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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 class CRYPTOPP_DLL HMAC_Base : public VariableKeyLength<16, 0, UINT_MAX>, public MessageAuthenticationCode
00012 {
00013 public:
00014         HMAC_Base() : m_innerHashKeyed(false) {}
00015         void UncheckedSetKey(const byte *userKey, unsigned int keylength);
00016 
00017         void Restart();
00018         void Update(const byte *input, unsigned int length);
00019         void TruncatedFinal(byte *mac, unsigned int size);
00020         unsigned int OptimalBlockSize() const {return const_cast<HMAC_Base*>(this)->AccessHash().OptimalBlockSize();}
00021         unsigned int DigestSize() const {return const_cast<HMAC_Base*>(this)->AccessHash().DigestSize();}
00022 
00023 protected:
00024         virtual HashTransformation & AccessHash() =0;
00025         virtual byte * AccessIpad() =0;
00026         virtual byte * AccessOpad() =0;
00027         virtual byte * AccessInnerHash() =0;
00028 
00029 private:
00030         void KeyInnerHash();
00031 
00032         enum {IPAD=0x36, OPAD=0x5c};
00033 
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 MessageAuthenticationCodeFinalTemplate<HMAC_Base, HMAC<T> >
00041 {
00042 public:
00043         enum {DIGESTSIZE=T::DIGESTSIZE, BLOCKSIZE=T::BLOCKSIZE};
00044 
00045         HMAC() {}
00046         HMAC(const byte *key, unsigned int length=HMAC_Base::DEFAULT_KEYLENGTH)
00047                 {SetKey(key, length);}
00048 
00049         static std::string StaticAlgorithmName() {return std::string("HMAC(") + T::StaticAlgorithmName() + ")";}
00050 
00051 private:
00052         HashTransformation & AccessHash() {return m_hash;}
00053         byte * AccessIpad() {return m_ipad;}
00054         byte * AccessOpad() {return m_opad;}
00055         byte * AccessInnerHash() {return m_innerHash;}
00056 
00057         FixedSizeSecBlock<byte, BLOCKSIZE> m_ipad, m_opad;
00058         FixedSizeSecBlock<byte, DIGESTSIZE> m_innerHash;
00059         T m_hash;
00060 };
00061 
00062 NAMESPACE_END
00063 
00064 #endif

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