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### Re^2: strings to number and XOR

 on Oct 07, 2009 at 16:57 UTC ( #799760=note: print w/replies, xml ) Need Help??

in reply to Re: strings to number and XOR
in thread strings to number and XOR

Okay one last item. Using:\$key = "\x4f\xcb" x (length(\$msg)/2);
how do I handle odd length messages? We can see in your example too, that the last character is not xored, 0x7a. I would like it to be xored with 0x4f, or the first part of the key. Thanks for your help. Aaron

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Re^3: strings to number and XOR
by Anonymous Monk on Oct 07, 2009 at 17:01 UTC
I think I solved this. I just added 1 more, since an extra byte or two in the key doesn't hurt anything.
```\$key = "\x4f\xcb" x ((length(\$msg)/2)+1);
Aaron
an extra byte or two in the key doesn't hurt anything

It's maybe worth trimming your XORed string to the original length, or else half of your key pattern might leak... (to anyone who makes an educated guess about the procedure)

```t  h  i  s     i  s     a     t  e  s  t     m  e  s  s  a  g  e  z
74 68 69 73 20 69 73 20 61 20 74 65 73 74 20 6d 65 73 73 61 67 65 7a
4f cb 4f cb 4f cb 4f cb 4f cb 4f cb 4f cb 4f cb 4f cb 4f cb 4f cb 4f c
+b
3b a3 26 b8 6f a2 3c eb 2e eb 3b ae 3c bf 6f a6 2a b8 3c aa 28 ae 35 c
+b
^
+^

... just in case you do want to keep it secret (I don't really know what you intent to use this for).

(OTOH, if encryption was the idea, and security was of any relevance, I'd choose a different approach anyway :)

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