Possibility to weaken AES key as Mark asked

      ptr= rkey;  /*  Just loop over tmp_key until we used all key */

    *ptr^= *sptr;

  }

#ifdef AES_USE_KEY_BITS

  /*

   This block is intended to allow more weak encryption if application 

   build with libmysqld needs to correspond to export regulations

   It should be never used in normal distribution as does not give 

   any speed improvement.

   To get worse security define AES_USE_KEY_BITS to number of bits

   you want key to be. It should be divisible by 8

   WARNING: Changing this value results in changing of enryption for 

   all key lengths  so altering this value will result in impossibility

   to decrypt data encrypted with previous value       

  */

#define AES_USE_KEY_BYTES (AES_USE_KEY_BITS/8)

  /*

   To get weaker key we use first AES_USE_KEY_BYTES bytes of created key 

   and cyclically copy them until we created all required key length

  */  

  for (ptr= rkey+AES_USE_KEY_BYTES, sptr=rkey ; ptr < rkey_end; 

       ptr++,sptr++)

  {

    if (sptr == rkey+AES_USE_KEY_BYTES)

      sptr=rkey;

    *ptr=*sptr;   

  }      

#endif

  if (direction == AES_DECRYPT)

     aes_key->nr = rijndaelKeySetupDec(aes_key->rk, rkey, AES_KEY_LENGTH);

  else