ccm.h

Go to the documentation of this file.

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


#ifndef CRYPTOPP_CCM_H
#define CRYPTOPP_CCM_H

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

NAMESPACE_BEGIN(CryptoPP)

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");}
        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;
};

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;
};

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