ext-cryptopp/seckey.h

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

/// \file seckey.h
/// \brief Classes and functions for implementing secret key algorithms.

#ifndef CRYPTOPP_SECKEY_H
#define CRYPTOPP_SECKEY_H

#include "config.h"
#include "cryptlib.h"
#include "misc.h"
#include "simple.h"

#if CRYPTOPP_MSC_VERSION
# pragma warning(push)
# pragma warning(disable: 4189)
#endif

// Issue 340
#if CRYPTOPP_GCC_DIAGNOSTIC_AVAILABLE
# pragma GCC diagnostic push
# pragma GCC diagnostic ignored "-Wconversion"
# pragma GCC diagnostic ignored "-Wsign-conversion"
#endif

NAMESPACE_BEGIN(CryptoPP)

/// \brief Inverts the cipher's direction
/// \param dir the cipher's direction
/// \returns DECRYPTION if \ref CipherDir "dir" is ENCRYPTION, DECRYPTION otherwise
inline CipherDir ReverseCipherDir(CipherDir dir)
{
	return (dir == ENCRYPTION) ? DECRYPTION : ENCRYPTION;
}

/// \class FixedBlockSize
/// \brief Inherited by algorithms with fixed block size
/// \tparam N the blocksize of the algorithm
template <unsigned int N>
class FixedBlockSize
{
public:
	/// \brief The block size of the algorithm provided as a constant.
	CRYPTOPP_CONSTANT(BLOCKSIZE = N)
	/// \brief The default blocksize for the algorithm provided as a constant.
	CRYPTOPP_CONSTANT(DEFAULT_BLOCKSIZE = N)
	/// \brief The minimum blocksize for the algorithm provided as a constant.
	CRYPTOPP_CONSTANT(MIN_BLOCKSIZE = N)
	/// \brief The maximum blocksize for the algorithm provided as a constant.
	CRYPTOPP_CONSTANT(MAX_BLOCKSIZE = N)
	/// \brief The default block size for the algorithm provided by a static function.
	/// \param blocksize the block size, in bytes
	/// \details The default implementation returns BLOCKSIZE. blocksize is unused
	///   in the default implementation.
	CRYPTOPP_STATIC_CONSTEXPR size_t CRYPTOPP_API StaticGetValidBlockSize(size_t blocksize)
	{
		return CRYPTOPP_UNUSED(blocksize), static_cast<size_t>(BLOCKSIZE);
	}
	/// \brief The default block size under a key provided by a static function.
	/// \param keylength the size of the key, in bytes
	/// \param blocksize the block size, in bytes
	/// \details The default implementation returns BLOCKSIZE. blocksize is unused
	///   in the default implementation.
	CRYPTOPP_STATIC_CONSTEXPR size_t CRYPTOPP_API StaticGetValidBlockSize(size_t keylength, size_t blocksize)
	{
		return CRYPTOPP_UNUSED(keylength), CRYPTOPP_UNUSED(blocksize), static_cast<size_t>(BLOCKSIZE);
	}
};

// ************** rounds ***************

/// \class FixedRounds
/// \brief Inherited by algorithms with fixed number of rounds
/// \tparam R the number of rounds used by the algorithm
template <unsigned int R>
class FixedRounds
{
public:
	/// \brief The number of rounds for the algorithm provided as a constant.
	CRYPTOPP_CONSTANT(ROUNDS = R)
};

/// \class VariableRounds
/// \brief Inherited by algorithms with variable number of rounds
/// \tparam D Default number of rounds
/// \tparam N Minimum number of rounds
/// \tparam M Maximum number of rounds
template <unsigned int D, unsigned int N=1, unsigned int M=INT_MAX>		// use INT_MAX here because enums are treated as signed ints
class VariableRounds
{
public:
	/// \brief The default number of rounds for the algorithm provided as a constant.
	CRYPTOPP_CONSTANT(DEFAULT_ROUNDS = D)
	/// \brief The minimum number of rounds for the algorithm provided as a constant.
	CRYPTOPP_CONSTANT(MIN_ROUNDS = N)
	/// \brief The maximum number of rounds for the algorithm provided as a constant.
	CRYPTOPP_CONSTANT(MAX_ROUNDS = M)
	/// \brief The default number of rounds for the algorithm based on key length
	///   provided by a static function.
	/// \param keylength the size of the key, in bytes
	/// \details keylength is unused in the default implementation.
	CRYPTOPP_STATIC_CONSTEXPR unsigned int StaticGetDefaultRounds(size_t keylength)
	{
		return CRYPTOPP_UNUSED(keylength), static_cast<unsigned int>(DEFAULT_ROUNDS);
	}

protected:
	/// \brief Validates the number of rounds for an algorithm.
	/// \param rounds the candidate number of rounds
	/// \param alg an Algorithm object used if the number of rounds are invalid
	/// \throws InvalidRounds if the number of rounds are invalid
	/// \details ThrowIfInvalidRounds() validates the number of rounds and throws if invalid.
	inline void ThrowIfInvalidRounds(int rounds, const Algorithm *alg)
	{
		if (M == INT_MAX) // Coverity and result_independent_of_operands
		{
			if (rounds < MIN_ROUNDS)
				throw InvalidRounds(alg ? alg->AlgorithmName() : std::string("VariableRounds"), rounds);
		}
		else
		{
			if (rounds < MIN_ROUNDS || rounds > MAX_ROUNDS)
				throw InvalidRounds(alg ? alg->AlgorithmName() : std::string("VariableRounds"), rounds);
		}
	}

	/// \brief Validates the number of rounds for an algorithm
	/// \param param the candidate number of rounds
	/// \param alg an Algorithm object used if the number of rounds are invalid
	/// \returns the number of rounds for the algorithm
	/// \throws InvalidRounds if the number of rounds are invalid
	/// \details GetRoundsAndThrowIfInvalid() validates the number of rounds and throws if invalid.
	inline unsigned int GetRoundsAndThrowIfInvalid(const NameValuePairs &param, const Algorithm *alg)
	{
		int rounds = param.GetIntValueWithDefault("Rounds", DEFAULT_ROUNDS);
		ThrowIfInvalidRounds(rounds, alg);
		return static_cast<unsigned int>(rounds);
	}
};

/// \class VariableBlockSize
/// \brief Inherited by algorithms with variable blocksize
/// \tparam D Default blocksize
/// \tparam N Minimum blocksize
/// \tparam M Maximum blocksize
template <unsigned int D, unsigned int N=1, unsigned int M=INT_MAX>		// use INT_MAX here because enums are treated as signed ints
class VariableBlockSize
{
public:
	/// \brief The default blocksize for the algorithm provided as a constant.
	CRYPTOPP_CONSTANT(DEFAULT_BLOCKSIZE = D)
	/// \brief The minimum blocksize for the algorithm provided as a constant.
	CRYPTOPP_CONSTANT(MIN_BLOCKSIZE = N)
	/// \brief The maximum blocksize for the algorithm provided as a constant.
	CRYPTOPP_CONSTANT(MAX_BLOCKSIZE = M)
	/// \brief The default block size for the algorithm provided by a static function.
	/// \param blocksize the block size, in bytes
	/// \details The default implementation returns BLOCKSIZE. blocksize is unused
	///   in the default implementation.
	CRYPTOPP_STATIC_CONSTEXPR size_t CRYPTOPP_API StaticGetValidBlockSize(size_t blocksize)
	{
		return CRYPTOPP_UNUSED(blocksize), static_cast<size_t>(DEFAULT_BLOCKSIZE);
	}
	/// \brief The default block size under a key provided by a static function.
	/// \param keylength the size of the key, in bytes
	/// \param blocksize the block size, in bytes
	/// \details The default implementation returns BLOCKSIZE. blocksize is unused
	///   in the default implementation.
	CRYPTOPP_STATIC_CONSTEXPR size_t CRYPTOPP_API StaticGetValidBlockSize(size_t keylength, size_t blocksize)
	{
		return CRYPTOPP_UNUSED(keylength), CRYPTOPP_UNUSED(blocksize), static_cast<size_t>(DEFAULT_BLOCKSIZE);
	}

protected:
	/// \brief Validates the blocksize for an algorithm.
	/// \param blocksize the candidate blocksize
	/// \param alg an Algorithm object used if the blocksize is invalid
	/// \throws InvalidBlockSize if the blocksize is invalid
	/// \details ThrowIfInvalidBlockSize() validates the blocksize and throws if invalid.
	inline void ThrowIfInvalidBlockSize(int blocksize, const Algorithm *alg)
	{
		if (M == INT_MAX) // Coverity and result_independent_of_operands
		{
			if (blocksize < MIN_BLOCKSIZE)
				throw InvalidBlockSize(alg ? alg->AlgorithmName() : std::string("VariableBlockSize"), blocksize);
		}
		else
		{
			if (blocksize < MIN_BLOCKSIZE || blocksize > MAX_BLOCKSIZE)
				throw InvalidBlockSize(alg ? alg->AlgorithmName() : std::string("VariableBlockSize"), blocksize);
		}
	}

	/// \brief Validates the blocksize for an algorithm
	/// \param param the candidate blocksize
	/// \param alg an Algorithm object used if the blocksize is invalid
	/// \returns the blocksize for the algorithm
	/// \throws InvalidBlockSize if the blocksize is invalid
	/// \details GetBlockSizeAndThrowIfInvalid() validates the blocksize and throws if invalid.
	inline unsigned int GetBlockSizeAndThrowIfInvalid(const NameValuePairs &param, const Algorithm *alg)
	{
		int keylength = param.GetIntValueWithDefault("KeySize", 0);
		int blocksize = param.GetIntValueWithDefault("BlockSize", DEFAULT_BLOCKSIZE);
		if (keylength > 0)
			ThrowIfInvalidBlockSize(keylength, blocksize, alg);
		else
			ThrowIfInvalidBlockSize(blocksize, alg);
		return static_cast<unsigned int>(blocksize);
	}

	/// Provides the block size of the cipher
	/// \return the block size, in bytes
	/// \details The sematics of BlockSize() is return DEFAULT_BLOCKSIZE if the default blocksize
	///   is in effect. If the blocksize has changed, then the value returned is the BlockSize()
	///   parameter used during SetKey().
	/// \details DEFAULT_BLOCKSIZE should be paired with DEFAULT_KEYLENGTH, and it is the same as
	///    BLOCKSIZE in a FixedBlockSize cipher.
	virtual unsigned int BlockSize() const =0;

	/// Provides the minimum block size of the cipher
	/// \return the minimum block size, in bytes
	/// \details MinBlockSize() returns the smallest blocksize a cipher can use. The size can
	///   be affected by the key length. For example, Threefish has key sizes of 256, 512 and 1024 bits,
	///   and the blocksize follows the key length. If a 512-bit key is used, then the block size is 512
	///   bits. Once keyed, the minimum block size of 256 is not accurate, nor is a block size of 1024 bit.
	virtual unsigned int MinBlockSize() const
		{ return MIN_BLOCKSIZE; }

	/// Provides the maximum block size of the cipher
	/// \return the maximum block size, in bytes
	/// \details MaxBlockSize() returns the largest blocksize a cipher can use. The size can
	///   be affected by the key length. For example, Threefish has key sizes of 256, 512 and 1024 bits,
	///   and the blocksize follows the key length. If a 512-bit key is used, then the block size is 512
	///   bits. Once keyed, the minimum block size of 256 is not accurate, nor is a block size of 1024 bit.
	virtual unsigned int MaxBlockSize() const
		{ return MAX_BLOCKSIZE; }

	/// Provides the initialization vector length of the cipher
	/// \return the initialization vector length, in bytes
	/// \details The sematics of IVSize() is return IV_LENGTH if the default blocksize is
	///   in effect. If the blocksize has changed, then the default implentation returns the value of
	///   the BlockSize() parameter used during SetKey().
	/// \details Derived classes may override the behavior such that a different value is returned.
	///   This may happen with a cipher that requires an IV that is twice the block size.
	virtual unsigned int IVSize() const =0;

	/// \brief Provides the minimum size of an IV
	/// \return minimal length of IVs accepted by this cipher, in bytes
	virtual unsigned int MinIVLength() const
		{ return MIN_BLOCKSIZE; }

	/// \brief Provides the maximum size of an IV
	/// \return maximal length of IVs accepted by this cipher, in bytes
	virtual unsigned int MaxIVLength() const
		{ return MAX_BLOCKSIZE; }
};

// ************** key length ***************

/// \class FixedKeyLength
/// \brief Inherited by keyed algorithms with fixed key length
/// \tparam N Default key length, in bytes
/// \tparam IV_REQ the \ref SimpleKeyingInterface::IV_Requirement "IV requirements"
/// \tparam IV_L default IV length, in bytes
/// \sa SimpleKeyingInterface
template <unsigned int N, unsigned int IV_REQ = SimpleKeyingInterface::NOT_RESYNCHRONIZABLE, unsigned int IV_L = 0>
class FixedKeyLength
{
public:
	/// \brief The default key length used by the algorithm provided as a constant
	/// \details KEYLENGTH is provided in bytes, not bits
	CRYPTOPP_CONSTANT(KEYLENGTH=N)
	/// \brief The minimum key length used by the algorithm provided as a constant
	/// \details MIN_KEYLENGTH is provided in bytes, not bits
	CRYPTOPP_CONSTANT(MIN_KEYLENGTH=N)
	/// \brief The maximum key length used by the algorithm provided as a constant
	/// \details MAX_KEYLENGTH is provided in bytes, not bits
	CRYPTOPP_CONSTANT(MAX_KEYLENGTH=N)
	/// \brief The default key length used by the algorithm provided as a constant
	/// \details DEFAULT_KEYLENGTH is provided in bytes, not bits
	CRYPTOPP_CONSTANT(DEFAULT_KEYLENGTH=N)
	/// \brief The default IV requirements for the algorithm provided as a constant
	/// \details The default value is NOT_RESYNCHRONIZABLE. See IV_Requirement
	///  in cryptlib.h for allowed values.
	CRYPTOPP_CONSTANT(IV_REQUIREMENT = IV_REQ)
	/// \brief The default IV length used by the algorithm provided as a constant
	/// \details IV_LENGTH is provided in bytes, not bits. The default implementation uses 0.
	CRYPTOPP_CONSTANT(IV_LENGTH = IV_L)
	/// \brief The default key length for the algorithm provided by a static function.
	/// \param keylength the size of the key, in bytes
	/// \details The default implementation returns KEYLENGTH. keylength is unused
	///   in the default implementation.
	CRYPTOPP_STATIC_CONSTEXPR size_t CRYPTOPP_API StaticGetValidKeyLength(size_t keylength)
	{
		return CRYPTOPP_UNUSED(keylength), static_cast<size_t>(KEYLENGTH);
	}
};

/// \class VariableKeyLength
/// \brief Inherited by keyed algorithms with variable key length
/// \tparam D Default key length, in bytes
/// \tparam N Minimum key length, in bytes
/// \tparam M Maximum key length, in bytes
/// \tparam Q Default key length multiple, in bytes. The default multiple is 1.
/// \tparam IV_REQ the \ref SimpleKeyingInterface::IV_Requirement "IV requirements"
/// \tparam IV_L default IV length, in bytes. The default length is 0.
/// \sa SimpleKeyingInterface
template <unsigned int D, unsigned int N, unsigned int M, unsigned int Q = 1, unsigned int IV_REQ = SimpleKeyingInterface::NOT_RESYNCHRONIZABLE, unsigned int IV_L = 0>
class VariableKeyLength
{
	// Make these private to avoid Doxygen documenting them in all derived classes
	CRYPTOPP_COMPILE_ASSERT(Q > 0);
	CRYPTOPP_COMPILE_ASSERT(N % Q == 0);
	CRYPTOPP_COMPILE_ASSERT(M % Q == 0);
	CRYPTOPP_COMPILE_ASSERT(N < M);
	CRYPTOPP_COMPILE_ASSERT(D >= N);
	CRYPTOPP_COMPILE_ASSERT(M >= D);

public:
	/// \brief The minimum key length used by the algorithm provided as a constant
	/// \details MIN_KEYLENGTH is provided in bytes, not bits
	CRYPTOPP_CONSTANT(MIN_KEYLENGTH=N)
	/// \brief The maximum key length used by the algorithm provided as a constant
	/// \details MAX_KEYLENGTH is provided in bytes, not bits
	CRYPTOPP_CONSTANT(MAX_KEYLENGTH=M)
	/// \brief The default key length used by the algorithm provided as a constant
	/// \details DEFAULT_KEYLENGTH is provided in bytes, not bits
	CRYPTOPP_CONSTANT(DEFAULT_KEYLENGTH=D)
	/// \brief The key length multiple used by the algorithm provided as a constant
	/// \details MAX_KEYLENGTH is provided in bytes, not bits
	CRYPTOPP_CONSTANT(KEYLENGTH_MULTIPLE=Q)
	/// \brief The default IV requirements for the algorithm provided as a constant
	/// \details The default value is NOT_RESYNCHRONIZABLE. See IV_Requirement
	///  in cryptlib.h for allowed values.
	CRYPTOPP_CONSTANT(IV_REQUIREMENT=IV_REQ)
	/// \brief The default initialization vector length for the algorithm provided as a constant
	/// \details IV_LENGTH is provided in bytes, not bits. The default implementation uses 0.
	CRYPTOPP_CONSTANT(IV_LENGTH=IV_L)
	/// \brief Provides a valid key length for the algorithm provided by a static function.
	/// \param keylength the size of the key, in bytes
	/// \details If keylength is less than MIN_KEYLENGTH, then the function returns
	///   MIN_KEYLENGTH. If keylength is greater than MAX_KEYLENGTH, then the function
	///   returns MAX_KEYLENGTH. If keylength is a multiple of KEYLENGTH_MULTIPLE,
	///   then keylength is returned. Otherwise, the function returns keylength rounded
	///   \a down to the next smaller multiple of KEYLENGTH_MULTIPLE.
	/// \details keylength is provided in bytes, not bits.
	CRYPTOPP_STATIC_CONSTEXPR size_t CRYPTOPP_API StaticGetValidKeyLength(size_t keylength)
	{
		return (keylength <= N) ? N :
			(keylength >= M) ? M :
			(keylength+Q-1) - (keylength+Q-1)%Q;
	}
};

/// \class SameKeyLengthAs
/// \brief Provides key lengths based on another class's key length
/// \tparam T another FixedKeyLength or VariableKeyLength class
/// \tparam IV_REQ the \ref SimpleKeyingInterface::IV_Requirement "IV requirements"
/// \tparam IV_L default IV length, in bytes
/// \sa SimpleKeyingInterface
template <class T, unsigned int IV_REQ = SimpleKeyingInterface::NOT_RESYNCHRONIZABLE, unsigned int IV_L = 0>
class SameKeyLengthAs
{
public:
	/// \brief The minimum key length used by the algorithm provided as a constant
	/// \details MIN_KEYLENGTH is provided in bytes, not bits
	CRYPTOPP_CONSTANT(MIN_KEYLENGTH=T::MIN_KEYLENGTH)
	/// \brief The maximum key length used by the algorithm provided as a constant
	/// \details MIN_KEYLENGTH is provided in bytes, not bits
	CRYPTOPP_CONSTANT(MAX_KEYLENGTH=T::MAX_KEYLENGTH)
	/// \brief The default key length used by the algorithm provided as a constant
	/// \details MIN_KEYLENGTH is provided in bytes, not bits
	CRYPTOPP_CONSTANT(DEFAULT_KEYLENGTH=T::DEFAULT_KEYLENGTH)
	/// \brief The default IV requirements for the algorithm provided as a constant
	/// \details The default value is NOT_RESYNCHRONIZABLE. See IV_Requirement
	///  in cryptlib.h for allowed values.
	CRYPTOPP_CONSTANT(IV_REQUIREMENT=IV_REQ)
	/// \brief The default initialization vector length for the algorithm provided as a constant
	/// \details IV_LENGTH is provided in bytes, not bits. The default implementation uses 0.
	CRYPTOPP_CONSTANT(IV_LENGTH=IV_L)
	/// \brief Provides a valid key length for the algorithm provided by a static function.
	/// \param keylength the size of the key, in bytes
	/// \details If keylength is less than MIN_KEYLENGTH, then the function returns
	///   MIN_KEYLENGTH. If keylength is greater than MAX_KEYLENGTH, then the function
	///   returns MAX_KEYLENGTH. If keylength is a multiple of KEYLENGTH_MULTIPLE,
	///   then keylength is returned. Otherwise, the function returns keylength rounded
	///   \a down to the next smaller multiple of KEYLENGTH_MULTIPLE.
	/// \details keylength is provided in bytes, not bits.
	CRYPTOPP_STATIC_CONSTEXPR size_t CRYPTOPP_API StaticGetValidKeyLength(size_t keylength)
		{return T::StaticGetValidKeyLength(keylength);}
};

// ************** implementation helper for SimpleKeyingInterface ***************

/// \class SimpleKeyingInterfaceImpl
/// \brief Provides a base implementation of SimpleKeyingInterface
/// \tparam BASE a SimpleKeyingInterface derived class
/// \tparam INFO a SimpleKeyingInterface derived class
/// \details SimpleKeyingInterfaceImpl() provides a default implementation for ciphers providing a keying interface.
///   Functions are virtual and not eligible for C++11 <tt>constexpr</tt>-ness.
/// \sa Algorithm(), SimpleKeyingInterface()
template <class BASE, class INFO = BASE>
class CRYPTOPP_NO_VTABLE SimpleKeyingInterfaceImpl : public BASE
{
public:
	/// \brief The minimum key length used by the algorithm
	/// \returns minimum key length used by the algorithm, in bytes
	size_t MinKeyLength() const
		{return INFO::MIN_KEYLENGTH;}

	/// \brief The maximum key length used by the algorithm
	/// \returns maximum key length used by the algorithm, in bytes
	size_t MaxKeyLength() const
		{return (size_t)INFO::MAX_KEYLENGTH;}

	/// \brief The default key length used by the algorithm
	/// \returns default key length used by the algorithm, in bytes
	size_t DefaultKeyLength() const
		{return INFO::DEFAULT_KEYLENGTH;}

	/// \brief Provides a valid key length for the algorithm
	/// \param keylength the size of the key, in bytes
	/// \returns the valid key length, in bytes
	/// \details keylength is provided in bytes, not bits. If keylength is less than MIN_KEYLENGTH,
	///   then the function returns MIN_KEYLENGTH. If keylength is greater than MAX_KEYLENGTH,
	///   then the function returns MAX_KEYLENGTH. if If keylength is a multiple of KEYLENGTH_MULTIPLE,
	///   then keylength is returned. Otherwise, the function returns a \a lower multiple of
	///   KEYLENGTH_MULTIPLE.
	size_t GetValidKeyLength(size_t keylength) const {return INFO::StaticGetValidKeyLength(keylength);}

	/// \brief The default IV requirements for the algorithm
	/// \details The default value is NOT_RESYNCHRONIZABLE. See IV_Requirement
	///  in cryptlib.h for allowed values.
	SimpleKeyingInterface::IV_Requirement IVRequirement() const
		{return (SimpleKeyingInterface::IV_Requirement)INFO::IV_REQUIREMENT;}

	/// \brief The default initialization vector length for the algorithm
	/// \details IVSize is provided in bytes, not bits. The default implementation uses IV_LENGTH, which is 0.
	unsigned int IVSize() const
		{return INFO::IV_LENGTH;}
};

/// \class BlockCipherImpl
/// \brief Provides a base implementation of Algorithm and SimpleKeyingInterface for block ciphers
/// \tparam INFO a SimpleKeyingInterface derived class
/// \tparam BASE a SimpleKeyingInterface derived class
/// \details BlockCipherImpl() provides a default implementation for block ciphers using AlgorithmImpl()
///   and SimpleKeyingInterfaceImpl(). Functions are virtual and not eligible for C++11 <tt>constexpr</tt>-ness.
/// \sa Algorithm(), SimpleKeyingInterface(), AlgorithmImpl(), SimpleKeyingInterfaceImpl()
template <class INFO, class BASE = BlockCipher>
class CRYPTOPP_NO_VTABLE BlockCipherImpl : public AlgorithmImpl<SimpleKeyingInterfaceImpl<TwoBases<BASE, INFO> > >
{
public:
	/// Provides the block size of the algorithm
	/// \returns the block size of the algorithm, in bytes
	unsigned int BlockSize() const {return this->BLOCKSIZE;}
};

/// \class VariableBlockCipherImpl
/// \brief Provides a base implementation of Algorithm and SimpleKeyingInterface for block ciphers with varibale block sizes
/// \tparam INFO a SimpleKeyingInterface derived class
/// \tparam BASE a SimpleKeyingInterface derived class
/// \details VariableBlockCipherImpl() provides a default implementation for block ciphers with varibale block sizes using AlgorithmImpl()
///   and SimpleKeyingInterfaceImpl().
/// \sa Algorithm(), SimpleKeyingInterface(), AlgorithmImpl(), SimpleKeyingInterfaceImpl()
template <class INFO, class BASE = BlockCipher>
class CRYPTOPP_NO_VTABLE VariableBlockCipherImpl : public AlgorithmImpl<SimpleKeyingInterfaceImpl<TwoBases<BASE, INFO> > >
{
public:
	VariableBlockCipherImpl() : m_blocksize(0), m_ivlength(0) {}
	VariableBlockCipherImpl(unsigned int blockSize) : m_blocksize(blockSize), m_ivlength(blockSize) {}
	VariableBlockCipherImpl(unsigned int blockSize, unsigned int ivLength) : m_blocksize(blockSize), m_ivlength(ivLength) {}

	/// Provides the block size of the algorithm
	/// \returns the block size, in bytes
	unsigned int BlockSize() const {
		return m_blocksize ? m_blocksize :
			static_cast<unsigned int>(this->DEFAULT_BLOCKSIZE);
	}

	/// Provides the initialization vector length of the algorithm
	/// \returns the initialization vector length, in bytes
	unsigned int IVSize() const {
		if (!this->IsResynchronizable())
			throw NotImplemented(this->GetAlgorithm().AlgorithmName() + ": this object doesn't support resynchronization");
		return m_ivlength ? m_ivlength :
			static_cast<unsigned int>(this->IV_LENGTH);
	}

protected:
	unsigned int m_blocksize, m_ivlength;
};

/// \class BlockCipherFinal
/// \brief Provides class member functions to key a block cipher
/// \tparam DIR a CipherDir
/// \tparam BASE a BlockCipherImpl derived class
template <CipherDir DIR, class BASE>
class BlockCipherFinal : public ClonableImpl<BlockCipherFinal<DIR, BASE>, BASE>
{
public:
	/// \brief Construct a default BlockCipherFinal
	/// \details The cipher is not keyed.
 	BlockCipherFinal() {}

	/// \brief Construct a BlockCipherFinal
	/// \param key a byte array used to key the cipher
	/// \details key must be at least DEFAULT_KEYLENGTH in length. Internally, the function calls
	///    SimpleKeyingInterface::SetKey.
	BlockCipherFinal(const byte *key)
		{this->SetKey(key, this->DEFAULT_KEYLENGTH);}

	/// \brief Construct a BlockCipherFinal
	/// \param key a byte array used to key the cipher
	/// \param length the length of the byte array
	/// \details key must be at least DEFAULT_KEYLENGTH in length. Internally, the function calls
	///    SimpleKeyingInterface::SetKey.
	BlockCipherFinal(const byte *key, size_t length)
		{this->SetKey(key, length);}

	/// \brief Construct a BlockCipherFinal
	/// \param key a byte array used to key the cipher
	/// \param length the length of the byte array
	/// \param rounds the number of rounds
	/// \details key must be at least DEFAULT_KEYLENGTH in length. Internally, the function calls
	///    SimpleKeyingInterface::SetKeyWithRounds.
	BlockCipherFinal(const byte *key, size_t length, unsigned int rounds)
		{this->SetKeyWithRounds(key, length, rounds);}

	/// \brief Provides the direction of the cipher
	/// \returns true if DIR is ENCRYPTION, false otherwise
	/// \sa GetCipherDirection(), IsPermutation()
	bool IsForwardTransformation() const {return DIR == ENCRYPTION;}
};

/// \class MessageAuthenticationCodeImpl
/// \brief Provides a base implementation of Algorithm and SimpleKeyingInterface for message authentication codes
/// \tparam INFO a SimpleKeyingInterface derived class
/// \tparam BASE a SimpleKeyingInterface derived class
/// \details MessageAuthenticationCodeImpl() provides a default implementation for message authentication codes
///   using AlgorithmImpl() and SimpleKeyingInterfaceImpl(). Functions are virtual and not subject to C++11
///   <tt>constexpr</tt>.
/// \sa Algorithm(), SimpleKeyingInterface(), AlgorithmImpl(), SimpleKeyingInterfaceImpl()
template <class BASE, class INFO = BASE>
class MessageAuthenticationCodeImpl : public AlgorithmImpl<SimpleKeyingInterfaceImpl<BASE, INFO>, INFO>
{
};

/// \class MessageAuthenticationCodeFinal
/// \brief Provides class member functions to key a message authentication code
/// \tparam BASE a BlockCipherImpl derived class
/// \details A default implementation for MessageAuthenticationCode
template <class BASE>
class MessageAuthenticationCodeFinal : public ClonableImpl<MessageAuthenticationCodeFinal<BASE>, MessageAuthenticationCodeImpl<BASE> >
{
public:
	/// \brief Construct a default MessageAuthenticationCodeFinal
	/// \details The message authentication code is not keyed.
 	MessageAuthenticationCodeFinal() {}
	/// \brief Construct a BlockCipherFinal
	/// \param key a byte array used to key the algorithm
	/// \details key must be at least DEFAULT_KEYLENGTH in length. Internally, the function calls
	///    SimpleKeyingInterface::SetKey.
	MessageAuthenticationCodeFinal(const byte *key)
		{this->SetKey(key, this->DEFAULT_KEYLENGTH);}
	/// \brief Construct a BlockCipherFinal
	/// \param key a byte array used to key the algorithm
	/// \param length the length of the byte array
	/// \details key must be at least DEFAULT_KEYLENGTH in length. Internally, the function calls
	///    SimpleKeyingInterface::SetKey.
	MessageAuthenticationCodeFinal(const byte *key, size_t length)
		{this->SetKey(key, length);}
};

// ************** documentation ***************

/// \class BlockCipherDocumentation
/// \brief Provides Encryption and Decryption typedefs used by derived classes to
///    implement a block cipher
/// \details These objects usually should not be used directly. See CipherModeDocumentation
///    instead. Each class derived from this one defines two types, Encryption and Decryption,
///    both of which implement the BlockCipher interface.
struct BlockCipherDocumentation
{
	/// implements the BlockCipher interface
	typedef BlockCipher Encryption;
	/// implements the BlockCipher interface
	typedef BlockCipher Decryption;
};

/// \class SymmetricCipherDocumentation
/// \brief Provides Encryption and Decryption typedefs used by derived classes to
///    implement a symmetric cipher
/// \details Each class derived from this one defines two types, Encryption and Decryption,
///    both of which implement the SymmetricCipher interface. Two types of classes derive
///    from this class: stream ciphers and block cipher modes. Stream ciphers can be used
///    alone, cipher mode classes need to be used with a block cipher. See CipherModeDocumentation
///    for more for information about using cipher modes and block ciphers.
struct SymmetricCipherDocumentation
{
	/// implements the SymmetricCipher interface
	typedef SymmetricCipher Encryption;
	/// implements the SymmetricCipher interface
	typedef SymmetricCipher Decryption;
};

/// \class AuthenticatedSymmetricCipherDocumentation
/// \brief Provides Encryption and Decryption typedefs used by derived classes to
///    implement an authenticated encryption cipher
/// \details Each class derived from this one defines two types, Encryption and Decryption,
///    both of which implement the AuthenticatedSymmetricCipher interface.
struct AuthenticatedSymmetricCipherDocumentation
{
	/// implements the AuthenticatedSymmetricCipher interface
	typedef AuthenticatedSymmetricCipher Encryption;
	/// implements the AuthenticatedSymmetricCipher interface
	typedef AuthenticatedSymmetricCipher Decryption;
};

NAMESPACE_END

#if CRYPTOPP_MSC_VERSION
# pragma warning(pop)
#endif

// Issue 340
#if CRYPTOPP_GCC_DIAGNOSTIC_AVAILABLE
# pragma GCC diagnostic pop
#endif

#endif