Crypto++
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00001 #ifndef CRYPTOPP_DMAC_H 00002 #define CRYPTOPP_DMAC_H 00003 00004 #include "cbcmac.h" 00005 00006 NAMESPACE_BEGIN(CryptoPP) 00007 00008 //! _ 00009 template <class T> 00010 class CRYPTOPP_NO_VTABLE DMAC_Base : public SameKeyLengthAs<T>, public MessageAuthenticationCode 00011 { 00012 public: 00013 static std::string StaticAlgorithmName() {return std::string("DMAC(") + T::StaticAlgorithmName() + ")";} 00014 00015 CRYPTOPP_CONSTANT(DIGESTSIZE=T::BLOCKSIZE) 00016 00017 DMAC_Base() {} 00018 00019 void UncheckedSetKey(const byte *key, unsigned int length, const NameValuePairs ¶ms); 00020 void Update(const byte *input, size_t length); 00021 void TruncatedFinal(byte *mac, size_t size); 00022 unsigned int DigestSize() const {return DIGESTSIZE;} 00023 00024 private: 00025 byte *GenerateSubKeys(const byte *key, size_t keylength); 00026 00027 size_t m_subkeylength; 00028 SecByteBlock m_subkeys; 00029 CBC_MAC<T> m_mac1; 00030 typename T::Encryption m_f2; 00031 unsigned int m_counter; 00032 }; 00033 00034 //! DMAC 00035 /*! Based on "CBC MAC for Real-Time Data Sources" by Erez Petrank 00036 and Charles Rackoff. T should be a class derived from BlockCipherDocumentation. 00037 */ 00038 template <class T> 00039 class DMAC : public MessageAuthenticationCodeFinal<DMAC_Base<T> > 00040 { 00041 public: 00042 DMAC() {} 00043 DMAC(const byte *key, size_t length=DMAC_Base<T>::DEFAULT_KEYLENGTH) 00044 {this->SetKey(key, length);} 00045 }; 00046 00047 template <class T> 00048 void DMAC_Base<T>::UncheckedSetKey(const byte *key, unsigned int length, const NameValuePairs ¶ms) 00049 { 00050 m_subkeylength = T::StaticGetValidKeyLength(T::BLOCKSIZE); 00051 m_subkeys.resize(2*UnsignedMin((unsigned int)T::BLOCKSIZE, m_subkeylength)); 00052 m_mac1.SetKey(GenerateSubKeys(key, length), m_subkeylength, params); 00053 m_f2.SetKey(m_subkeys+m_subkeys.size()/2, m_subkeylength, params); 00054 m_counter = 0; 00055 m_subkeys.resize(0); 00056 } 00057 00058 template <class T> 00059 void DMAC_Base<T>::Update(const byte *input, size_t length) 00060 { 00061 m_mac1.Update(input, length); 00062 m_counter = (unsigned int)((m_counter + length) % T::BLOCKSIZE); 00063 } 00064 00065 template <class T> 00066 void DMAC_Base<T>::TruncatedFinal(byte *mac, size_t size) 00067 { 00068 ThrowIfInvalidTruncatedSize(size); 00069 00070 byte pad[T::BLOCKSIZE]; 00071 byte padByte = byte(T::BLOCKSIZE-m_counter); 00072 memset(pad, padByte, padByte); 00073 m_mac1.Update(pad, padByte); 00074 m_mac1.TruncatedFinal(mac, size); 00075 m_f2.ProcessBlock(mac); 00076 00077 m_counter = 0; // reset for next message 00078 } 00079 00080 template <class T> 00081 byte *DMAC_Base<T>::GenerateSubKeys(const byte *key, size_t keylength) 00082 { 00083 typename T::Encryption cipher(key, keylength); 00084 memset(m_subkeys, 0, m_subkeys.size()); 00085 cipher.ProcessBlock(m_subkeys); 00086 m_subkeys[m_subkeys.size()/2 + T::BLOCKSIZE - 1] = 1; 00087 cipher.ProcessBlock(m_subkeys+m_subkeys.size()/2); 00088 return m_subkeys; 00089 } 00090 00091 NAMESPACE_END 00092 00093 #endif