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hmac.h

00001 // hmac.h - written and placed in the public domain by Wei Dai
00002 
00003 #ifndef CRYPTOPP_HMAC_H
00004 #define CRYPTOPP_HMAC_H
00005 
00006 #include "seckey.h"
00007 #include "secblock.h"
00008 
00009 NAMESPACE_BEGIN(CryptoPP)
00010 
00011 //! _
00012 class CRYPTOPP_DLL CRYPTOPP_NO_VTABLE HMAC_Base : public VariableKeyLength<16, 0, INT_MAX>, public MessageAuthenticationCode
00013 {
00014 public:
00015     HMAC_Base() : m_innerHashKeyed(false) {}
00016     void UncheckedSetKey(const byte *userKey, unsigned int keylength, const NameValuePairs &params);
00017 
00018     void Restart();
00019     void Update(const byte *input, size_t length);
00020     void TruncatedFinal(byte *mac, size_t size);
00021     unsigned int OptimalBlockSize() const {return const_cast<HMAC_Base*>(this)->AccessHash().OptimalBlockSize();}
00022     unsigned int DigestSize() const {return const_cast<HMAC_Base*>(this)->AccessHash().DigestSize();}
00023 
00024 protected:
00025     virtual HashTransformation & AccessHash() =0;
00026     byte * AccessIpad() {return m_buf;}
00027     byte * AccessOpad() {return m_buf + AccessHash().BlockSize();}
00028     byte * AccessInnerHash() {return m_buf + 2*AccessHash().BlockSize();}
00029 
00030 private:
00031     void KeyInnerHash();
00032 
00033     SecByteBlock m_buf;
00034     bool m_innerHashKeyed;
00035 };
00036 
00037 //! <a href="http://www.weidai.com/scan-mirror/mac.html#HMAC">HMAC</a>
00038 /*! HMAC(K, text) = H(K XOR opad, H(K XOR ipad, text)) */
00039 template <class T>
00040 class HMAC : public MessageAuthenticationCodeImpl<HMAC_Base, HMAC<T> >
00041 {
00042 public:
00043     CRYPTOPP_CONSTANT(DIGESTSIZE=T::DIGESTSIZE)
00044     CRYPTOPP_CONSTANT(BLOCKSIZE=T::BLOCKSIZE)
00045 
00046     HMAC() {}
00047     HMAC(const byte *key, size_t length=HMAC_Base::DEFAULT_KEYLENGTH)
00048         {this->SetKey(key, length);}
00049 
00050     static std::string StaticAlgorithmName() {return std::string("HMAC(") + T::StaticAlgorithmName() + ")";}
00051     std::string AlgorithmName() const {return std::string("HMAC(") + m_hash.AlgorithmName() + ")";}
00052 
00053 private:
00054     HashTransformation & AccessHash() {return m_hash;}
00055 
00056     T m_hash;
00057 };
00058 
00059 NAMESPACE_END
00060 
00061 #endif

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