *semisignature, size_t semisignatureLength) const
                {CRYPTOPP_UNUSED(hash); CRYPTOPP_UNUSED(semisignature); CRYPTOPP_UNUSED(semisignatureLength);}

        // for signature
        virtual void ProcessRecoverableMessage(HashTransformation &hash,
                const byte *recoverableMessage, size_t recoverableMessageLength,
                const byte *presignature, size_t presignatureLength,
                SecByteBlock &semisignature) const
        {
                CRYPTOPP_UNUSED(hash);CRYPTOPP_UNUSED(recoverableMessage); CRYPTOPP_UNUSED(recoverableMessageLength);
                CRYPTOPP_UNUSED(presignature); CRYPTOPP_UNUSED(presignatureLength); CRYPTOPP_UNUSED(semisignature);
                if (RecoverablePartFirst())
                        CRYPTOPP_ASSERT(!"ProcessRecoverableMessage() not implemented");
        }

        virtual void ComputeMessageRepresentative(RandomNumberGenerator &rng,
                const byte *recoverableMessage, size_t recoverableMessageLength,
                HashTransformation &hash, HashIdentifier hashIdentifier, bool messageEmpty,
                byte *representative, size_t representativeBitLength) const =0;

        virtual bool VerifyMessageRepresentative(
                HashTransformation &hash, HashIdentifier hashIdentifier, bool messageEmpty,
                byte *representative, size_t representativeBitLength) const =0;

        virtual DecodingResult RecoverMessageFromRepresentative(        // for TF
                HashTransformation &hash, HashIdentifier hashIdentifier, bool messageEmpty,
                byte *representative, size_t representativeBitLength,
                byte *recoveredMessage) const
                {CRYPTOPP_UNUSED(hash);CRYPTOPP_UNUSED(hashIdentifier); CRYPTOPP_UNUSED(messageEmpty);
                CRYPTOPP_UNUSED(representative); CRYPTOPP_UNUSED(representativeBitLength); CRYPTOPP_UNUSED(recoveredMessage);
                throw NotImplemented("PK_MessageEncodingMethod: this signature scheme does not support message recovery");}

        virtual DecodingResult RecoverMessageFromSemisignature(         // for DL
                HashTransformation &hash, HashIdentifier hashIdentifier,
                const byte *presignature, size_t presignatureLength,
                const byte *semisignature, size_t semisignatureLength,
                byte *recoveredMessage) const
                {CRYPTOPP_UNUSED(hash);CRYPTOPP_UNUSED(hashIdentifier); CRYPTOPP_UNUSED(presignature); CRYPTOPP_UNUSED(presignatureLength);
                CRYPTOPP_UNUSED(semisignature); CRYPTOPP_UNUSED(semisignatureLength); CRYPTOPP_UNUSED(recoveredMessage);
                throw NotImplemented("PK_MessageEncodingMethod: this signature scheme does not support message recovery");}

        // VC60 workaround
        struct HashIdentifierLookup
        {
                template <class H> struct HashIdentifierLookup2
                {
                        static HashIdentifier CRYPTOPP_API Lookup()
                        {
                                return HashIdentifier((const byte *)NULL, 0);
                        }
                };
        };
};

//! \class PK_DeterministicSignatureMessageEncodingMethod
//! \brief Interface for message encoding method for public key signature schemes.
//! \details \p PK_DeterministicSignatureMessageEncodingMethod provides interfaces
//!   for message encoding method for public key signature schemes.
class CRYPTOPP_DLL CRYPTOPP_NO_VTABLE PK_DeterministicSignatureMessageEncodingMethod : public PK_SignatureMessageEncodingMethod
{
public:
        bool VerifyMessageRepresentative(
                HashTransformation &hash, HashIdentifier hashIdentifier, bool messageEmpty,
                byte *representative, size_t representativeBitLength) const;
};

//! \class PK_RecoverableSignatureMessageEncodingMethod
//! \brief Interface for message encoding method for public key signature schemes.
//! \details \p PK_RecoverableSignatureMessageEncodingMethod provides interfaces
//!   for message encoding method for public key signature schemes.
class CRYPTOPP_DLL CRYPTOPP_NO_VTABLE PK_RecoverableSignatureMessageEncodingMethod : public PK_SignatureMessageEncodingMethod
{
public:
        bool VerifyMessageRepresentative(
                HashTransformation &hash, HashIdentifier hashIdentifier, bool messageEmpty,
                byte *representative, size_t representativeBitLength) const;
};

//! \class DL_SignatureMessageEncodingMethod_DSA
//! \brief Interface for message encoding method for public key signature schemes.
//! \details \p DL_SignatureMessageEncodingMethod_DSA provides interfaces
//!   for message encoding method for DSA.
class CRYPTOPP_DLL DL_SignatureMessageEncodingMethod_DSA : public PK_DeterministicSignatureMessageEncodingMethod
{
public:
        void ComputeMessageRepresentative(RandomNumberGenerator &rng,
                const byte *recoverableMessage, size_t recoverableMessageLength,
                HashTransformation &hash, HashIdentifier hashIdentifier, bool messageEmpty,
                byte *representative, size_t representativeBitLength) const;
};

//! \class DL_SignatureMessageEncodingMethod_NR
//! \brief Interface for message encoding method for public key signature schemes.
//! \details \p DL_SignatureMessageEncodingMethod_NR provides interfaces
//!   for message encoding method for Nyberg-Rueppel.
class CRYPTOPP_DLL DL_SignatureMessageEncodingMethod_NR : public PK_DeterministicSignatureMessageEncodingMethod
{
public:
        void ComputeMessageRepresentative(RandomNumberGenerator &rng,
                const byte *recoverableMessage, size_t recoverableMessageLength,
                HashTransformation &hash, HashIdentifier hashIdentifier, bool messageEmpty,
                byte *representative, size_t representativeBitLength) const;
};

//! \class PK_MessageAccumulatorBase
//! \brief Interface for message encoding method for public key signature schemes.
//! \details \p PK_MessageAccumulatorBase provides interfaces
//!   for message encoding method.
class CRYPTOPP_DLL CRYPTOPP_NO_VTABLE PK_MessageAccumulatorBase : public PK_MessageAccumulator
{
public:
        PK_MessageAccumulatorBase() : m_empty(true) {}

        virtual HashTransformation & AccessHash() =0;

        void Update(const byte *input, size_t length)
        {
                AccessHash().Update(input, length);
                m_empty = m_empty && length == 0;
        }

        SecByteBlock m_recoverableMessage, m_representative, m_presignature, m_semisignature;
        Integer m_k, m_s;
        bool m_empty;
};

//! \class PK_MessageAccumulatorImpl
//! \brief Interface for message encoding method for public key signature schemes.
//! \details \p PK_MessageAccumulatorBase provides interfaces
//!   for message encoding method.
template <class HASH_ALGORITHM>
class PK_MessageAccumulatorImpl : public PK_MessageAccumulatorBase, protected ObjectHolder<HASH_ALGORITHM>
{
public:
        HashTransformation & AccessHash() {return this->m_object;}
};

//! _
template <class INTERFACE, class BASE>
class CRYPTOPP_NO_VTABLE TF_SignatureSchemeBase : public INTERFACE, protected BASE
{
public:
#ifndef CRYPTOPP_MAINTAIN_BACKWARDS_COMPATIBILITY_562
        virtual ~TF_SignatureSchemeBase() { }
#endif

        size_t SignatureLength() const
                {return this->GetTrapdoorFunctionBounds().MaxPreimage().ByteCount();}
        size_t MaxRecoverableLength() const
                {return this->GetMessageEncodingInterface().MaxRecoverableLength(MessageRepresentativeBitLength(), GetHashIdentifier().second, GetDigestSize());}
        size_t MaxRecoverableLengthFromSignatureLength(size_t signatureLength) const
                {CRYPTOPP_UNUSED(signatureLength); return this->MaxRecoverableLength();}

        bool IsProbabilistic() const
                {return this->GetTrapdoorFunctionInterface().IsRandomized() || this->GetMessageEncodingInterface().IsProbabilistic();}
        bool AllowNonrecoverablePart() const
                {return this->GetMessageEncodingInterface().AllowNonrecoverablePart();}
        bool RecoverablePartFirst() const
                {return this->GetMessageEncodingInterface().RecoverablePartFirst();}

protected:
        size_t MessageRepresentativeLength() const {return BitsToBytes(MessageRepresentativeBitLength());}
        // Coverity finding on potential overflow/underflow.
        size_t MessageRepresentativeBitLength() const {return SaturatingSubtract(this->GetTrapdoorFunctionBounds().ImageBound().BitCount(),1U);}
        virtual HashIdentifier GetHashIdentifier() const =0;
        virtual size_t GetDigestSize() const =0;
};

//! _
class CRYPTOPP_DLL CRYPTOPP_NO_VTABLE TF_SignerBase : public TF_SignatureSchemeBase<PK_Signer, TF_Base<RandomizedTrapdoorFunctionInverse, PK_SignatureMessageEncodingMethod> >
{
public:
#ifndef CRYPTOPP_MAINTAIN_BACKWARDS_COMPATIBILITY_562
        virtual ~TF_SignerBase() { }
#endif

        void InputRecoverableMessage(PK_MessageAccumulator &messageAccumulator, const byte *recoverableMessage, size_t recoverableMessageLength) const;
        size_t SignAndRestart(RandomNumberGenerator &rng, PK_MessageAccumulator &messageAccumulator, byte *signature, bool restart=true) const;
};

//! _
class CRYPTOPP_DLL CRYPTOPP_NO_VTABLE TF_VerifierBase : public TF_SignatureSchemeBase<PK_Verifier, TF_Base<TrapdoorFunction, PK_SignatureMessageEncodingMethod> >
{
public:
#ifndef CRYPTOPP_MAINTAIN_BACKWARDS_COMPATIBILITY_562
        virtual ~TF_VerifierBase() { }
#endif

        void InputSignature(PK_MessageAccumulator &messageAccumulator, const byte *signature, size_t signatureLength) const;
        bool VerifyAndRestart(PK_MessageAccumulator &messageAccumulator) const;
        DecodingResult RecoverAndRestart(byte *recoveredMessage, PK_MessageAccumulator &recoveryAccumulator) const;
};

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

//! _
template <class T1, class T2, class T3>
struct TF_CryptoSchemeOptions
{
        typedef T1 AlgorithmInfo;
        typedef T2 Keys;
        typedef typename Keys::PrivateKey PrivateKey;
        typedef typename Keys::PublicKey PublicKey;
        typedef T3 MessageEncodingMethod;
};

//! _
template <class T1, class T2, class T3, class T4>
struct TF_SignatureSchemeOptions : public TF_CryptoSchemeOptions<T1, T2, T3>
{
        typedef T4 HashFunction;
};

//! _
template <class BASE, class SCHEME_OPTIONS, class KEY_CLASS>
class CRYPTOPP_NO_VTABLE TF_ObjectImplBase : public AlgorithmImpl<BASE, typename SCHEME_OPTIONS::AlgorithmInfo>
{
public:
        typedef SCHEME_OPTIONS SchemeOptions;
        typedef KEY_CLASS KeyClass;

#ifndef CRYPTOPP_MAINTAIN_BACKWARDS_COMPATIBILITY_562
        virtual ~TF_ObjectImplBase() { }
#endif

        PublicKey & AccessPublicKey() {return AccessKey();}
        const PublicKey & GetPublicKey() const {return GetKey();}

        PrivateKey & AccessPrivateKey() {return AccessKey();}
        const PrivateKey & GetPrivateKey() const {return GetKey();}

        virtual const KeyClass & GetKey() const =0;
        virtual KeyClass & AccessKey() =0;

        const KeyClass & GetTrapdoorFunction() const {return GetKey();}

        PK_MessageAccumulator * NewSignatureAccumulator(RandomNumberGenerator &rng) const
        {
                CRYPTOPP_UNUSED(rng);
                return new PK_MessageAccumulatorImpl<CPP_TYPENAME SCHEME_OPTIONS::HashFunction>;
        }
        PK_MessageAccumulator * NewVerificationAccumulator() const
        {
                return new PK_MessageAccumulatorImpl<CPP_TYPENAME SCHEME_OPTIONS::HashFunction>;
        }

protected:
        const typename BASE::MessageEncodingInterface & GetMessageEncodingInterface() const
                {return Singleton<CPP_TYPENAME SCHEME_OPTIONS::MessageEncodingMethod>().Ref();}
        const TrapdoorFunctionBounds & GetTrapdoorFunctionBounds() const
                {return GetKey();}
        const typename BASE::TrapdoorFunctionInterface & GetTrapdoorFunctionInterface() const
                {return GetKey();}

        // for signature scheme
        HashIdentifier GetHashIdentifier() const
        {
        typedef CPP_TYPENAME SchemeOptions::MessageEncodingMethod::HashIdentifierLookup::template HashIdentifierLookup2<CPP_TYPENAME SchemeOptions::HashFunction> L;
        return L::Lookup();
        }
        size_t GetDigestSize() const
        {
                typedef CPP_TYPENAME SchemeOptions::HashFunction H;
                return H::DIGESTSIZE;
        }
};

//! _
template <class BASE, class SCHEME_OPTIONS, class KEY>
class TF_ObjectImplExtRef : public TF_ObjectImplBase<BASE, SCHEME_OPTIONS, KEY>
{
public:
#ifndef CRYPTOPP_MAINTAIN_BACKWARDS_COMPATIBILITY_562
        virtual ~TF_ObjectImplExtRef() { }
#endif

        TF_ObjectImplExtRef(const KEY *pKey = NULL) : m_pKey(pKey) {}
        void SetKeyPtr(const KEY *pKey) {m_pKey = pKey;}

        const KEY & GetKey() const {return *m_pKey;}
        KEY & AccessKey() {throw NotImplemented("TF_ObjectImplExtRef: cannot modify refererenced key");}

private:
        const KEY * m_pKey;
};

//! _
template <class BASE, class SCHEME_OPTIONS, class KEY_CLASS>
class CRYPTOPP_NO_VTABLE TF_ObjectImpl : public TF_ObjectImplBase<BASE, SCHEME_OPTIONS, KEY_CLASS>
{
public:
        typedef KEY_CLASS KeyClass;

#ifndef CRYPTOPP_MAINTAIN_BACKWARDS_COMPATIBILITY_562
        virtual ~TF_ObjectImpl() { }
#endif

        const KeyClass & GetKey() const {return m_trapdoorFunction;}
        KeyClass & AccessKey() {return m_trapdoorFunction;}

private:
        KeyClass m_trapdoorFunction;
};

//! _
template <class SCHEME_OPTIONS>
class TF_DecryptorImpl : public TF_ObjectImpl<TF_DecryptorBase, SCHEME_OPTIONS, typename SCHEME_OPTIONS::PrivateKey>
{
};

//! _
template <class SCHEME_OPTIONS>
class TF_EncryptorImpl : public TF_ObjectImpl<TF_EncryptorBase, SCHEME_OPTIONS, typename SCHEME_OPTIONS::PublicKey>
{
};

//! _
template <class SCHEME_OPTIONS>
class TF_SignerImpl : public TF_ObjectImpl<TF_SignerBase, SCHEME_OPTIONS, typename SCHEME_OPTIONS::PrivateKey>
{
};

//! _
template <class SCHEME_OPTIONS>
class TF_VerifierImpl : public TF_ObjectImpl<TF_VerifierBase, SCHEME_OPTIONS, typename SCHEME_OPTIONS::PublicKey>
{
};

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

//! \class MaskGeneratingFunction
//! \brief Mask generation function interface
class CRYPTOPP_NO_VTABLE MaskGeneratingFunction
{
public:
        virtual ~MaskGeneratingFunction() {}

        //! \brief Generate and apply mask
        //! \param hash HashTransformation derived class
        //! \param output the destination byte array
        //! \param outputLength the size fo the the destination byte array
        //! \param input the message to hash
        //! \param inputLength the size of the message
        //! \param mask flag indicating whether to apply the mask
        virtual void GenerateAndMask(HashTransformation &hash, byte *output, size_t outputLength, const byte *input, size_t inputLength, bool mask = true) const =0;
};

//! \fn P1363_MGF1KDF2_Common
//! \brief P1363 mask generation function
//! \param hash HashTransformation derived class
//! \param output the destination byte array
//! \param outputLength the size fo the the destination byte array
//! \param input the message to hash
//! \param inputLength the size of the message
//! \param derivationParams additional derivation parameters
//! \param derivationParamsLength the size of the additional derivation parameters
//! \param mask flag indicating whether to apply the mask
//! \param counterStart starting counter value used in generation function
CRYPTOPP_DLL void CRYPTOPP_API P1363_MGF1KDF2_Common(HashTransformation &hash, byte *output, size_t outputLength, const byte *input, size_t inputLength, const byte *derivationParams, size_t derivationParamsLength, bool mask, unsigned int counterStart);

//! \class P1363_MGF1
//! \brief P1363 mask generation function
class P1363_MGF1 : public MaskGeneratingFunction
{
public:
        CRYPTOPP_CONSTEXPR static const char * CRYPTOPP_API StaticAlgorithmName() {return "MGF1";}
        void GenerateAndMask(HashTransformation &hash, byte *output, size_t outputLength, const byte *input, size_t inputLength, bool mask = true) const
        {
                P1363_MGF1KDF2_Common(hash, output, outputLength, input, inputLength, NULL, 0, mask, 0);
        }
};

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

//! \class MaskGeneratingFunction
//! \brief P1363 key derivation function
//! \tparam H hash function used in the derivation
template <class H>
class P1363_KDF2
{
public:
        static void CRYPTOPP_API DeriveKey(byte *output, size_t outputLength, const byte *input, size_t inputLength, const byte *derivationParams, size_t derivationParamsLength)
        {
                H h;
                P1363_MGF1KDF2_Common(h, output, outputLength, input, inputLength, derivationParams, derivationParamsLength, false, 1);
        }
};

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

//! \brief Exception thrown when an invalid group element is encountered
//! \details Thrown by DecodeElement and AgreeWithStaticPrivateKey
class DL_BadElement : public InvalidDataFormat
{
public:
        DL_BadElement() : InvalidDataFormat("CryptoPP: invalid group element") {}
};

//! \brief Interface for Discrete Log (DL) group parameters
//! \tparam T element in the group
//! \details The element is usually an Integer, \ref ECP "ECP::Point" or \ref EC2N "EC2N::Point"
template <class T>
class CRYPTOPP_NO_VTABLE DL_GroupParameters : public CryptoParameters
{
        typedef DL_GroupParameters<T> ThisClass;

public:
        typedef T Element;

#ifndef CRYPTOPP_MAINTAIN_BACKWARDS_COMPATIBILITY_562
        virtual ~DL_GroupParameters() { }
#endif

        DL_GroupParameters() : m_validationLevel(0) {}

        // CryptoMaterial
        bool Validate(RandomNumberGenerator &rng, unsigned int level) const
        {
                if (!GetBasePrecomputation().IsInitialized())
                        return false;

                if (m_validationLevel > level)
                        return true;

                bool pass = ValidateGroup(rng, level);
                pass = pass && ValidateElement(level, GetSubgroupGenerator(), &GetBasePrecomputation());

                m_validationLevel = pass ? level+1 : 0;

                return pass;
        }

        bool GetVoidValue(const char *name, const std::type_info &valueType, void *pValue) const
        {
                return GetValueHelper(this, name, valueType, pValue)
                        CRYPTOPP_GET_FUNCTION_ENTRY(SubgroupOrder)
                        CRYPTOPP_GET_FUNCTION_ENTRY(SubgroupGenerator)
                        ;
        }

        bool SupportsPrecomputation() const {return true;}

        void Precompute(unsigned int precomputationStorage=16)
        {
                AccessBasePrecomputation().Precompute(GetGroupPrecomputation(), GetSubgroupOrder().BitCount(), precomputationStorage);
        }

        void LoadPrecomputation(BufferedTransformation &storedPrecomputation)
        {
                AccessBasePrecomputation().Load(GetGroupPrecomputation(), storedPrecomputation);
                m_validationLevel = 0;
        }

        void SavePrecomputation(BufferedTransformation &storedPrecomputation) const
        {
                GetBasePrecomputation().Save(GetGroupPrecomputation(), storedPrecomputation);
        }

        //! \brief Retrieves the subgroup generator
        //! \return the subgroup generator
        //! \details The subgroup generator is retrieved from the base precomputation
        virtual const Element & GetSubgroupGenerator() const {return GetBasePrecomputation().GetBase(GetGroupPrecomputation());}

        //! \brief Set the subgroup generator
        //! \param base the new subgroup generator
        //! \details The subgroup generator is set in the base precomputation
        virtual void SetSubgroupGenerator(const Element &base) {AccessBasePrecomputation().SetBase(GetGroupPrecomputation(), base);}

        //! \brief Retrieves the subgroup generator
        //! \return the subgroup generator
        //! \details The subgroup generator is retrieved from the base precomputation.
        virtual Element ExponentiateBase(const Integer &exponent) const
        {
                return GetBasePrecomputation().Exponentiate(GetGroupPrecomputation(), exponent);
        }

        //! \brief Exponentiates an element
        //! \param base the base elemenet
        //! \param exponent the exponent to raise the base
        //! \return the result of the exponentiation
        //! \details Internally, ExponentiateElement() calls SimultaneousExponentiate().
        virtual Element ExponentiateElement(const Element &base, const Integer &exponent) const
        {
                Element result;
                SimultaneousExponentiate(&result, base, &exponent, 1);
                return result;
        }

        //! \brief Retrieves the group precomputation
        //! \return a const reference to the group precomputation
        virtual const DL_GroupPrecomputation<Element> & GetGroupPrecomputation() const =0;

        //! \brief Retrieves the group precomputation
        //! \return a const reference to the group precomputation using a fixed base
        virtual const DL_FixedBasePrecomputation<Element> & GetBasePrecomputation() const =0;

        //! \brief Retrieves the group precomputation
        //! \return a non-const reference to the group precomputation using a fixed base
        virtual DL_FixedBasePrecomputation<Element> & AccessBasePrecomputation() =0;

        //! \brief Retrieves the subgroup order
        //! \return the order of subgroup generated by the base element
        virtual const Integer & GetSubgroupOrder() const =0;

        //! \brief Retrieves the maximum exponent for the group
        //! \return the maximum exponent for the group
        virtual Integer GetMaxExponent() const =0;

        //! \brief Retrieves the order of the group
        //! \return the order of the group
        //! \details Either GetGroupOrder() or GetCofactor() must be overriden in a derived class.
        virtual Integer GetGroupOrder() const {return GetSubgroupOrder()*GetCofactor();}

        //! \brief Retrieves the cofactor
        //! \return the cofactor
        //! \details Either GetGroupOrder() or GetCofactor() must be overriden in a derived class.
        virtual Integer GetCofactor() const {return GetGroupOrder()/GetSubgroupOrder();}

        //! \brief Retrieves the encoded element's size
        //! \param reversible flag indicating the encoding format
        //! \return encoded element's size, in bytes
        //! \details The format of the encoded element varies by the underlyinhg type of the element and the
        //!   reversible flag. GetEncodedElementSize() must be implemented in a derived class.
        //! \sa GetEncodedElementSize(), EncodeElement(), DecodeElement()
        virtual unsigned int GetEncodedElementSize(bool reversible) const =0;

        //! \brief Encodes the element
        //! \param reversible flag indicating the encoding format
        //! \param element reference to the element to encode
        //! \param encoded destination byte array for the encoded element
        //! \details EncodeElement() must be implemented in a derived class.
        //! \pre <tt>COUNTOF(encoded) == GetEncodedElementSize()</tt>
        virtual void EncodeElement(bool reversible, const Element &element, byte *encoded) const =0;

        //! \brief Decodes the element
        //! \param encoded byte array with the encoded element
        //! \param checkForGroupMembership flag indicating if the element should be validated
        //! \return Element after decoding
        //! \details DecodeElement() must be implemented in a derived class.
        //! \pre <tt>COUNTOF(encoded) == GetEncodedElementSize()</tt>
        virtual Element DecodeElement(const byte *encoded, bool checkForGroupMembership) const =0;

        //! \brief Converts an element to an Integer
        //! \param element the element to convert to an Integer
        //! \return Element after converting to an Integer
        //! \details ConvertElementToInteger() must be implemented in a derived class.
        virtual Integer ConvertElementToInteger(const Element &element) const =0;

        //! \brief Check the group for errors
        //! \param rng RandomNumberGenerator for objects which use randomized testing
        //! \param level level of thoroughness
        //! \return true if the tests succeed, false otherwise
        //! \details There are four levels of thoroughness:
        //!   <ul>
        //!   <li>0 - using this object won't cause a crash or exception
        //!   <li>1 - this object will probably function, and encrypt, sign, other operations correctly
        //!   <li>2 - ensure this object will function correctly, and perform reasonable security checks
        //!   <li>3 - perform reasonable security checks, and do checks that may take a long time
        //!   </ul>
        //! \details Level 0 does not require a RandomNumberGenerator. A NullRNG() can be used for level 0.
        //!   Level 1 may not check for weak keys and such. Levels 2 and 3 are recommended.
        //! \details ValidateGroup() must be implemented in a derived class.
        virtual bool ValidateGroup(RandomNumberGenerator &rng, unsigned int level) const =0;

        //! \brief Check the element for errors
        //! \param level level of thoroughness
        //! \param element element to check
        //! \param precomp optional pointer to DL_FixedBasePrecomputation
        //! \return true if the tests succeed, false otherwise
        //! \details There are four levels of thoroughness:
        //!   <ul>
        //!   <li>0 - using this object won't cause a crash or exception
        //!   <li>1 - this object will probably function, and encrypt, sign, other operations correctly
        //!   <li>2 - ensure this object will function correctly, and perform reasonable security checks
        //!   <li>3 - perform reasonable security checks, and do checks that may take a long time
        //!   </ul>
        //! \details Level 0 performs group membership checks. Level 1 may not check for weak keys and such.
        //!   Levels 2 and 3 are recommended.
        //! \details ValidateElement() must be implemented in a derived class.
        virtual bool ValidateElement(unsigned int level, const Element &element, const DL_FixedBasePrecomputation<Element> *precomp) const =0;

        virtual bool FastSubgroupCheckAvailable() const =0;

        //! \brief Determines if an element is an identity
        //! \param element element to check
        //! \return true if the element is an identity, false otherwise
        //! \details The identity element or or neutral element is a special element in a group that leaves
        //!   other elements unchanged when combined with it.
        //! \details IsIdentity() must be implemented in a derived class.
        virtual bool IsIdentity(const Element &element) const =0;

        //! \brief Exponentiates a base to multiple exponents
        //! \param results an array of Elements
        //! \param base the base to raise to the exponents
        //! \param exponents an array of exponents
        //! \param exponentsCount the number of exponents in the array
        //! \details SimultaneousExponentiate() raises the base to each exponent in the exponents array and stores the
        //!   result at the respective position in the results array.
        //! \details SimultaneousExponentiate() must be implemented in a derived class.
        //! \pre <tt>COUNTOF(results) == exponentsCount</tt>
        //! \pre <tt>COUNTOF(exponents) == exponentsCount</tt>
        virtual void SimultaneousExponentiate(Element *results, const Element &base, const Integer *exponents, unsigned int exponentsCount) const =0;

protected:
        void ParametersChanged() {m_validationLevel = 0;}

private:
        mutable unsigned int m_validationLevel;
};

//! \brief Base implmentation of Discrete Log (DL) group parameters
//! \tparam GROUP_PRECOMP group precomputation class
//! \tparam BASE_PRECOMP fixed base precomputation class
//! \tparam BASE class or type of an element
template <class GROUP_PRECOMP, class BASE_PRECOMP = DL_FixedBasePrecomputationImpl<CPP_TYPENAME GROUP_PRECOMP::Element>, class BASE = DL_GroupParameters<CPP_TYPENAME GROUP_PRECOMP::Element> >
class DL_GroupParametersImpl : public BASE
{
public:
        typedef GROUP_PRECOMP GroupPrecomputation;
        typedef typename GROUP_PRECOMP::Element Element;
        typedef BASE_PRECOMP BasePrecomputation;

#ifndef CRYPTOPP_MAINTAIN_BACKWARDS_COMPATIBILITY_562
        virtual ~DL_GroupParametersImpl() { }
#endif

        //! \brief Retrieves the group precomputation
        //! \return a const reference to the group precomputation
        const DL_GroupPrecomputation<Element> & GetGroupPrecomputation() const {return m_groupPrecomputation;}

        //! \brief Retrieves the group precomputation
        //! \return a const reference to the group precomputation using a fixed base
        const DL_FixedBasePrecomputation<Element> & GetBasePrecomputation() const {return m_gpc;}

        //! \brief Retrieves the group precomputation
        //! \return a non-const reference to the group precomputation using a fixed base
        DL_FixedBasePrecomputation<Element> & AccessBasePrecomputation() {return m_gpc;}

protected:
        GROUP_PRECOMP m_groupPrecomputation;
        BASE_PRECOMP m_gpc;
};

//! \brief Base class for a Discrete Log (DL) key
//! \tparam T class or type of an element
//! \details The element is usually an Integer, \ref ECP "ECP::Point" or \ref EC2N "EC2N::Point"
template <class T>
class CRYPTOPP_NO_VTABLE DL_Key
{
public:
#ifndef CRYPTOPP_MAINTAIN_BACKWARDS_COMPATIBILITY_562
        virtual ~DL_Key() { }
#endif

        //! \brief Retrieves abstract group parameters
        //! \return a const reference to the group parameters
        virtual const DL_GroupParameters<T> & GetAbstractGroupParameters() const =0;
        //! \brief Retrieves abstract group parameters
        //! \return a non-const reference to the group parameters
        virtual DL_GroupParameters<T> & AccessAbstractGroupParameters() =0;
};

//! \brief Interface for Discrete Log (DL) public keys
template <class T>
class CRYPTOPP_NO_VTABLE DL_PublicKey : public DL_Key<T>
{
        typedef DL_PublicKey<T> ThisClass;

public:
        typedef T Element;

#ifndef CRYPTOPP_MAINTAIN_BACKWARDS_COMPATIBILITY_562
        virtual ~DL_PublicKey() { }
#endif

        bool GetVoidValue(const char *name, const std::type_info &valueType, void *pValue) const
        {
                return GetValueHelper(this, name, valueType, pValue, &this->GetAbstractGroupParameters())
                                CRYPTOPP_GET_FUNCTION_ENTRY(PublicElement);
        }

        void AssignFrom(const NameValuePairs &source);

        // non-inherited
        virtual const Element & GetPublicElement() const {return GetPublicPrecomputation().GetBase(this->GetAbstractGroupParameters().GetGroupPrecomputation());}
        virtual void SetPublicElement(const Element &y) {AccessPublicPrecomputation().SetBase(this->GetAbstractGroupParameters().GetGroupPrecomputation(), y);}
        virtual Element ExponentiatePublicElement(const Integer &exponent) const
        {
                const DL_GroupParameters<T> &params = this->GetAbstractGroupParameters();
                return GetPublicPrecomputation().Exponentiate(params.GetGroupPrecomputation(), exponent);
        }
        virtual Element CascadeExponentiateBaseAndPublicElement(const Integer &baseExp, const Integer &publicExp) const
        {
                const DL_GroupParameters<T> &params = this->GetAbstractGroupParameters();
                return params.GetBasePrecomputation().CascadeExponentiate(params.GetGroupPrecomputation(), baseExp, GetPublicPrecomputation(), publicExp);
        }

        virtual const DL_FixedBasePrecomputation<T> & GetPublicPrecomputation() const =0;
        virtual DL_FixedBasePrecomputation<T> & AccessPublicPrecomputation() =0;
};

//! \brief Interface for Discrete Log (DL) private keys
template <class T>
class CRYPTOPP_NO_VTABLE DL_PrivateKey : public DL_Key<T>
{
        typedef DL_PrivateKey<T> ThisClass;

public:
        typedef T Element;

#ifndef CRYPTOPP_MAINTAIN_BACKWARDS_COMPATIBILITY_562
        virtual ~DL_PrivateKey() { }
#endif

        void MakePublicKey(DL_PublicKey<T> &pub) const
        {
                pub.AccessAbstractGroupParameters().AssignFrom(this->GetAbstractGroupParameters());
                pub.SetPublicElement(this->GetAbstractGroupParameters().ExponentiateBase(GetPrivateExponent()));
        }

        bool GetVoidValue(const char *name, const std::type_info &valueType, void *pValue) const
        {
                return GetValueHelper(this, name, valueType, pValue, &this->GetAbstractGroupParameters())
                                CRYPTOPP_GET_FUNCTION_ENTRY(PrivateExponent);
        }

        void AssignFrom(const NameValuePairs &source)
        {
                this->AccessAbstractGroupParameters().AssignFrom(source);
                AssignFromHelper(this, source)
                        CRYPTOPP_SET_FUNCTION_ENTRY(PrivateExponent);
        }

        virtual const Integer & GetPrivateExponent() const =0;
        virtual void SetPrivateExponent(const Integer &x) =0;
};

template <class T>
void DL_PublicKey<T>::AssignFrom(const NameValuePairs &source)
{
        DL_PrivateKey<T> *pPrivateKey = NULL;
        if (source.GetThisPointer(pPrivateKey))
                pPrivateKey->MakePublicKey(*this);
        else
        {
                this->AccessAbstractGroupParameters().AssignFrom(source);
                AssignFromHelper(this, source)
                        CRYPTOPP_SET_FUNCTION_ENTRY(PublicElement);
        }
}

class OID;

//! _
template <class PK, class GP, class O = OID>
class DL_KeyImpl : public PK
{
public:
        typedef GP GroupParameters;

#ifndef CRYPTOPP_MAINTAIN_BACKWARDS_COMPATIBILITY_562
        virtual ~DL_KeyImpl() { }
#endif

        O GetAlgorithmID() const {return GetGroupParameters().GetAlgorithmID();}
//      void BERDecode(BufferedTransformation &bt)
//              {PK::BERDecode(bt);}
//      void DEREncode(BufferedTransformation &bt) const
//              {PK::DEREncode(bt);}
        bool BERDecodeAlgorithmParameters(BufferedTransformation &bt)
                {AccessGroupParameters().BERDecode(bt); return true;}
        bool DEREncodeAlgorithmParameters(BufferedTransformation &bt) const
                {GetGroupParameters().DEREncode(bt); return true;}

        const GP & GetGroupParameters() const {return m_groupParameters;}
        GP & AccessGroupParameters() {return m_groupParameters;}

private:
        GP m_groupParameters;
};

class X509PublicKey;
class PKCS8PrivateKey;

//! _
template <class GP>
class DL_PrivateKeyImpl : public DL_PrivateKey<CPP_TYPENAME GP::Element>, public DL_KeyImpl<PKCS8PrivateKey, GP>
{
public:
        typedef typename GP::Element Element;

#ifndef CRYPTOPP_MAINTAIN_BACKWARDS_COMPATIBILITY_562
        virtual ~DL_PrivateKeyImpl() { }
#endif

        // GeneratableCryptoMaterial
        bool Validate(RandomNumberGenerator &rng, unsigned int level) const
        {
                bool pass = GetAbstractGroupParameters().Validate(rng, level);

                const Integer &q = GetAbstractGroupParameters().GetSubgroupOrder();
                const Integer &x = GetPrivateExponent();

                pass = pass && x.IsPositive() && x < q;
                if (level >= 1)
                        pass = pass && Integer::Gcd(x, q) == Integer::One();
                return pass;
        }

        bool GetVoidValue(const char *name, const std::type_info &valueType, void *pValue) const
        {
                return GetValueHelper<DL_PrivateKey<Element> >(this, name, valueType, pValue).Assignable();
        }

        void AssignFrom(const NameValuePairs &source)
        {
                AssignFromHelper<DL_PrivateKey<Element> >(this, source);
        }

        void GenerateRandom(RandomNumberGenerator &rng, const NameValuePairs &params)
        {
                if (!params.GetThisObject(this->AccessGroupParameters()))
                        this->AccessGroupParameters().GenerateRandom(rng, params);
//              std::pair<const byte *, int> seed;
                Integer x(rng, Integer::One(), GetAbstractGroupParameters().GetMaxExponent());
//                      Integer::ANY, Integer::Zero(), Integer::One(),
//                      params.GetValue("DeterministicKeyGenerationSeed", seed) ? &seed : NULL);
                SetPrivateExponent(x);
        }

        bool SupportsPrecomputation() const {return true;}

        void Precompute(unsigned int precomputationStorage=16)
                {AccessAbstractGroupParameters().Precompute(precomputationStorage);}

        void LoadPrecomputation(BufferedTransformation &storedPrecomputation)
                {AccessAbstractGroupParameters().LoadPrecomputation(storedPrecomputation);}

        void SavePrecomputation(BufferedTransformation &storedPrecomputation) const
                {GetAbstractGroupParameters().SavePrecomputation(storedPrecomputation);}

        // DL_Key
        const DL_GroupParameters<Element> & GetAbstractGroupParameters() const {return this->GetGroupParameters();}
        DL_GroupParameters<Element> & AccessAbstractGroupParameters() {return this->AccessGroupParameters();}

        // DL_PrivateKey
        const Integer & GetPrivateExponent() const {return m_x;}
        void SetPrivateExponent(const Integer &x) {m_x = x;}

        // PKCS8PrivateKey
        void BERDecodePrivateKey(BufferedTransformation &bt, bool, size_t)
                {m_x.BERDecode(bt);}
        void DEREncodePrivateKey(BufferedTransformation &bt) const
                {m_x.DEREncode(bt);}

private:
        Integer m_x;
};

//! _
template <class BASE, class SIGNATURE_SCHEME>
class DL_PrivateKey_WithSignaturePairwiseConsistencyTest : public BASE
{
public:
#ifndef CRYPTOPP_MAINTAIN_BACKWARDS_COMPATIBILITY_562
        virtual ~DL_PrivateKey_WithSignaturePairwiseConsistencyTest() { }
#endif

        void GenerateRandom(RandomNumberGenerator &rng, const NameValuePairs &params)
        {
                BASE::GenerateRandom(rng, params);

                if (FIPS_140_2_ComplianceEnabled())
                {
                        typename SIGNATURE_SCHEME::Signer signer(*this);
                        typename SIGNATURE_SCHEME::Verifier verifier(signer);
                        SignaturePairwiseConsistencyTest_FIPS_140_Only(signer, verifier);
                }
        }
};

//! _
template <class GP>
class DL_PublicKeyImpl : public DL_PublicKey<typename GP::Element>, public DL_KeyImpl<X509PublicKey, GP>
{
public:
        typedef typename GP::Element Element;

#ifndef CRYPTOPP_MAINTAIN_BACKWARDS_COMPATIBILITY_562
        virtual ~DL_PublicKeyImpl() { }
#endif

        // CryptoMaterial
        bool Validate(RandomNumberGenerator &rng, unsigned int level) const
        {
                bool pass = GetAbstractGroupParameters().Validate(rng, level);
                pass = pass && GetAbstractGroupParameters().ValidateElement(level, this->GetPublicElement(), &GetPublicPrecomputation());
                return pass;
        }

        bool GetVoidValue(const char *name, const std::type_info &valueType, void *pValue) const
        {
                return GetValueHelper<DL_PublicKey<Element> >(this, name, valueType, pValue).Assignable();
        }

        void AssignFrom(const NameValuePairs &source)
        {
                AssignFromHelper<DL_PublicKey<Element> >(this, source);
        }

        bool SupportsPrecomputation() const {return true;}

        void Precompute(unsigned int precomputationStorage=16)
        {
                AccessAbstractGroupParameters().Precompute(precomputationStorage);
                AccessPublicPrecomputation().Precompute(GetAbstractGroupParameters().GetGroupPrecomputation(), GetAbstractGroupParameters().GetSubgroupOrder().BitCount(), precomputationStorage);
        }

        void LoadPrecomputation(BufferedTransformation &storedPrecomputation)
        {
                AccessAbstractGroupParameters().LoadPrecomputation(storedPrecomputation);
                AccessPublicPrecomputation().Load(GetAbstractGroupParameters().GetGroupPrecomputation(), storedPrecomputation);
        }

        void SavePrecomputation(BufferedTransformation &storedPrecomputation) const
        {
                GetAbstractGroupParameters().SavePrecomputation(storedPrecomputation);
                GetPublicPrecomputation().Save(GetAbstractGroupParameters().GetGroupPrecomputation(), storedPrecomputation);
        }

        // DL_Key
        const DL_GroupParameters<Element> & GetAbstractGroupParameters() const {return this->GetGroupParameters();}
        DL_GroupParameters<Element> & AccessAbstractGroupParameters() {return this->AccessGroupParameters();}

        // DL_PublicKey
        const DL_FixedBasePrecomputation<Element> & GetPublicPrecomputation() const {return m_ypc;}
        DL_FixedBasePrecomputation<Element> & AccessPublicPrecomputation() {return m_ypc;}

        // non-inherited
        bool operator==(const DL_PublicKeyImpl<GP> &rhs) const
                {return this->GetGroupParameters() == rhs.GetGroupParameters() && this->GetPublicElement() == rhs.GetPublicElement();}

private:
        typename GP::BasePrecomputation m_ypc;
};

//! \brief Interface for Elgamal-like signature algorithms
template <class T>
class CRYPTOPP_NO_VTABLE DL_ElgamalLikeSignatureAlgorithm
{
public:
#ifndef CRYPTOPP_MAINTAIN_BACKWARDS_COMPATIBILITY_562
        virtual ~DL_ElgamalLikeSignatureAlgorithm() { }
#endif

        virtual void Sign(const DL_GroupParameters<T> &params, const Integer &privateKey, const Integer &k, const Integer &e, Integer &r, Integer &s) const =0;
        virtual bool Verify(const DL_GroupParameters<T> &params, const DL_PublicKey<T> &publicKey, const Integer &e, const Integer &r, const Integer &s) const =0;
        virtual Integer RecoverPresignature(const DL_GroupParameters<T> &params, const DL_PublicKey<T> &publicKey, const Integer &r, const Integer &s) const
        {
                CRYPTOPP_UNUSED(params); CRYPTOPP_UNUSED(publicKey); CRYPTOPP_UNUSED(r); CRYPTOPP_UNUSED(s);
                throw NotImplemented("DL_ElgamalLikeSignatureAlgorithm: this signature scheme does not support message recovery");
                MAYBE_RETURN(Integer::Zero());
        }
        virtual size_t RLen(const DL_GroupParameters<T> &params) const
                {return params.GetSubgroupOrder().ByteCount();}
        virtual size_t SLen(const DL_GroupParameters<T> &params) const
                {return params.GetSubgroupOrder().ByteCount();}
};

//! \brief Interface for DL key agreement algorithms
template <class T>
class CRYPTOPP_NO_VTABLE DL_KeyAgreementAlgorithm
{
public:
        typedef T Element;

#ifndef CRYPTOPP_MAINTAIN_BACKWARDS_COMPATIBILITY_562
        virtual ~DL_KeyAgreementAlgorithm() { }
#endif

        virtual Element AgreeWithEphemeralPrivateKey(const DL_GroupParameters<Element> &params, const DL_FixedBasePrecomputation<Element> &publicPrecomputation, const Integer &privateExponent) const =0;
        virtual Element AgreeWithStaticPrivateKey(const DL_GroupParameters<Element> &params, const Element &publicElement, bool validateOtherPublicKey, const Integer &privateExponent) const =0;
};

//! \brief Interface for key derivation algorithms used in DL cryptosystems
template <class T>
class CRYPTOPP_NO_VTABLE DL_KeyDerivationAlgorithm
{
public:
#ifndef CRYPTOPP_MAINTAIN_BACKWARDS_COMPATIBILITY_562
        virtual ~DL_KeyDerivationAlgorithm() { }
#endif

        virtual bool ParameterSupported(const char *name) const
                {CRYPTOPP_UNUSED(name); return false;}
        virtual void Derive(const DL_GroupParameters<T> &groupParams, byte *derivedKey, size_t derivedLength, const T &agreedElement, const T &ephemeralPublicKey, const NameValuePairs &derivationParams) const =0;
};

//! \brief Interface for symmetric encryption algorithms used in DL cryptosystems
class CRYPTOPP_NO_VTABLE DL_SymmetricEncryptionAlgorithm
{
public:
#ifndef CRYPTOPP_MAINTAIN_BACKWARDS_COMPATIBILITY_562
        virtual ~DL_SymmetricEncryptionAlgorithm() { }
#endif

        virtual bool ParameterSupported(const char *name) const
                {CRYPTOPP_UNUSED(name); return false;}
        virtual size_t GetSymmetricKeyLength(size_t plaintextLength) const =0;
        virtual size_t GetSymmetricCiphertextLength(size_t plaintextLength) const =0;
        virtual size_t GetMaxSymmetricPlaintextLength(size_t ciphertextLength) const =0;
        virtual void SymmetricEncrypt(RandomNumberGenerator &rng, const byte *key, const byte *plaintext, size_t plaintextLength, byte *ciphertext, const NameValuePairs &parameters) const =0;
        virtual DecodingResult SymmetricDecrypt(const byte *key, const byte *ciphertext, size_t ciphertextLength, byte *plaintext, const NameValuePairs &parameters) const =0;
};

//! \brief Discrete Log (DL) base interface
//! \tparam KI public or private key interface
template <class KI>
class CRYPTOPP_NO_VTABLE DL_Base
{
protected:
        typedef KI KeyInterface;
        typedef typename KI::Element Element;

#ifndef CRYPTOPP_MAINTAIN_BACKWARDS_COMPATIBILITY_562
        virtual ~DL_Base() { }
#endif

        const DL_GroupParameters<Element> & GetAbstractGroupParameters() const {return GetKeyInterface().GetAbstractGroupParameters();}
        DL_GroupParameters<Element> & AccessAbstractGroupParameters() {return AccessKeyInterface().AccessAbstractGroupParameters();}

        virtual KeyInterface & AccessKeyInterface() =0;
        virtual const KeyInterface & GetKeyInterface() const =0;
};

//! \brief Discrete Log (DL) signature scheme base implementation
//! \tparam INTERFACE PK_Signer or PK_Verifier derived class
//! \tparam DL_Base key base used in the scheme
//! \details DL_SignatureSchemeBase provides common functions for signers and verifiers.
//!   DL_Base<DL_PrivateKey> is used for signers, and DL_Base<DL_PublicKey> is used for verifiers.
template <class INTERFACE, class KEY_INTERFACE>
class CRYPTOPP_NO_VTABLE DL_SignatureSchemeBase : public INTERFACE, public DL_Base<KEY_INTERFACE>
{
public:
#ifndef CRYPTOPP_MAINTAIN_BACKWARDS_COMPATIBILITY_562
        virtual ~DL_SignatureSchemeBase() { }
#endif

        //! \brief Provides the signature length
        //! \returns signature length, in bytes
        //! \details SignatureLength returns the size required for <tt>r+s</tt>.
        size_t SignatureLength() const
        {
                return GetSignatureAlgorithm().RLen(this->GetAbstractGroupParameters())
                        + GetSignatureAlgorithm().SLen(this->GetAbstractGroupParameters());
        }

        //! \brief Provides the maximum recoverable length
        //! \returns maximum recoverable length, in bytes
        size_t MaxRecoverableLength() const
                {return GetMessageEncodingInterface().MaxRecoverableLength(0, GetHashIdentifier().second, GetDigestSize());}

        //! \brief Provides the maximum recoverable length
        //! \param signatureLength the size fo the signature
        //! \returns maximum recoverable length based on signature length, in bytes
        //! \details this function is not implemented and always returns 0.
        size_t MaxRecoverableLengthFromSignatureLength(size_t signatureLength) const
                {CRYPTOPP_UNUSED(signatureLength); CRYPTOPP_ASSERT(false); return 0;}   // TODO

        //! \brief Determines if the scheme is probabilistic
        //! \returns true if the scheme is probabilistic, false otherwise
        bool IsProbabilistic() const
                {return true;}

        //! \brief Determines if the scheme has non-recoverable part
        //! \returns true if the message encoding has a non-recoverable part, false otherwise.
        bool AllowNonrecoverablePart() const
                {return GetMessageEncodingInterface().AllowNonrecoverablePart();}

        //! \brief Determines if the scheme allows recoverable part first
        //! \returns true if the message encoding allows the recoverable part, false otherwise.
        bool RecoverablePartFirst() const
                {return GetMessageEncodingInterface().RecoverablePartFirst();}

protected:
        size_t MessageRepresentativeLength() const {return BitsToBytes(MessageRepresentativeBitLength());}
        size_t MessageRepresentativeBitLength() const {return this->GetAbstractGroupParameters().GetSubgroupOrder().BitCount();}

        virtual const DL_ElgamalLikeSignatureAlgorithm<CPP_TYPENAME KEY_INTERFACE::Element> & GetSignatureAlgorithm() const =0;
        virtual const PK_SignatureMessageEncodingMethod & GetMessageEncodingInterface() const =0;
        virtual HashIdentifier GetHashIdentifier() const =0;
        virtual size_t GetDigestSize() const =0;
};

//! \brief Discrete Log (DL) signature scheme signer base implementation
//! \tparam T
template <class T>
class CRYPTOPP_NO_VTABLE DL_SignerBase : public DL_SignatureSchemeBase<PK_Signer, DL_PrivateKey<T> >
{
public:
#ifndef CRYPTOPP_MAINTAIN_BACKWARDS_COMPATIBILITY_562
        virtual ~DL_SignerBase() { }
#endif

        //! \brief Testing interface
        //! \param k Integer
        //! \param e Integer
        //! \param r Integer
        //! \param s Integer
        void RawSign(const Integer &k, const Integer &e, Integer &r, Integer &s) const
        {
                const DL_ElgamalLikeSignatureAlgorithm<T> &alg = this->GetSignatureAlgorithm();
                const DL_GroupParameters<T> &params = this->GetAbstractGroupParameters();
                const DL_PrivateKey<T> &key = this->GetKeyInterface();

                r = params.ConvertElementToInteger(params.ExponentiateBase(k));
                alg.Sign(params, key.GetPrivateExponent(), k, e, r, s);
        }

        void InputRecoverableMessage(PK_MessageAccumulator &messageAccumulator, const byte *recoverableMessage, size_t recoverableMessageLength) const
        {
                PK_MessageAccumulatorBase &ma = static_cast<PK_MessageAccumulatorBase &>(messageAccumulator);
                ma.m_recoverableMessage.Assign(recoverableMessage, recoverableMessageLength);
                this->GetMessageEncodingInterface().ProcessRecoverableMessage(ma.AccessHash(),
                        recoverableMessage, recoverableMessageLength,
                        ma.m_presignature, ma.m_presignature.size(),
                        ma.m_semisignature);
        }

        size_t SignAndRestart(RandomNumberGenerator &rng, PK_MessageAccumulator &messageAccumulator, byte *signature, bool restart) const
        {
                this->GetMaterial().DoQuickSanityCheck();

                PK_MessageAccumulatorBase &ma = static_cast<PK_MessageAccumulatorBase &>(messageAccumulator);
                const DL_ElgamalLikeSignatureAlgorithm<T> &alg = this->GetSignatureAlgorithm();
                const DL_GroupParameters<T> &params = this->GetAbstractGroupParameters();
                const DL_PrivateKey<T> &key = this->GetKeyInterface();

                SecByteBlock representative(this->MessageRepresentativeLength());
                this->GetMessageEncodingInterface().ComputeMessageRepresentative(
                        rng,
                        ma.m_recoverableMessage, ma.m_recoverableMessage.size(),
                        ma.AccessHash(), this->GetHashIdentifier(), ma.m_empty,
                        representative, this->MessageRepresentativeBitLength());
                ma.m_empty = true;
                Integer e(representative, representative.size());

                // hash message digest into random number k to prevent reusing the same k on a different messages
                // after virtual machine rollback
                if (rng.CanIncorporateEntropy())
                        rng.IncorporateEntropy(representative, representative.size());
                Integer k(rng, 1, params.GetSubgroupOrder()-1);
                Integer r, s;
                r = params.ConvertElementToInteger(params.ExponentiateBase(k));
                alg.Sign(params, key.GetPrivateExponent(), k, e, r, s);

                /*
                Integer r, s;
                if (this->MaxRecoverableLength() > 0)
                        r.Decode(ma.m_semisignature, ma.m_semisignature.size());
                else
                        r.Decode(ma.m_presignature, ma.m_presignature.size());
                alg.Sign(params, key.GetPrivateExponent(), ma.m_k, e, r, s);
                */

                size_t rLen = alg.RLen(params);
                r.Encode(signature, rLen);
                s.Encode(signature+rLen, alg.SLen(params));

                if (restart)
                        RestartMessageAccumulator(rng, ma);

                return this->SignatureLength();
        }

protected:
        void RestartMessageAccumulator(RandomNumberGenerator &rng, PK_MessageAccumulatorBase &ma) const
        {
                // k needs to be generated before hashing for signature schemes with recovery
                // but to defend against VM rollbacks we need to generate k after hashing.
                // so this code is commented out, since no DL-based signature scheme with recovery
                // has been implemented in Crypto++ anyway
                /*
                const DL_ElgamalLikeSignatureAlgorithm<T> &alg = this->GetSignatureAlgorithm();
                const DL_GroupParameters<T> &params = this->GetAbstractGroupParameters();
                ma.m_k.Randomize(rng, 1, params.GetSubgroupOrder()-1);
                ma.m_presignature.New(params.GetEncodedElementSize(false));
                params.ConvertElementToInteger(params.ExponentiateBase(ma.m_k)).Encode(ma.m_presignature, ma.m_presignature.size());
                */
                CRYPTOPP_UNUSED(rng); CRYPTOPP_UNUSED(ma);
        }
};

//! _
template <class T>
class CRYPTOPP_NO_VTABLE DL_VerifierBase : public DL_SignatureSchemeBase<PK_Verifier, DL_PublicKey<T> >
{
public:
#ifndef CRYPTOPP_MAINTAIN_BACKWARDS_COMPATIBILITY_562
        virtual ~DL_VerifierBase() { }
#endif

        void InputSignature(PK_MessageAccumulator &messageAccumulator, const byte *signature, size_t signatureLength) const
        {
                CRYPTOPP_UNUSED(signature); CRYPTOPP_UNUSED(signatureLength);
                PK_MessageAccumulatorBase &ma = static_cast<PK_MessageAccumulatorBase &>(messageAccumulator);
                const DL_ElgamalLikeSignatureAlgorithm<T> &alg = this->GetSignatureAlgorithm();
                const DL_GroupParameters<T> &params = this->GetAbstractGroupParameters();

                size_t rLen = alg.RLen(params);
                ma.m_semisignature.Assign(signature, rLen);
                ma.m_s.Decode(signature+rLen, alg.SLen(params));

                this->GetMessageEncodingInterface().ProcessSemisignature(ma.AccessHash(), ma.m_semisignature, ma.m_semisignature.size());
        }

        bool VerifyAndRestart(PK_MessageAccumulator &messageAccumulator) const
        {
                this->GetMaterial().DoQuickSanityCheck();

                PK_MessageAccumulatorBase &ma = static_cast<PK_MessageAccumulatorBase &>(messageAccumulator);
                const DL_ElgamalLikeSignatureAlgorithm<T> &alg = this->GetSignatureAlgorithm();
                const DL_GroupParameters<T> &params = this->GetAbstractGroupParameters();
                const DL_PublicKey<T> &key = this->GetKeyInterface();

                SecByteBlock representative(this->MessageRepresentativeLength());
                this->GetMessageEncodingInterface().ComputeMessageRepresentative(NullRNG(), ma.m_recoverableMessage, ma.m_recoverableMessage.size(),
                        ma.AccessHash(), this->GetHashIdentifier(), ma.m_empty,
                        representative, this->MessageRepresentativeBitLength());
                ma.m_empty = true;
                Integer e(representative, representative.size());

                Integer r(ma.m_semisignature, ma.m_semisignature.size());
                return alg.Verify(params, key, e, r, ma.m_s);
        }

        DecodingResult RecoverAndRestart(byte *recoveredMessage, PK_MessageAccumulator &messageAccumulator) const
        {
                this->GetMaterial().DoQuickSanityCheck();

                PK_MessageAccumulatorBase &ma = static_cast<PK_MessageAccumulatorBase &>(messageAccumulator);
                const DL_ElgamalLikeSignatureAlgorithm<T> &alg = this->GetSignatureAlgorithm();
                const DL_GroupParameters<T> &params = this->GetAbstractGroupParameters();
                const DL_PublicKey<T> &key = this->GetKeyInterface();

                SecByteBlock representative(this->MessageRepresentativeLength());
                this->GetMessageEncodingInterface().ComputeMessageRepresentative(
                        NullRNG(),
                        ma.m_recoverableMessage, ma.m_recoverableMessage.size(),
                        ma.AccessHash(), this->GetHashIdentifier(), ma.m_empty,
                        representative, this->MessageRepresentativeBitLength());
                ma.m_empty = true;
                Integer e(representative, representative.size());

                ma.m_presignature.New(params.GetEncodedElementSize(false));
                Integer r(ma.m_semisignature, ma.m_semisignature.size());
                alg.RecoverPresignature(params, key, r, ma.m_s).Encode(ma.m_presignature, ma.m_presignature.size());

                return this->GetMessageEncodingInterface().RecoverMessageFromSemisignature(
                        ma.AccessHash(), this->GetHashIdentifier(),
                        ma.m_presignature, ma.m_presignature.size(),
                        ma.m_semisignature, ma.m_semisignature.size(),
                        recoveredMessage);
        }
};

//! \brief Discrete Log (DL) cryptosystem base implementation
//! \tparam PK field element type
//! \tparam KI public or private key interface
template <class PK, class KI>
class CRYPTOPP_NO_VTABLE DL_CryptoSystemBase : public PK, public DL_Base<KI>
{
public:
        typedef typename DL_Base<KI>::Element Element;

#ifndef CRYPTOPP_MAINTAIN_BACKWARDS_COMPATIBILITY_562
        virtual ~DL_CryptoSystemBase() { }
#endif

        size_t MaxPlaintextLength(size_t ciphertextLength) const
        {
                unsigned int minLen = this->GetAbstractGroupParameters().GetEncodedElementSize(true);
                return ciphertextLength < minLen ? 0 : GetSymmetricEncryptionAlgorithm().GetMaxSymmetricPlaintextLength(ciphertextLength - minLen);
        }

        size_t CiphertextLength(size_t plaintextLength) const
        {
                size_t len = GetSymmetricEncryptionAlgorithm().GetSymmetricCiphertextLength(plaintextLength);
                return len == 0 ? 0 : this->GetAbstractGroupParameters().GetEncodedElementSize(true) + len;
        }

        bool ParameterSupported(const char *name) const
                {return GetKeyDerivationAlgorithm().ParameterSupported(name) || GetSymmetricEncryptionAlgorithm().ParameterSupported(name);}

protected:
        virtual const DL_KeyAgreementAlgorithm<Element> & GetKeyAgreementAlgorithm() const =0;
        virtual const DL_KeyDerivationAlgorithm<Element> & GetKeyDerivationAlgorithm() const =0;
        virtual const DL_SymmetricEncryptionAlgorithm & GetSymmetricEncryptionAlgorithm() const =0;
};

//! \brief Discrete Log (DL) decryptor base implementation
//! \tparam T field element type
template <class T>
class CRYPTOPP_NO_VTABLE DL_DecryptorBase : public DL_CryptoSystemBase<PK_Decryptor, DL_PrivateKey<T> >
{
public:
        typedef T Element;

#ifndef CRYPTOPP_MAINTAIN_BACKWARDS_COMPATIBILITY_562
        virtual ~DL_DecryptorBase() { }
#endif

        DecodingResult Decrypt(RandomNumberGenerator &rng, const byte *ciphertext, size_t ciphertextLength, byte *plaintext, const NameValuePairs &parameters = g_nullNameValuePairs) const
        {
                try
                {
                        CRYPTOPP_UNUSED(rng);
                        const DL_KeyAgreementAlgorithm<T> &agreeAlg = this->GetKeyAgreementAlgorithm();
                        const DL_KeyDerivationAlgorithm<T> &derivAlg = this->GetKeyDerivationAlgorithm();
                        const DL_SymmetricEncryptionAlgorithm &encAlg = this->GetSymmetricEncryptionAlgorithm();
                        const DL_GroupParameters<T> &params = this->GetAbstractGroupParameters();
                        const DL_PrivateKey<T> &key = this->GetKeyInterface();

                        Element q = params.DecodeElement(ciphertext, true);
                        size_t elementSize = params.GetEncodedElementSize(true);
                        ciphertext += elementSize;
                        ciphertextLength -= elementSize;

                        Element z = agreeAlg.AgreeWithStaticPrivateKey(params, q, true, key.GetPrivateExponent());

                        SecByteBlock derivedKey(encAlg.GetSymmetricKeyLength(encAlg.GetMaxSymmetricPlaintextLength(ciphertextLength)));
                        derivAlg.Derive(params, derivedKey, derivedKey.size(), z, q, parameters);

                        return encAlg.SymmetricDecrypt(derivedKey, ciphertext, ciphertextLength, plaintext, parameters);
                }
                catch (DL_BadElement &)
                {
                        return DecodingResult();
                }
        }
};

//! \brief Discrete Log (DL) encryptor base implementation
//! \tparam T field element type
template <class T>
class CRYPTOPP_NO_VTABLE DL_EncryptorBase : public DL_CryptoSystemBase<PK_Encryptor, DL_PublicKey<T> >
{
public:
        typedef T Element;

#ifndef CRYPTOPP_MAINTAIN_BACKWARDS_COMPATIBILITY_562
        virtual ~DL_EncryptorBase() { }
#endif

        void Encrypt(RandomNumberGenerator &rng, const byte *plaintext, size_t plaintextLength, byte *ciphertext, const NameValuePairs &parameters = g_nullNameValuePairs) const
        {
                const DL_KeyAgreementAlgorithm<T> &agreeAlg = this->GetKeyAgreementAlgorithm();
                const DL_KeyDerivationAlgorithm<T> &derivAlg = this->GetKeyDerivationAlgorithm();
                const DL_SymmetricEncryptionAlgorithm &encAlg = this->GetSymmetricEncryptionAlgorithm();
                const DL_GroupParameters<T> &params = this->GetAbstractGroupParameters();
                const DL_PublicKey<T> &key = this->GetKeyInterface();

                Integer x(rng, Integer::One(), params.GetMaxExponent());
                Element q = params.ExponentiateBase(x);
                params.EncodeElement(true, q, ciphertext);
                unsigned int elementSize = params.GetEncodedElementSize(true);
                ciphertext += elementSize;

                Element z = agreeAlg.AgreeWithEphemeralPrivateKey(params, key.GetPublicPrecomputation(), x);

                SecByteBlock derivedKey(encAlg.GetSymmetricKeyLength(plaintextLength));
                derivAlg.Derive(params, derivedKey, derivedKey.size(), z, q, parameters);

                encAlg.SymmetricEncrypt(rng, derivedKey, plaintext, plaintextLength, ciphertext, parameters);
        }
};

//! \brief Discrete Log (DL) scheme options
//! \tparam T1 algorithm information
//! \tparam T2 group paramters for the scheme
template <class T1, class T2>
struct DL_SchemeOptionsBase
{
        typedef T1 AlgorithmInfo;
        typedef T2 GroupParameters;
        typedef typename GroupParameters::Element Element;
};

//! \brief Discrete Log (DL) key options
//! \tparam T1 algorithm information
//! \tparam T2 keys used in the scheme
template <class T1, class T2>
struct DL_KeyedSchemeOptions : public DL_SchemeOptionsBase<T1, typename T2::PublicKey::GroupParameters>
{
        typedef T2 Keys;
        typedef typename Keys::PrivateKey PrivateKey;
        typedef typename Keys::PublicKey PublicKey;
};

//! \brief Discrete Log (DL) signature scheme options
//! \tparam T1 algorithm information
//! \tparam T2 keys used in the scheme
//! \tparam T3 signature algorithm
//! \tparam T4 message encoding method
//! \tparam T5 hash function
template <class T1, class T2, class T3, class T4, class T5>
struct DL_SignatureSchemeOptions : public DL_KeyedSchemeOptions<T1, T2>
{
        typedef T3 SignatureAlgorithm;
        typedef T4 MessageEncodingMethod;
        typedef T5 HashFunction;
};

//! \brief Discrete Log (DL) crypto scheme options
//! \tparam T1 algorithm information
//! \tparam T2 keys used in the scheme
//! \tparam T3 key agreement algorithm
//! \tparam T4 key derivation algorithm
//! \tparam T5 symmetric encryption algorithm
template <class T1, class T2, class T3, class T4, class T5>
struct DL_CryptoSchemeOptions : public DL_KeyedSchemeOptions<T1, T2>
{
        typedef T3 KeyAgreementAlgorithm;
        typedef T4 KeyDerivationAlgorithm;
        typedef T5 SymmetricEncryptionAlgorithm;
};

//! \brief Discrete Log (DL) base object implementation
//! \tparam BASE TODO
//! \tparam SCHEME_OPTIONS options for the scheme
//! \tparam KEY key used in the scheme
template <class BASE, class SCHEME_OPTIONS, class KEY>
class CRYPTOPP_NO_VTABLE DL_ObjectImplBase : public AlgorithmImpl<BASE, typename SCHEME_OPTIONS::AlgorithmInfo>
{
public:
        typedef SCHEME_OPTIONS SchemeOptions;
        typedef typename KEY::Element Element;

#ifndef CRYPTOPP_MAINTAIN_BACKWARDS_COMPATIBILITY_562
        virtual ~DL_ObjectImplBase() { }
#endif

        PrivateKey & AccessPrivateKey() {return m_key;}
        PublicKey & AccessPublicKey() {return m_key;}

        // KeyAccessor
        const KEY & GetKey() const {return m_key;}
        KEY & AccessKey() {return m_key;}

protected:
        typename BASE::KeyInterface & AccessKeyInterface() {return m_key;}
        const typename BASE::KeyInterface & GetKeyInterface() const {return m_key;}

        // for signature scheme
        HashIdentifier GetHashIdentifier() const
        {
                typedef typename SchemeOptions::MessageEncodingMethod::HashIdentifierLookup HashLookup;
                return HashLookup::template HashIdentifierLookup2<CPP_TYPENAME SchemeOptions::HashFunction>::Lookup();
        }
        size_t GetDigestSize() const
        {
                typedef CPP_TYPENAME SchemeOptions::HashFunction H;
                return H::DIGESTSIZE;
        }

private:
        KEY m_key;
};

//! \brief Discrete Log (DL) object implementation
//! \tparam BASE TODO
//! \tparam SCHEME_OPTIONS options for the scheme
//! \tparam KEY key used in the scheme
template <class BASE, class SCHEME_OPTIONS, class KEY>
class CRYPTOPP_NO_VTABLE DL_ObjectImpl : public DL_ObjectImplBase<BASE, SCHEME_OPTIONS, KEY>
{
public:
        typedef typename KEY::Element Element;

#ifndef CRYPTOPP_MAINTAIN_BACKWARDS_COMPATIBILITY_562
        virtual ~DL_ObjectImpl() { }
#endif

protected:
        const DL_ElgamalLikeSignatureAlgorithm<Element> & GetSignatureAlgorithm() const
                {return Singleton<CPP_TYPENAME SCHEME_OPTIONS::SignatureAlgorithm>().Ref();}
        const DL_KeyAgreementAlgorithm<Element> & GetKeyAgreementAlgorithm() const
                {return Singleton<CPP_TYPENAME SCHEME_OPTIONS::KeyAgreementAlgorithm>().Ref();}
        const DL_KeyDerivationAlgorithm<Element> & GetKeyDerivationAlgorithm() const
                {return Singleton<CPP_TYPENAME SCHEME_OPTIONS::KeyDerivationAlgorithm>().Ref();}
        const DL_SymmetricEncryptionAlgorithm & GetSymmetricEncryptionAlgorithm() const
                {return Singleton<CPP_TYPENAME SCHEME_OPTIONS::SymmetricEncryptionAlgorithm>().Ref();}
        HashIdentifier GetHashIdentifier() const
                {return HashIdentifier();}
        const PK_SignatureMessageEncodingMethod & GetMessageEncodingInterface() const
                {return Singleton<CPP_TYPENAME SCHEME_OPTIONS::MessageEncodingMethod>().Ref();}
};

//! \brief Discrete Log (DL) signer implementation
//! \tparam SCHEME_OPTIONS options for the scheme
template <class SCHEME_OPTIONS>
class DL_SignerImpl : public DL_ObjectImpl<DL_SignerBase<typename SCHEME_OPTIONS::Element>, SCHEME_OPTIONS, typename SCHEME_OPTIONS::PrivateKey>
{
public:
        PK_MessageAccumulator * NewSignatureAccumulator(RandomNumberGenerator &rng) const
        {
                member_ptr<PK_MessageAccumulatorBase> p(new PK_MessageAccumulatorImpl<CPP_TYPENAME SCHEME_OPTIONS::HashFunction>);
                this->RestartMessageAccumulator(rng, *p);
                return p.release();
        }
};

//! \brief Discrete Log (DL) verifier implementation
//! \tparam SCHEME_OPTIONS options for the scheme
template <class SCHEME_OPTIONS>
class DL_VerifierImpl : public DL_ObjectImpl<DL_VerifierBase<typename SCHEME_OPTIONS::Element>, SCHEME_OPTIONS, typename SCHEME_OPTIONS::PublicKey>
{
public:
        PK_MessageAccumulator * NewVerificationAccumulator() const
        {
                return new PK_MessageAccumulatorImpl<CPP_TYPENAME SCHEME_OPTIONS::HashFunction>;
        }
};

//! \brief Discrete Log (DL) encryptor implementation
//! \tparam SCHEME_OPTIONS options for the scheme
template <class SCHEME_OPTIONS>
class DL_EncryptorImpl : public DL_ObjectImpl<DL_EncryptorBase<typename SCHEME_OPTIONS::Element>, SCHEME_OPTIONS, typename SCHEME_OPTIONS::PublicKey>
{
};

//! \brief Discrete Log (DL) decryptor implementation
//! \tparam SCHEME_OPTIONS options for the scheme
template <class SCHEME_OPTIONS>
class DL_DecryptorImpl : public DL_ObjectImpl<DL_DecryptorBase<typename SCHEME_OPTIONS::Element>, SCHEME_OPTIONS, typename SCHEME_OPTIONS::PrivateKey>
{
};

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

//! \brief Discrete Log (DL) simple key agreement base implementation
//! \tparam T class or type
template <class T>
class CRYPTOPP_NO_VTABLE DL_SimpleKeyAgreementDomainBase : public SimpleKeyAgreementDomain
{
public:
        typedef T Element;

#ifndef CRYPTOPP_MAINTAIN_BACKWARDS_COMPATIBILITY_562
        virtual ~DL_SimpleKeyAgreementDomainBase() { }
#endif

        CryptoParameters & AccessCryptoParameters() {return AccessAbstractGroupParameters();}
        unsigned int AgreedValueLength() const {return GetAbstractGroupParameters().GetEncodedElementSize(false);}
        unsigned int PrivateKeyLength() const {return GetAbstractGroupParameters().GetSubgroupOrder().ByteCount();}
        unsigned int PublicKeyLength() const {return GetAbstractGroupParameters().GetEncodedElementSize(true);}

        void GeneratePrivateKey(RandomNumberGenerator &rng, byte *privateKey) const
        {
                Integer x(rng, Integer::One(), GetAbstractGroupParameters().GetMaxExponent());
                x.Encode(privateKey, PrivateKeyLength());
        }

        void GeneratePublicKey(RandomNumberGenerator &rng, const byte *privateKey, byte *publicKey) const
        {
                CRYPTOPP_UNUSED(rng);
                const DL_GroupParameters<T> &params = GetAbstractGroupParameters();
                Integer x(privateKey, PrivateKeyLength());
                Element y = params.ExponentiateBase(x);
                params.EncodeElement(true, y, publicKey);
        }

        bool Agree(byte *agreedValue, const byte *privateKey, const byte *otherPublicKey, bool validateOtherPublicKey=true) const
        {
                try
                {
                        const DL_GroupParameters<T> &params = GetAbstractGroupParameters();
                        Integer x(privateKey, PrivateKeyLength());
                        Element w = params.DecodeElement(otherPublicKey, validateOtherPublicKey);

                        Element z = GetKeyAgreementAlgorithm().AgreeWithStaticPrivateKey(
                                GetAbstractGroupParameters(), w, validateOtherPublicKey, x);
                        params.EncodeElement(false, z, agreedValue);
                }
                catch (DL_BadElement &)
                {
                        return false;
                }
                return true;
        }

        //! \brief Retrieves a reference to the group generator
        //! \returns const reference to the group generator
        const Element &GetGenerator() const {return GetAbstractGroupParameters().GetSubgroupGenerator();}

protected:
        virtual const DL_KeyAgreementAlgorithm<Element> & GetKeyAgreementAlgorithm() const =0;
        virtual DL_GroupParameters<Element> & AccessAbstractGroupParameters() =0;
        const DL_GroupParameters<Element> & GetAbstractGroupParameters() const {return const_cast<DL_SimpleKeyAgreementDomainBase<Element> *>(this)->AccessAbstractGroupParameters();}
};

//! \brief Methods for avoiding "Small-Subgroup" attacks on Diffie-Hellman Key Agreement
//! \details Additional methods exist and include public key validation and choice of prime p.
//! \sa <A HREF="http://tools.ietf.org/html/rfc2785">Methods for Avoiding the "Small-Subgroup" Attacks on the
//!   Diffie-Hellman Key Agreement Method for S/MIME</A>
enum CofactorMultiplicationOption {
        //! \brief No cofactor multiplication applied
        NO_COFACTOR_MULTIPLICTION,
        //! \brief Cofactor multiplication compatible with ordinary Diffie-Hellman
        //! \details Modifies the computation of ZZ by including j (the cofactor) in the computations and is
        //!   compatible with ordinary Diffie-Hellman.
        COMPATIBLE_COFACTOR_MULTIPLICTION,
        //! \brief Cofactor multiplication incompatible with ordinary Diffie-Hellman
        //! \details Modifies the computation of ZZ by including j (the cofactor) in the computations but is
        //!   not compatible with ordinary Diffie-Hellman.
        INCOMPATIBLE_COFACTOR_MULTIPLICTION};

typedef EnumToType<CofactorMultiplicationOption, NO_COFACTOR_MULTIPLICTION> NoCofactorMultiplication;
typedef EnumToType<CofactorMultiplicationOption, COMPATIBLE_COFACTOR_MULTIPLICTION> CompatibleCofactorMultiplication;
typedef EnumToType<CofactorMultiplicationOption, INCOMPATIBLE_COFACTOR_MULTIPLICTION> IncompatibleCofactorMultiplication;

//! \details Diffie-Hellman key agreement algorithm
template <class ELEMENT, class COFACTOR_OPTION>
class DL_KeyAgreementAlgorithm_DH : public DL_KeyAgreementAlgorithm<ELEMENT>
{
public:
        typedef ELEMENT Element;

#ifndef CRYPTOPP_MAINTAIN_BACKWARDS_COMPATIBILITY_562
        virtual ~DL_KeyAgreementAlgorithm_DH() {}
#endif

        CRYPTOPP_CONSTEXPR static const char * CRYPTOPP_API StaticAlgorithmName()
                {return COFACTOR_OPTION::ToEnum() == INCOMPATIBLE_COFACTOR_MULTIPLICTION ? "DHC" : "DH";}

        Element AgreeWithEphemeralPrivateKey(const DL_GroupParameters<Element> &params, const DL_FixedBasePrecomputation<Element> &publicPrecomputation, const Integer &privateExponent) const
        {
                return publicPrecomputation.Exponentiate(params.GetGroupPrecomputation(),
                        COFACTOR_OPTION::ToEnum() == INCOMPATIBLE_COFACTOR_MULTIPLICTION ? privateExponent*params.GetCofactor() : privateExponent);
        }

        Element AgreeWithStaticPrivateKey(const DL_GroupParameters<Element> &params, const Element &publicElement, bool validateOtherPublicKey, const Integer &privateExponent) const
        {
                if (COFACTOR_OPTION::ToEnum() == COMPATIBLE_COFACTOR_MULTIPLICTION)
                {
                        const Integer &k = params.GetCofactor();
                        return params.ExponentiateElement(publicElement,
                                ModularArithmetic(params.GetSubgroupOrder()).Divide(privateExponent, k)*k);
                }
                else if (COFACTOR_OPTION::ToEnum() == INCOMPATIBLE_COFACTOR_MULTIPLICTION)
                        return params.ExponentiateElement(publicElement, privateExponent*params.GetCofactor());
                else
                {
                        CRYPTOPP_ASSERT(COFACTOR_OPTION::ToEnum() == NO_COFACTOR_MULTIPLICTION);

                        if (!validateOtherPublicKey)
                                return params.ExponentiateElement(publicElement, privateExponent);

                        if (params.FastSubgroupCheckAvailable())
                        {
                                if (!params.ValidateElement(2, publicElement, NULL))
                                        throw DL_BadElement();
                                return params.ExponentiateElement(publicElement, privateExponent);
                        }
                        else
                        {
                                const Integer e[2] = {params.GetSubgroupOrder(), privateExponent};
                                Element r[2];
                                params.SimultaneousExponentiate(r, publicElement, e, 2);
                                if (!params.IsIdentity(r[0]))
                                        throw DL_BadElement();
                                return r[1];
                        }
                }
        }
};

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

//! \brief Template implementing constructors for public key algorithm classes
template <class BASE>
class CRYPTOPP_NO_VTABLE PK_FinalTemplate : public BASE
{
public:
        PK_FinalTemplate() {}

        PK_FinalTemplate(const CryptoMaterial &key)
                {this->AccessKey().AssignFrom(key);}

        PK_FinalTemplate(BufferedTransformation &bt)
                {this->AccessKey().BERDecode(bt);}

        PK_FinalTemplate(const AsymmetricAlgorithm &algorithm)
                {this->AccessKey().AssignFrom(algorithm.GetMaterial());}

        PK_FinalTemplate(const Integer &v1)
                {this->AccessKey().Initialize(v1);}

#if (defined(_MSC_VER) && _MSC_VER < 1300)

        template <class T1, class T2>
        PK_FinalTemplate(T1 &v1, T2 &v2)
                {this->AccessKey().Initialize(v1, v2);}

        template <class T1, class T2, class T3>
        PK_FinalTemplate(T1 &v1, T2 &v2, T3 &v3)
                {this->AccessKey().Initialize(v1, v2, v3);}

        template <class T1, class T2, class T3, class T4>
        PK_FinalTemplate(T1 &v1, T2 &v2, T3 &v3, T4 &v4)
                {this->AccessKey().Initialize(v1, v2, v3, v4);}

        template <class T1, class T2, class T3, class T4, class T5>
        PK_FinalTemplate(T1 &v1, T2 &v2, T3 &v3, T4 &v4, T5 &v5)
                {this->AccessKey().Initialize(v1, v2, v3, v4, v5);}

        template <class T1, class T2, class T3, class T4, class T5, class T6>
        PK_FinalTemplate(T1 &v1, T2 &v2, T3 &v3, T4 &v4, T5 &v5, T6 &v6)
                {this->AccessKey().Initialize(v1, v2, v3, v4, v5, v6);}

        template <class T1, class T2, class T3, class T4, class T5, class T6, class T7>
        PK_FinalTemplate(T1 &v1, T2 &v2, T3 &v3, T4 &v4, T5 &v5, T6 &v6, T7 &v7)
                {this->AccessKey().Initialize(v1, v2, v3, v4, v5, v6, v7);}

        template <class T1, class T2, class T3, class T4, class T5, class T6, class T7, class T8>
        PK_FinalTemplate(T1 &v1, T2 &v2, T3 &v3, T4 &v4, T5 &v5, T6 &v6, T7 &v7, T8 &v8)
                {this->AccessKey().Initialize(v1, v2, v3, v4, v5, v6, v7, v8);}

#else

        template <class T1, class T2>
        PK_FinalTemplate(const T1 &v1, const T2 &v2)
                {this->AccessKey().Initialize(v1, v2);}

        template <class T1, class T2, class T3>
        PK_FinalTemplate(const T1 &v1, const T2 &v2, const T3 &v3)
                {this->AccessKey().Initialize(v1, v2, v3);}

        template <class T1, class T2, class T3, class T4>
        PK_FinalTemplate(const T1 &v1, const T2 &v2, const T3 &v3, const T4 &v4)
                {this->AccessKey().Initialize(v1, v2, v3, v4);}

        template <class T1, class T2, class T3, class T4, class T5>
        PK_FinalTemplate(const T1 &v1, const T2 &v2, const T3 &v3, const T4 &v4, const T5 &v5)
                {this->AccessKey().Initialize(v1, v2, v3, v4, v5);}

        template <class T1, class T2, class T3, class T4, class T5, class T6>
        PK_FinalTemplate(const T1 &v1, const T2 &v2, const T3 &v3, const T4 &v4, const T5 &v5, const T6 &v6)
                {this->AccessKey().Initialize(v1, v2, v3, v4, v5, v6);}

        template <class T1, class T2, class T3, class T4, class T5, class T6, class T7>
        PK_FinalTemplate(const T1 &v1, const T2 &v2, const T3 &v3, const T4 &v4, const T5 &v5, const T6 &v6, const T7 &v7)
                {this->AccessKey().Initialize(v1, v2, v3, v4, v5, v6, v7);}

        template <class T1, class T2, class T3, class T4, class T5, class T6, class T7, class T8>
        PK_FinalTemplate(const T1 &v1, const T2 &v2, const T3 &v3, const T4 &v4, const T5 &v5, const T6 &v6, const T7 &v7, const T8 &v8)
                {this->AccessKey().Initialize(v1, v2, v3, v4, v5, v6, v7, v8);}

        template <class T1, class T2>
        PK_FinalTemplate(T1 &v1, const T2 &v2)
                {this->AccessKey().Initialize(v1, v2);}

        template <class T1, class T2, class T3>
        PK_FinalTemplate(T1 &v1, const T2 &v2, const T3 &v3)
                {this->AccessKey().Initialize(v1, v2, v3);}

        template <class T1, class T2, class T3, class T4>
        PK_FinalTemplate(T1 &v1, const T2 &v2, const T3 &v3, const T4 &v4)
                {this->AccessKey().Initialize(v1, v2, v3, v4);}

        template <class T1, class T2, class T3, class T4, class T5>
        PK_FinalTemplate(T1 &v1, const T2 &v2, const T3 &v3, const T4 &v4, const T5 &v5)
                {this->AccessKey().Initialize(v1, v2, v3, v4, v5);}

        template <class T1, class T2, class T3, class T4, class T5, class T6>
        PK_FinalTemplate(T1 &v1, const T2 &v2, const T3 &v3, const T4 &v4, const T5 &v5, const T6 &v6)
                {this->AccessKey().Initialize(v1, v2, v3, v4, v5, v6);}

        template <class T1, class T2, class T3, class T4, class T5, class T6, class T7>
        PK_FinalTemplate(T1 &v1, const T2 &v2, const T3 &v3, const T4 &v4, const T5 &v5, const T6 &v6, const T7 &v7)
                {this->AccessKey().Initialize(v1, v2, v3, v4, v5, v6, v7);}

        template <class T1, class T2, class T3, class T4, class T5, class T6, class T7, class T8>
        PK_FinalTemplate(T1 &v1, const T2 &v2, const T3 &v3, const T4 &v4, const T5 &v5, const T6 &v6, const T7 &v7, const T8 &v8)
                {this->AccessKey().Initialize(v1, v2, v3, v4, v5, v6, v7, v8);}

#endif
};

//! \brief Base class for public key encryption standard classes.
//! \details These classes are used to select from variants of algorithms.
//!   Not all standards apply to all algorithms.
struct EncryptionStandard {};

//! \brief Base class for public key signature standard classes.
//! \details These classes are used to select from variants of algorithms.
//!   Not all standards apply to all algorithms.
struct SignatureStandard {};

//! \brief Trapdoor Function (TF) encryption scheme
//! \tparam STANDARD standard
//! \tparam KEYS keys used in the encryption scheme
//! \tparam ALG_INFO algorithm information
template <class STANDARD, class KEYS, class ALG_INFO>
class TF_ES;

template <class STANDARD, class KEYS, class ALG_INFO = TF_ES<STANDARD, KEYS, int> >
class TF_ES : public KEYS
{
        typedef typename STANDARD::EncryptionMessageEncodingMethod MessageEncodingMethod;

public:
        //! see EncryptionStandard for a list of standards
        typedef STANDARD Standard;
        typedef TF_CryptoSchemeOptions<ALG_INFO, KEYS, MessageEncodingMethod> SchemeOptions;

        static std::string CRYPTOPP_API StaticAlgorithmName() {return std::string(KEYS::StaticAlgorithmName()) + "/" + MessageEncodingMethod::StaticAlgorithmName();}

        //! implements PK_Decryptor interface
        typedef PK_FinalTemplate<TF_DecryptorImpl<SchemeOptions> > Decryptor;
        //! implements PK_Encryptor interface
        typedef PK_FinalTemplate<TF_EncryptorImpl<SchemeOptions> > Encryptor;
};

//! \class TF_SS
//! \brief Trapdoor Function (TF) Signature Scheme
//! \tparam STANDARD standard
//! \tparam H hash function
//! \tparam KEYS keys used in the signature scheme
//! \tparam ALG_INFO algorithm information
template <class STANDARD, class H, class KEYS, class ALG_INFO>  // VC60 workaround: doesn't work if KEYS is first parameter
class TF_SS;

template <class STANDARD, class H, class KEYS, class ALG_INFO = TF_SS<STANDARD, H, KEYS, int> > // VC60 workaround: doesn't work if KEYS is first parameter
class TF_SS : public KEYS
{
public:
        //! see SignatureStandard for a list of standards
        typedef STANDARD Standard;
        typedef typename Standard::SignatureMessageEncodingMethod MessageEncodingMethod;
        typedef TF_SignatureSchemeOptions<ALG_INFO, KEYS, MessageEncodingMethod, H> SchemeOptions;

        static std::string CRYPTOPP_API StaticAlgorithmName() {return std::string(KEYS::StaticAlgorithmName()) + "/" + MessageEncodingMethod::StaticAlgorithmName() + "(" + H::StaticAlgorithmName() + ")";}

        //! implements PK_Signer interface
        typedef PK_FinalTemplate<TF_SignerImpl<SchemeOptions> > Signer;
        //! implements PK_Verifier interface
        typedef PK_FinalTemplate<TF_VerifierImpl<SchemeOptions> > Verifier;
};

//! \class DL_SS
//! \brief Discrete Log (DL) signature scheme
//! \tparam KEYS keys used in the signature scheme
//! \tparam SA signature algorithm
//! \tparam MEM message encoding method
//! \tparam H hash function
//! \tparam ALG_INFO algorithm information
template <class KEYS, class SA, class MEM, class H, class ALG_INFO>
class DL_SS;

template <class KEYS, class SA, class MEM, class H, class ALG_INFO = DL_SS<KEYS, SA, MEM, H, int> >
class DL_SS : public KEYS
{
        typedef DL_SignatureSchemeOptions<ALG_INFO, KEYS, SA, MEM, H> SchemeOptions;

public:
        static std::string StaticAlgorithmName() {return SA::StaticAlgorithmName() + std::string("/EMSA1(") + H::StaticAlgorithmName() + ")";}

        //! implements PK_Signer interface
        typedef PK_FinalTemplate<DL_SignerImpl<SchemeOptions> > Signer;
        //! implements PK_Verifier interface
        typedef PK_FinalTemplate<DL_VerifierImpl<SchemeOptions> > Verifier;
};

//! \brief Discrete Log (DL) encryption scheme
//! \tparam KEYS keys used in the encryption scheme
//! \tparam AA key agreement algorithm
//! \tparam DA key derivation algorithm
//! \tparam EA encryption algorithm
//! \tparam ALG_INFO algorithm information
template <class KEYS, class AA, class DA, class EA, class ALG_INFO>
class DL_ES : public KEYS
{
        typedef DL_CryptoSchemeOptions<ALG_INFO, KEYS, AA, DA, EA> SchemeOptions;

public:
        //! implements PK_Decryptor interface
        typedef PK_FinalTemplate<DL_DecryptorImpl<SchemeOptions> > Decryptor;
        //! implements PK_Encryptor interface
        typedef PK_FinalTemplate<DL_EncryptorImpl<SchemeOptions> > Encryptor;
};

NAMESPACE_END

#if CRYPTOPP_MSC_VERSION
# pragma warning(pop)
#endif

#endif