seckey.h

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

// This file contains helper classes/functions for implementing secret key algorithms.

#ifndef CRYPTOPP_SECKEY_H
#define CRYPTOPP_SECKEY_H

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

NAMESPACE_BEGIN(CryptoPP)

inline CipherDir ReverseCipherDir(CipherDir dir)
{
        return (dir == ENCRYPTION) ? DECRYPTION : ENCRYPTION;
}

//! to be inherited by block ciphers with fixed block size
template <unsigned int N>
class FixedBlockSize
{
public:
        CRYPTOPP_CONSTANT(BLOCKSIZE = N)
};

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

//! to be inherited by ciphers with fixed number of rounds
template <unsigned int R>
class FixedRounds
{
public:
        CRYPTOPP_CONSTANT(ROUNDS = R)
};

//! to be inherited by ciphers with variable 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:
        CRYPTOPP_CONSTANT(DEFAULT_ROUNDS = D)
        CRYPTOPP_CONSTANT(MIN_ROUNDS = N)
        CRYPTOPP_CONSTANT(MAX_ROUNDS = M)
        static unsigned int StaticGetDefaultRounds(size_t keylength) {return DEFAULT_ROUNDS;}

protected:
        inline void ThrowIfInvalidRounds(int rounds, const Algorithm *alg)
        {
                if (rounds < MIN_ROUNDS || rounds > MAX_ROUNDS)
                        throw InvalidRounds(alg->AlgorithmName(), rounds);
        }

        inline unsigned int GetRoundsAndThrowIfInvalid(const NameValuePairs &param, const Algorithm *alg)
        {
                int rounds = param.GetIntValueWithDefault("Rounds", DEFAULT_ROUNDS);
                ThrowIfInvalidRounds(rounds, alg);
                return (unsigned int)rounds;
        }
};

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

//! to be inherited by keyed algorithms with fixed key length
template <unsigned int N, unsigned int IV_REQ = SimpleKeyingInterface::NOT_RESYNCHRONIZABLE, unsigned int IV_L = 0>
class FixedKeyLength
{
public:
        CRYPTOPP_CONSTANT(KEYLENGTH=N)
        CRYPTOPP_CONSTANT(MIN_KEYLENGTH=N)
        CRYPTOPP_CONSTANT(MAX_KEYLENGTH=N)
        CRYPTOPP_CONSTANT(DEFAULT_KEYLENGTH=N)
        CRYPTOPP_CONSTANT(IV_REQUIREMENT = IV_REQ)
        CRYPTOPP_CONSTANT(IV_LENGTH = IV_L)
        static size_t CRYPTOPP_API StaticGetValidKeyLength(size_t) {return KEYLENGTH;}
};

/// support query of variable key length, template parameters are default, min, max, multiple (default multiple 1)
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:
        CRYPTOPP_CONSTANT(MIN_KEYLENGTH=N)
        CRYPTOPP_CONSTANT(MAX_KEYLENGTH=M)
        CRYPTOPP_CONSTANT(DEFAULT_KEYLENGTH=D)
        CRYPTOPP_CONSTANT(KEYLENGTH_MULTIPLE=Q)
        CRYPTOPP_CONSTANT(IV_REQUIREMENT=IV_REQ)
        CRYPTOPP_CONSTANT(IV_LENGTH=IV_L)

        static size_t CRYPTOPP_API StaticGetValidKeyLength(size_t n)
        {
                if (n < (size_t)MIN_KEYLENGTH)
                        return MIN_KEYLENGTH;
                else if (n > (size_t)MAX_KEYLENGTH)
                        return (size_t)MAX_KEYLENGTH;
                else
                {
                        n += KEYLENGTH_MULTIPLE-1;
                        return n - n%KEYLENGTH_MULTIPLE;
                }
        }
};

/// support query of key length that's the same as another class
template <class T>
class SameKeyLengthAs
{
public:
        CRYPTOPP_CONSTANT(MIN_KEYLENGTH=T::MIN_KEYLENGTH)
        CRYPTOPP_CONSTANT(MAX_KEYLENGTH=T::MAX_KEYLENGTH)
        CRYPTOPP_CONSTANT(DEFAULT_KEYLENGTH=T::DEFAULT_KEYLENGTH)
        CRYPTOPP_CONSTANT(IV_REQUIREMENT = T::IV_REQUIREMENT)
        CRYPTOPP_CONSTANT(IV_LENGTH = T::IV_LENGTH)
        static size_t CRYPTOPP_API StaticGetValidKeyLength(size_t keylength)
                {return T::StaticGetValidKeyLength(keylength);}
};

// ************** implementation helper for SimpleKeyed ***************

//! _
template <class BASE, class INFO = BASE>
class CRYPTOPP_NO_VTABLE SimpleKeyingInterfaceImpl : public BASE
{
public:
        size_t MinKeyLength() const {return INFO::MIN_KEYLENGTH;}
        size_t MaxKeyLength() const {return (size_t)INFO::MAX_KEYLENGTH;}
        size_t DefaultKeyLength() const {return INFO::DEFAULT_KEYLENGTH;}
        size_t GetValidKeyLength(size_t n) const {return INFO::StaticGetValidKeyLength(n);}
        typename BASE::IV_Requirement IVRequirement() const {return (typename BASE::IV_Requirement)INFO::IV_REQUIREMENT;}
        unsigned int IVSize() const {return INFO::IV_LENGTH;}
};

template <class INFO, class BASE = BlockCipher>
class CRYPTOPP_NO_VTABLE BlockCipherImpl : public AlgorithmImpl<SimpleKeyingInterfaceImpl<TwoBases<BASE, INFO> > >
{
public:
        unsigned int BlockSize() const {return this->BLOCKSIZE;}
};

//! _
template <CipherDir DIR, class BASE>
class BlockCipherFinal : public ClonableImpl<BlockCipherFinal<DIR, BASE>, BASE>
{
public:
        BlockCipherFinal() {}
        BlockCipherFinal(const byte *key)
                {this->SetKey(key, this->DEFAULT_KEYLENGTH);}
        BlockCipherFinal(const byte *key, size_t length)
                {this->SetKey(key, length);}
        BlockCipherFinal(const byte *key, size_t length, unsigned int rounds)
                {this->SetKeyWithRounds(key, length, rounds);}

        bool IsForwardTransformation() const {return DIR == ENCRYPTION;}
};

//! _
template <class BASE, class INFO = BASE>
class MessageAuthenticationCodeImpl : public AlgorithmImpl<SimpleKeyingInterfaceImpl<BASE, INFO>, INFO>
{
};

//! _
template <class BASE>
class MessageAuthenticationCodeFinal : public ClonableImpl<MessageAuthenticationCodeFinal<BASE>, MessageAuthenticationCodeImpl<BASE> >
{
public:
        MessageAuthenticationCodeFinal() {}
        MessageAuthenticationCodeFinal(const byte *key)
                {this->SetKey(key, this->DEFAULT_KEYLENGTH);}
        MessageAuthenticationCodeFinal(const byte *key, size_t length)
                {this->SetKey(key, length);}
};

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

//! 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;
};

/*! \brief 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;
};

NAMESPACE_END

#endif

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