standard: (default) Binary safe
      pads with the number of bytes that should be truncated. So, if 
      blocksize is 8, then "0A0B0C" will be padded with "05", resulting
      in "0A0B0C0505050505". If the final block is a full block of 8 
      bytes, then a whole block of "0808080808080808" is appended.

   oneandzeroes: Binary safe
      pads with "80" followed by as many "00" necessary to fill the
      block. If the last block is a full block and blocksize is 8, a
      block of "8000000000000000" will be appended.

   null: text only
      pads with as many "00" necessary to fill the block. If the last 
      block is a full block and blocksize is 8, a block of 
      "0000000000000000" will be appended.

   space: text only
      same as "null", but with "20".