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Java Forum / General / February 2006How can you xor ArrayLists?
Can you xor Arraylist together? by using the ^ notation. I know the ^ is for integer representation so if i type cast it to Arraylist would that be sufficient? Thank you > Can you xor Arraylist together? by using the ^ notation. I know the ^ > is for integer representation so if i type cast it to Arraylist would > that be sufficient? What would be the expected output of XORing two ArrayLists? robert What would be the expected output of XORing two ArrayLists? basically i'm implementing WEP dictionary attack for school. And I had to store all possible key stream in a hash table and a hash table on take in type Object so my keystream were inputted into an Array List. I'm going to have my plaint text and convert it to bytes and place that into an array list. and then xor both together in order to retrieve the cipher text. > basically i'm implementing WEP dictionary attack for school. If you are doing anything compute -intensive with collections of primitive types (int, byte, etc) then you'd be /far/ better off putting the data into a normal int[] or byte[] array. > and then xor both together in order to > retrieve the cipher text. There's no built-in method of computing the elementwise XOR of two ArrayLists, nor of doing the same with two byte[] arrays. You'll have to code it yourself with a loop. -- chris Actually, Why couldn't he do this: BigInteger entry1 = new BigInteger(someByteArrayFromKey) BigInteger entry2 = new BigInteger(someByteArrayFromOtherKey); BigInteger newEntry = entry1.xor(entry2); Jobs done and he can use keys of any size Christian http://christian.bongiorno.org/resume.pdf > BigInteger entry1 = new BigInteger(someByteArrayFromKey) > BigInteger entry2 = new BigInteger(someByteArrayFromOtherKey); > > BigInteger newEntry = entry1.xor(entry2); That's a neat idea. You would have to be careful about the possibility of leading[*] zeros in the data. You could keep track of the size of the input arrays, and ensure that the output array is copied and shifted (if necessary) to be the same size as the inputs. Another idea would be to force the inputs to have 0x01 and 0x02 in position 0, computing the real xor for that position separately, and then stuff that into position 0 of the result. Overall, sadly, I think it's probably easier to use a loop. -- chris Yeah, that's true. In an academic setting like his it won't matter. One way of doing this would be to override xor() to assure the proper bit maintenance. There is also BitSet -- but it doesn't take a convenient byte[] input. >Can you xor Arraylist together? by using the ^ notation. I know the ^ >is for integer representation so if i type cast it to Arraylist would >that be sufficient? see the SortedArrayList class that allows various merging operations. See http://mindprod.com/products1.html#SORTEDARRAYLIST this is not APL, Operators work only on primitives.  SignatureCanadian Mind Products, Roedy Green. http://mindprod.com Java custom programming, consulting and coaching. Free MagazinesGet these publications absolutely FREE for up to 12 months. There are no hidden fees and no obligation. Simply choose a title, complete the application form and submit it. Read more ...
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