question: public static Key distance ( Key a , Key b ) { Key x = new Key ( ) ; for ( int i = 0 ; i < a . hash . length ; i ++ ) { x . hash [ i ] = ( byte ) ( a . hash [ i ] ^ b . hash [ i ] ) ; } return x ; }
target:  Calculates the distance between two Keys. The distance is basically a XOR of both key hashes.