def _encrypted_data_header_v2(salt, iter_mag)
      "\x02" + salt.bytes.length.chr + [iter_mag].pack('c') + salt
    end
def _encrypted_data_header_v2(salt, iter_mag)
      "\x02" + salt.bytes.length.chr + [iter_mag].pack('c') + salt
    end
Generates the version 2 encrypted data header:
 |     Byte 0     |     Byte 1     |         Byte 2       | Bytes 3...S
 ----------------------------------------------------------------------
 |    Version     |   Salt Length  |  Iteration Magnitude |    Salt