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