eax.h

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

/// \file eax.h
/// \brief EAX block cipher mode of operation

#ifndef CRYPTOPP_EAX_H
#define CRYPTOPP_EAX_H

#include "authenc.h"
#include "modes.h"
#include "cmac.h"

NAMESPACE_BEGIN(CryptoPP)

/// \brief EAX block cipher base implementation
/// \details Base implementation of the AuthenticatedSymmetricCipher interface
/// \since Crypto++ 5.6.0
class CRYPTOPP_NO_VTABLE EAX_Base : public AuthenticatedSymmetricCipherBase
{
public:
    // AuthenticatedSymmetricCipher
    std::string AlgorithmName() const
        {return GetMAC().GetCipher().AlgorithmName() + std::string("/EAX");}
    std::string AlgorithmProvider() const
        {return GetMAC().GetCipher().AlgorithmProvider();}
    size_t MinKeyLength() const
        {return GetMAC().MinKeyLength();}
    size_t MaxKeyLength() const
        {return GetMAC().MaxKeyLength();}
    size_t DefaultKeyLength() const
        {return GetMAC().DefaultKeyLength();}
    size_t GetValidKeyLength(size_t n) const
        {return GetMAC().GetValidKeyLength(n);}
    bool IsValidKeyLength(size_t n) const
        {return GetMAC().IsValidKeyLength(n);}
    unsigned int OptimalDataAlignment() const
        {return GetMAC().OptimalDataAlignment();}
    IV_Requirement IVRequirement() const
        {return UNIQUE_IV;}
    unsigned int IVSize() const
        {return GetMAC().TagSize();}
    unsigned int MinIVLength() const
        {return 0;}
    unsigned int MaxIVLength() const
        {return UINT_MAX;}
    unsigned int DigestSize() const
        {return GetMAC().TagSize();}
    lword MaxHeaderLength() const
        {return LWORD_MAX;}
    lword MaxMessageLength() const
        {return LWORD_MAX;}

protected:
    // AuthenticatedSymmetricCipherBase
    bool AuthenticationIsOnPlaintext() const
        {return false;}
    unsigned int AuthenticationBlockSize() const
        {return 1;}
    void SetKeyWithoutResync(const byte *userKey, size_t keylength, const NameValuePairs &params);
    void Resync(const byte *iv, size_t len);
    size_t AuthenticateBlocks(const byte *data, size_t len);
    void AuthenticateLastHeaderBlock();
    void AuthenticateLastFooterBlock(byte *mac, size_t macSize);
    SymmetricCipher & AccessSymmetricCipher() {return m_ctr;}
    const CMAC_Base & GetMAC() const {return const_cast<EAX_Base *>(this)->AccessMAC();}
    virtual CMAC_Base & AccessMAC() =0;

    CTR_Mode_ExternalCipher::Encryption m_ctr;
};

/// \brief EAX block cipher final implementation
/// \tparam T_BlockCipher block cipher
/// \tparam T_IsEncryption direction in which to operate the cipher
/// \since Crypto++ 5.6.0
template <class T_BlockCipher, bool T_IsEncryption>
class EAX_Final : public EAX_Base
{
public:
    static std::string StaticAlgorithmName()
        {return T_BlockCipher::StaticAlgorithmName() + std::string("/EAX");}
    std::string AlgorithmProvider() const
        {return m_cmac.AlgorithmProvider();}
    bool IsForwardTransformation() const
        {return T_IsEncryption;}

private:
    CMAC_Base & AccessMAC() {return m_cmac;}
    CMAC<T_BlockCipher> m_cmac;
};

#ifdef EAX  // EAX is defined to 11 on GCC 3.4.3, OpenSolaris 8.11
#undef EAX
#endif

/// \brief EAX block cipher mode of operation
/// \tparam T_BlockCipher block cipher
/// \details \p EAX provides the \p Encryption and \p Decryption typedef. See EAX_Base
///   and EAX_Final for the AuthenticatedSymmetricCipher implementation.
/// \sa <a href="http://www.cryptopp.com/wiki/EAX_Mode">EAX Mode</a> and
///   <A HREF="http://www.cryptopp.com/wiki/Modes_of_Operation">Modes of Operation</A>
///   on the Crypto++ wiki.
/// \since Crypto++ 5.6.0
template <class T_BlockCipher>
struct EAX : public AuthenticatedSymmetricCipherDocumentation
{
    typedef EAX_Final<T_BlockCipher, true> Encryption;
    typedef EAX_Final<T_BlockCipher, false> Decryption;
};

NAMESPACE_END

#endif