mgf1.cpp

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/*
* MGF1
* (C) 1999-2007 Jack Lloyd
*
* Botan is released under the Simplified BSD License (see license.txt)
*/
 
#include <botan/internal/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;
 
   std::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;
      }
   }
 
}