CODEWITHSUNDEEP
pythonencryption
PAH
PAH

Reputation: 5

XOR strings of bytes

I want to XOR two strings of bytes and I'm trying to figure out what is the difference between these two pieces of code, the last one works, but I dont understand why one does and the other doesn't. I've also tried with bytes object but doesn't work either.

    resultado3 = bytearray(len(ab))
    for byte1, byte2 in zip(ab, bb):
      resultado3 += bytearray(byte1 ^ byte2)

    resultado2 = bytes([ x^y for (x,y) in zip(ab, bb)])

Being my two inputs: ab = 1c0111001f010100061a024b53535009181c and bb = 686974207468652062756c6c277320657965 and the outputs when I print them: resultado2 = b"the kid don't play" and resultado3 = bytearray(b'\x00 ..... \x00') (all filled with zeros)

Upvotes: 0

Views: 350

Answers (1)

Mia
Mia

Reputation: 2676

The reason is simple: bytearray(n) returns a zero-initialized bytearray of length n. So when you did resultado3 += bytearray(byte1 ^ byte2) you are effectively concatenating all-null bytearray of some length to your resultado3.

To achieve your intended purpose, use resultado3 += bytearray([byte1 ^ byte2]) instead (note the list of one element).

Upvotes: 1

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