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/*
Copyright (c) 2000, 2012, Oracle and/or its affiliates. All rights reserved.
This program is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation; version 2 of the License.
This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.
You should have received a copy of the GNU General Public License
along with this program; see the file COPYING. If not, write to the
Free Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston,
MA 02110-1301 USA.
*/
/* hamc.hpp implements HMAC, see RFC 2104
*/
#ifndef TAO_CRYPT_HMAC_HPP
#define TAO_CRYPT_HMAC_HPP
#include "hash.hpp"
namespace TaoCrypt {
// HMAC class template
template <class T>
class HMAC {
public:
enum { IPAD = 0x36, OPAD = 0x5C };
HMAC() : ipad_(reinterpret_cast<byte*>(&ip_)),
opad_(reinterpret_cast<byte*>(&op_)),
innerHash_(reinterpret_cast<byte*>(&innerH_))
{
Init();
}
void Update(const byte*, word32);
void Final(byte*);
void Init();
void SetKey(const byte*, word32);
private:
byte* ipad_;
byte* opad_;
byte* innerHash_;
bool innerHashKeyed_;
T mac_;
// MSVC 6 HACK, gives compiler error if calculated in array
enum { HMAC_BSIZE = T::BLOCK_SIZE / sizeof(word32),
HMAC_DSIZE = T::DIGEST_SIZE / sizeof(word32) };
word32 ip_[HMAC_BSIZE]; // align ipad_ on word32
word32 op_[HMAC_BSIZE]; // align opad_ on word32
word32 innerH_[HMAC_DSIZE]; // align innerHash_ on word32
void KeyInnerHash();
HMAC(const HMAC&);
HMAC& operator= (const HMAC&);
};
// Setup
template <class T>
void HMAC<T>::Init()
{
mac_.Init();
innerHashKeyed_ = false;
}
// Key generation
template <class T>
void HMAC<T>::SetKey(const byte* key, word32 length)
{
Init();
if (length <= T::BLOCK_SIZE)
memcpy(ipad_, key, length);
else {
mac_.Update(key, length);
mac_.Final(ipad_);
length = T::DIGEST_SIZE;
}
memset(ipad_ + length, 0, T::BLOCK_SIZE - length);
for (word32 i = 0; i < T::BLOCK_SIZE; i++) {
opad_[i] = ipad_[i] ^ OPAD;
ipad_[i] ^= IPAD;
}
}
// Inner Key Hash
template <class T>
void HMAC<T>::KeyInnerHash()
{
mac_.Update(ipad_, T::BLOCK_SIZE);
innerHashKeyed_ = true;
}
// Update
template <class T>
void HMAC<T>::Update(const byte* msg, word32 length)
{
if (!innerHashKeyed_)
KeyInnerHash();
mac_.Update(msg, length);
}
// Final
template <class T>
void HMAC<T>::Final(byte* hash)
{
if (!innerHashKeyed_)
KeyInnerHash();
mac_.Final(innerHash_);
mac_.Update(opad_, T::BLOCK_SIZE);
mac_.Update(innerHash_, T::DIGEST_SIZE);
mac_.Final(hash);
innerHashKeyed_ = false;
}
} // namespace
#endif // TAO_CRYPT_HMAC_HPP
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