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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, UINT_MAX>, public MessageAuthenticationCode
00013 {
00014 public:
00015         HMAC_Base() : m_innerHashKeyed(false) {}
00016         void UncheckedSetKey(const byte *userKey, unsigned int keylength);
00017 
00018         void Restart();
00019         void Update(const byte *input, unsigned int length);
00020         void TruncatedFinal(byte *mac, unsigned int 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         virtual byte * AccessIpad() =0;
00027         virtual byte * AccessOpad() =0;
00028         virtual byte * AccessInnerHash() =0;
00029 
00030 private:
00031         void KeyInnerHash();
00032 
00033         enum {IPAD=0x36, OPAD=0x5c};
00034 
00035         bool m_innerHashKeyed;
00036 };
00037 
00038 //! <a href="http://www.weidai.com/scan-mirror/mac.html#HMAC">HMAC</a>
00039 /*! HMAC(K, text) = H(K XOR opad, H(K XOR ipad, text)) */
00040 template <class T>
00041 class HMAC : public MessageAuthenticationCodeImpl<HMAC_Base, HMAC<T> >
00042 {
00043 public:
00044         enum {DIGESTSIZE=T::DIGESTSIZE, BLOCKSIZE=T::BLOCKSIZE};
00045 
00046         HMAC() {}
00047         HMAC(const byte *key, unsigned int 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         byte * AccessIpad() {return m_ipad;}
00056         byte * AccessOpad() {return m_opad;}
00057         byte * AccessInnerHash() {return m_innerHash;}
00058 
00059         FixedSizeSecBlock<byte, BLOCKSIZE> m_ipad, m_opad;
00060         FixedSizeSecBlock<byte, DIGESTSIZE> m_innerHash;
00061         T m_hash;
00062 };
00063 
00064 NAMESPACE_END
00065 
00066 #endif

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