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// gcm.h - written and placed in the public domain by Wei Dai
//! \file gcm.h
//! \brief GCM block cipher mode of operation
#ifndef CRYPTOPP_GCM_H
#define CRYPTOPP_GCM_H
#include "authenc.h"
#include "modes.h"
NAMESPACE_BEGIN(CryptoPP)
//! \enum GCM_TablesOption
//! \brief GCM table size options
enum GCM_TablesOption {
//! \brief Use a table with 2K entries
GCM_2K_Tables,
//! \brief Use a table with 64K entries
GCM_64K_Tables};
//! \class GCM_Base
//! \brief GCM block cipher base implementation
//! \details Base implementation of the AuthenticatedSymmetricCipher interface
class CRYPTOPP_DLL CRYPTOPP_NO_VTABLE GCM_Base : public AuthenticatedSymmetricCipherBase
{
public:
// AuthenticatedSymmetricCipher
std::string AlgorithmName() const
{return GetBlockCipher().AlgorithmName() + std::string("/GCM");}
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 n) const
{return GetBlockCipher().GetValidKeyLength(n);}
bool IsValidKeyLength(size_t n) const
{return GetBlockCipher().IsValidKeyLength(n);}
unsigned int OptimalDataAlignment() const;
IV_Requirement IVRequirement() const
{return UNIQUE_IV;}
unsigned int IVSize() const
{return 12;}
unsigned int MinIVLength() const
{return 1;}
unsigned int MaxIVLength() const
{return UINT_MAX;} // (W64LIT(1)<<61)-1 in the standard
unsigned int DigestSize() const
{return 16;}
lword MaxHeaderLength() const
{return (W64LIT(1)<<61)-1;}
lword MaxMessageLength() const
{return ((W64LIT(1)<<39)-256)/8;}
protected:
// AuthenticatedSymmetricCipherBase
bool AuthenticationIsOnPlaintext() const
{return false;}
unsigned int AuthenticationBlockSize() const
{return HASH_BLOCKSIZE;}
void SetKeyWithoutResync(const byte *userKey, size_t keylength, const NameValuePairs ¶ms);
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 GCM_TablesOption GetTablesOption() const =0;
const BlockCipher & GetBlockCipher() const {return const_cast<GCM_Base *>(this)->AccessBlockCipher();};
byte *HashBuffer() {return m_buffer+REQUIRED_BLOCKSIZE;}
byte *HashKey() {return m_buffer+2*REQUIRED_BLOCKSIZE;}
byte *MulTable() {return m_buffer+3*REQUIRED_BLOCKSIZE;}
inline void ReverseHashBufferIfNeeded();
class CRYPTOPP_DLL GCTR : public CTR_Mode_ExternalCipher::Encryption
{
protected:
void IncrementCounterBy256();
};
GCTR m_ctr;
static word16 s_reductionTable[256];
static volatile bool s_reductionTableInitialized;
enum {REQUIRED_BLOCKSIZE = 16, HASH_BLOCKSIZE = 16};
};
//! \class GCM_Final
//! \brief GCM block cipher final implementation
//! \tparam T_BlockCipher block cipher
//! \tparam T_TablesOption table size, either \p GCM_2K_Tables or \p GCM_64K_Tables
//! \tparam T_IsEncryption direction in which to operate the cipher
template <class T_BlockCipher, GCM_TablesOption T_TablesOption, bool T_IsEncryption>
class GCM_Final : public GCM_Base
{
public:
static std::string StaticAlgorithmName()
{return T_BlockCipher::StaticAlgorithmName() + std::string("/GCM");}
bool IsForwardTransformation() const
{return T_IsEncryption;}
private:
GCM_TablesOption GetTablesOption() const {return T_TablesOption;}
BlockCipher & AccessBlockCipher() {return m_cipher;}
typename T_BlockCipher::Encryption m_cipher;
};
//! \class GCM
//! \brief GCM block cipher mode of operation
//! \tparam T_BlockCipher block cipher
//! \tparam T_TablesOption table size, either \p GCM_2K_Tables or \p GCM_64K_Tables
//! \details \p GCM provides the \p Encryption and \p Decryption typedef. See GCM_Base
//! and GCM_Final for the AuthenticatedSymmetricCipher implementation.
//! \sa <a href="http://www.cryptolounge.org/wiki/GCM">GCM</a> at the Crypto Lounge
template <class T_BlockCipher, GCM_TablesOption T_TablesOption=GCM_2K_Tables>
struct GCM : public AuthenticatedSymmetricCipherDocumentation
{
typedef GCM_Final<T_BlockCipher, T_TablesOption, true> Encryption;
typedef GCM_Final<T_BlockCipher, T_TablesOption, false> Decryption;
};
NAMESPACE_END
#endif
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