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
00035
00036
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;
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