kdf2.cpp

Go to the documentation of this file.

/*
* KDF2
* (C) 1999-2007 Jack Lloyd
*
* Distributed under the terms of the Botan license
*/
 
#include <botan/kdf2.h>
 
namespace Botan {
 
/*
* KDF2 Key Derivation Mechanism
*/
SecureVector<byte> KDF2::derive(size_t out_len,
                                const byte secret[], size_t secret_len,
                                const byte P[], size_t P_len) const
   {
   SecureVector<byte> output;
   u32bit counter = 1;
 
   while(out_len && counter)
      {
      hash->update(secret, secret_len);
      hash->update_be(counter);
      hash->update(P, P_len);
 
      SecureVector<byte> hash_result = hash->final();
 
      size_t added = std::min(hash_result.size(), out_len);
      output += std::make_pair(&hash_result[0], added);
      out_len -= added;
 
      ++counter;
      }
 
   return output;
   }
 
}