ccm.h

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// ccm.h - originally written and placed in the public domain by Wei Dai
 
/// \file ccm.h
/// \brief CCM block cipher mode of operation
/// \since Crypto++ 5.6.0
 
#ifndef CRYPTOPP_CCM_H
#define CRYPTOPP_CCM_H
 
#include "authenc.h"
#include "modes.h"
 
NAMESPACE_BEGIN(CryptoPP)
 
/// \brief CCM block cipher base implementation
/// \details Base implementation of the AuthenticatedSymmetricCipher interface
/// \since Crypto++ 5.6.0
class CRYPTOPP_DLL CRYPTOPP_NO_VTABLE CCM_Base : public AuthenticatedSymmetricCipherBase
{
public:
    CCM_Base()
        : m_digestSize(0), m_L(0), m_messageLength(0), m_aadLength(0) {}
 
    // AuthenticatedSymmetricCipher
    std::string AlgorithmName() const
        {return GetBlockCipher().AlgorithmName() + std::string("/CCM");}
    std::string AlgorithmProvider() const
        {return GetBlockCipher().AlgorithmProvider();}
    size_t MinKeyLength() const
        {return GetBlockCipher().MinKeyLength();}
    size_t MaxKeyLength() const
        {return GetBlockCipher().MaxKeyLength();}
    size_t DefaultKeyLength() const
        {return GetBlockCipher().DefaultKeyLength();}
    size_t GetValidKeyLength(size_t keylength) const
        {return GetBlockCipher().GetValidKeyLength(keylength);}
    bool IsValidKeyLength(size_t keylength) const
        {return GetBlockCipher().IsValidKeyLength(keylength);}
    unsigned int OptimalDataAlignment() const
        {return GetBlockCipher().OptimalDataAlignment();}
    IV_Requirement IVRequirement() const
        {return UNIQUE_IV;}
    unsigned int IVSize() const
        {return 8;}
    unsigned int MinIVLength() const
        {return 7;}
    unsigned int MaxIVLength() const
        {return 13;}
    unsigned int DigestSize() const
        {return m_digestSize;}
    lword MaxHeaderLength() const
        {return W64LIT(0)-1;}
    lword MaxMessageLength() const
        {return m_L<8 ? (W64LIT(1)<<(8*m_L))-1 : W64LIT(0)-1;}
    bool NeedsPrespecifiedDataLengths() const
        {return true;}
    void UncheckedSpecifyDataLengths(lword headerLength, lword messageLength, lword footerLength);
 
protected:
    // AuthenticatedSymmetricCipherBase
    bool AuthenticationIsOnPlaintext() const
        {return true;}
    unsigned int AuthenticationBlockSize() const
        {return GetBlockCipher().BlockSize();}
    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 AuthenticateLastConfidentialBlock();
    void AuthenticateLastFooterBlock(byte *mac, size_t macSize);
    SymmetricCipher & AccessSymmetricCipher() {return m_ctr;}
 
    virtual BlockCipher & AccessBlockCipher() =0;
    virtual int DefaultDigestSize() const =0;
 
    const BlockCipher & GetBlockCipher() const {return const_cast<CCM_Base *>(this)->AccessBlockCipher();}
    byte *CBC_Buffer() {return m_buffer+REQUIRED_BLOCKSIZE;}
 
    enum {REQUIRED_BLOCKSIZE = 16};
    int m_digestSize, m_L;
    word64 m_messageLength, m_aadLength;
    CTR_Mode_ExternalCipher::Encryption m_ctr;
};
 
/// \brief CCM block cipher final implementation
/// \tparam T_BlockCipher block cipher
/// \tparam T_DefaultDigestSize default digest size, in bytes
/// \tparam T_IsEncryption direction in which to operate the cipher
/// \since Crypto++ 5.6.0
template <class T_BlockCipher, int T_DefaultDigestSize, bool T_IsEncryption>
class CCM_Final : public CCM_Base
{
public:
    static std::string StaticAlgorithmName()
        {return T_BlockCipher::StaticAlgorithmName() + std::string("/CCM");}
    bool IsForwardTransformation() const
        {return T_IsEncryption;}
 
private:
    BlockCipher & AccessBlockCipher() {return m_cipher;}
    int DefaultDigestSize() const {return T_DefaultDigestSize;}
    typename T_BlockCipher::Encryption m_cipher;
};
 
/// \brief CCM block cipher mode of operation
/// \tparam T_BlockCipher block cipher
/// \tparam T_DefaultDigestSize default digest size, in bytes
/// \details \p CCM provides the \p Encryption and \p Decryption typedef. See GCM_Base
///   and GCM_Final for the AuthenticatedSymmetricCipher implementation.
/// \sa <a href="http://www.cryptopp.com/wiki/CCM_Mode">CCM 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, int T_DefaultDigestSize = 16>
struct CCM : public AuthenticatedSymmetricCipherDocumentation
{
    typedef CCM_Final<T_BlockCipher, T_DefaultDigestSize, true> Encryption;
    typedef CCM_Final<T_BlockCipher, T_DefaultDigestSize, false> Decryption;
};
 
NAMESPACE_END
 
#endif