static byte[] joinDataAndKnown(final byte[] data){
  final byte[] dataAndCheck=new byte[KNOWN_VAL.length + data.length];
  System.arraycopy(KNOWN_VAL,0,dataAndCheck,0,KNOWN_VAL.length);
  System.arraycopy(data,0,dataAndCheck,KNOWN_VAL.length,data.length);
  return dataAndCheck;
}

static byte [ ] joinDataAndKnown ( final byte [ ] data ) { final byte [ ] dataAndCheck = new byte [ KNOWN_VAL . length + data . length ] ; System . arraycopy ( KNOWN_VAL , 0 , dataAndCheck , 0 , KNOWN_VAL . length ) ; System . arraycopy ( data , 0 , dataAndCheck , KNOWN_VAL . length , data . length ) ; return dataAndCheck ; }
join known and data into one array . < p > package access so we can test .
