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// hmac.h - written and placed in the public domain by Wei Dai
#ifndef CRYPTOPP_HMAC_H
#define CRYPTOPP_HMAC_H
#include "seckey.h"
#include "secblock.h"
NAMESPACE_BEGIN(CryptoPP)
template <class T>
class HMAC_Base : public VariableKeyLength<16, 0, UINT_MAX>, public MessageAuthenticationCode
{
public:
static std::string StaticAlgorithmName() {return std::string("HMAC(") + T::StaticAlgorithmName() + ")";}
// put enums here for Metrowerks 4
enum {DIGESTSIZE=T::DIGESTSIZE, BLOCKSIZE=T::BLOCKSIZE};
HMAC_Base() : m_innerHashKeyed(false) {}
void UncheckedSetKey(const byte *userKey, unsigned int keylength);
void Restart();
void Update(const byte *input, unsigned int length);
void TruncatedFinal(byte *mac, unsigned int size);
unsigned int DigestSize() const {return DIGESTSIZE;}
private:
void KeyInnerHash();
enum {IPAD=0x36, OPAD=0x5c};
FixedSizeSecBlock<byte, BLOCKSIZE> k_ipad, k_opad;
FixedSizeSecBlock<byte, DIGESTSIZE> m_innerHash;
T m_hash;
bool m_innerHashKeyed;
};
//! <a href="http://www.weidai.com/scan-mirror/mac.html#HMAC">HMAC</a>
/*! HMAC(K, text) = H(K XOR opad, H(K XOR ipad, text)) */
template <class T>
class HMAC : public MessageAuthenticationCodeTemplate<HMAC_Base<T> >
{
public:
HMAC() {}
HMAC(const byte *key, unsigned int length=HMAC_Base<T>::DEFAULT_KEYLENGTH)
{SetKey(key, length);}
};
template <class T>
void HMAC_Base<T>::UncheckedSetKey(const byte *userKey, unsigned int keylength)
{
AssertValidKeyLength(keylength);
Restart();
if (keylength <= T::BLOCKSIZE)
memcpy(k_ipad, userKey, keylength);
else
{
m_hash.CalculateDigest(k_ipad, userKey, keylength);
keylength = T::DIGESTSIZE;
}
assert(keylength <= T::BLOCKSIZE);
memset(k_ipad+keylength, 0, T::BLOCKSIZE-keylength);
for (unsigned int i=0; i<T::BLOCKSIZE; i++)
{
k_opad[i] = k_ipad[i] ^ OPAD;
k_ipad[i] ^= IPAD;
}
}
template <class T>
void HMAC_Base<T>::KeyInnerHash()
{
assert(!m_innerHashKeyed);
m_hash.Update(k_ipad, T::BLOCKSIZE);
m_innerHashKeyed = true;
}
template <class T>
void HMAC_Base<T>::Restart()
{
if (m_innerHashKeyed)
{
m_hash.Restart();
m_innerHashKeyed = false;
}
}
template <class T>
void HMAC_Base<T>::Update(const byte *input, unsigned int length)
{
if (!m_innerHashKeyed)
KeyInnerHash();
m_hash.Update(input, length);
}
template <class T>
void HMAC_Base<T>::TruncatedFinal(byte *mac, unsigned int size)
{
ThrowIfInvalidTruncatedSize(size);
if (!m_innerHashKeyed)
KeyInnerHash();
m_hash.Final(m_innerHash);
m_hash.Update(k_opad, T::BLOCKSIZE);
m_hash.Update(m_innerHash, DIGESTSIZE);
m_hash.TruncatedFinal(mac, size);
m_innerHashKeyed = false;
}
NAMESPACE_END
#endif
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