Author 
Message 
zero0cripton
Joined: 21 Jan 2010 Posts: 6 Location: Portugal 

Didactic XOR Cipher 

is there any chance that the site is not working well? i think that i have figured out the answer and still it won't let me go through. Can anyone send me the answer on a PM or just give me some tips on this?
_________________ Sex is like hacking, you get in, you get out and you hope you didn't leave anything behind that can be traced back to you. 

Sun Jan 24, 2010 6:52 pm 


yushun
Joined: 08 Apr 2010 Posts: 1




remember the base format


Sun Apr 11, 2010 9:43 pm 


Masti6
Joined: 15 May 2010 Posts: 55 Location: Finland, Nurmes 



I don't get this one.
XOR is something between AND and OR, right? Then how do I XOR something. I can't just OR / AND something into something else can I?
I'm so damn confused.
Someone explain the basic trick for XOR'ing(?) so I could figure it out myself. Thanks in advance.


Sat May 15, 2010 3:40 pm 


CodeX
Joined: 17 Oct 2008 Posts: 350




If you don't understand something you really should resarch


Sat May 15, 2010 4:02 pm 


Masti6
Joined: 15 May 2010 Posts: 55 Location: Finland, Nurmes 



Oh I've done my Researches. I just can't figure out how to use it in this example.
Some enlightening tips are appreciated. But thanks for the additional link to a page of what kind of I've seen too many so far. (< If that made any sense...)


Sat May 15, 2010 4:45 pm 


CodeX
Joined: 17 Oct 2008 Posts: 350




If you get both AND & OR then here's a breakdown with truth tables:
AND
0 0 → 0
0 1 → 0
1 0 → 0
1 1 → 1
OR
0 0 → 0
0 1 → 1
1 0 → 1
1 1 → 1
NOT
0 → 1
1 → 0
XOR
0 0 → 0
0 1 → 1
1 0 → 1
1 1 → 0
so in terms of AND, OR & NOT you'll find XOR can be expressed as (a OR b) AND (NOT(a AND b)) which is (a  b) & (~(a & b)) in C like languages, in these you're better off just using ^ though as that's the XOR operator. These operations are usually applied to strings of bits which turns out like:


a = 10100
b = 01110
a^b = 11010 
Was that something more like that you wanted?


Sat May 15, 2010 5:29 pm 


Masti6
Joined: 15 May 2010 Posts: 55 Location: Finland, Nurmes 



I'm still working on the challenge, but thanks for an excellent and simplified tip (The Wikipedia article was horribly confusing).
I shall try bringing everything down to the binary level and trying to Decipher the code with that.
Thanks again!


Sat May 15, 2010 6:52 pm 


erry
Joined: 11 Dec 2010 Posts: 13




i did it, but it gave me a answer that isn't correct.
I took the number in HEX and turned into binary, than i XORed 79 (converted in binary too) at every number, then i put them together, but it's wrong...


Tue Apr 12, 2011 5:08 pm 


M4xZ3r0
Joined: 31 Mar 2011 Posts: 5






i did it, but it gave me a answer that isn't correct.
I took the number in HEX and turned into binary, than i XORed 79 (converted in binary too) at every number, then i put them together, but it's wrong... 


79 (decimal) 
means it is decimal already.


Wed Apr 13, 2011 9:22 am 


erry
Joined: 11 Dec 2010 Posts: 13




I know it's decimal, but i need to make him binary to XOR it


Wed Apr 13, 2011 12:19 pm 


Karian
Joined: 09 Jan 2008 Posts: 75




For me, it is not really clear what you tried exactly.
What do you mean exactly with the every number and the put them together parts of your sentence? It is unclear what you have done exactly, and that makes it difficult to pinpoint the problem.


Wed Apr 13, 2011 1:03 pm 


erry
Joined: 11 Dec 2010 Posts: 13




Well, i took the number given in HEX and i copied it in MS.Word.
After every number (or letter, because it's hexadecimal) i clicked Enter.
Then i changed every number (or letter blabla) to his value in binary. After that a XORed every binary number with 79.
I do an example hoping to not spoiler too much.
the number started with 3, so i XORed 0000011 with 1001111 (it's 79, in binary), and i obtained 1001100. I did it with every number but now i don't know how to proceed


Wed Apr 13, 2011 1:15 pm 


M4xZ3r0
Joined: 31 Mar 2011 Posts: 5






Well, i took the number given in HEX and i copied it in MS.Word.
After every number (or letter, because it's hexadecimal) i clicked Enter.
Then i changed every number (or letter blabla) to his value in binary. After that a XORed every binary number with 79.
I do an example hoping to not spoiler too much.
the number started with 3, so i XORed 0000011 with 1001111 (it's 79, in binary), and i obtained 1001100. I did it with every number but now i don't know how to proceed 
In Decimal one Byte is one Character (or 2 or 3 ^^), in Hex one Character isn't one Byte.


Wed Apr 13, 2011 3:18 pm 


thewino
Joined: 06 Apr 2011 Posts: 5




am i on the right track? hex to bin bytes xor backwards with 79 bin back to hex. this is not working for me. unless my calculations were wrong somewhere. ascii table needed perhaps?


Fri Apr 15, 2011 4:42 am 


M4xZ3r0
Joined: 31 Mar 2011 Posts: 5






am i on the right track? hex to bin bytes xor backwards with 79 bin back to hex. this is not working for me. unless my calculations were wrong somewhere. ascii table needed perhaps? 
I don't exactly know what you mean with "xor backwards" but it sounds like you're very close


Fri Apr 15, 2011 8:02 pm 


