/*

* MGF1

* (C) 1999-2007 Jack Lloyd

*

* Botan is released under the Simplified BSD License (see license.txt)

*/

#include <botan/mgf1.h>

#include <botan/hash.h>

#include <algorithm>

namespace Botan {

void mgf1_mask(HashFunction& hash,

               const uint8_t in[], size_t in_len,

               uint8_t out[], size_t out_len)

   {

   uint32_t counter = 0;

   secure_vector<uint8_t> buffer(hash.output_length());

   while(out_len)

      {

      hash.update(in, in_len);

      hash.update_be(counter);

      hash.final(buffer.data());

      const size_t xored = std::min<size_t>(buffer.size(), out_len);

      xor_buf(out, buffer.data(), xored);

      out += xored;

      out_len -= xored;

      ++counter;

      }

   }

}