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/* pwdbased.hpp
*
* Copyright (C) 2003 Sawtooth Consulting Ltd.
*
* This file is part of yaSSL.
*
* yaSSL 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; either version 2 of the License, or
* (at your option) any later version.
*
* There are special exceptions to the terms and conditions of the GPL as it
* is applied to yaSSL. View the full text of the exception in the file
* FLOSS-EXCEPTIONS in the directory of this software distribution.
*
* yaSSL 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; if not, write to the Free Software
* Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA
*/
/* pwdbased.hpp defines PBKDF2 from PKCS #5
*/
#ifndef TAO_CRYPT_PWDBASED_HPP
#define TAO_CRYPT_PWDBASED_HPP
#include <string.h>
#include "misc.hpp"
#include "block.hpp"
#include "hmac.hpp"
namespace TaoCrypt {
// From PKCS #5, T must be type suitable for HMAC<T>
template <class T>
class PBKDF2_HMAC {
public:
word32 MaxDerivedKeyLength() const { return 0xFFFFFFFFU;} // avoid overflow
word32 DeriveKey(byte* derived, word32 dLen, const byte* pwd, word32 pLen,
const byte* salt, word32 sLen, word32 iterations) const;
};
template <class T>
word32 PBKDF2_HMAC<T>::DeriveKey(byte* derived, word32 dLen, const byte* pwd,
word32 pLen, const byte* salt, word32 sLen,
word32 iterations) const
{
assert(dLen <= MaxDerivedKeyLength());
assert(iterations > 0);
ByteBlock buffer(T::DIGEST_SIZE);
HMAC<T> hmac;
hmac.SetKey(pwd, pLen);
word32 i = 1;
while (dLen > 0) {
hmac.Update(salt, sLen);
word32 j;
for (j = 0; j < 4; j++) {
byte b = i >> ((3-j)*8);
hmac.Update(&b, 1);
}
hmac.Final(buffer.get_buffer());
word32 segmentLen = min(dLen, buffer.size());
memcpy(derived, buffer.get_buffer(), segmentLen);
for (j = 1; j < iterations; j++) {
hmac.Update(buffer.get_buffer(), buffer.size());
hmac.Final(buffer.get_buffer());
xorbuf(derived, buffer.get_buffer(), segmentLen);
}
derived += segmentLen;
dLen -= segmentLen;
i++;
}
return iterations;
}
} // naemspace
#endif // TAO_CRYPT_PWDBASED_HPP
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