Python XOR bytes

You can use single bytes or multiple-byte keys for XOR in Python, and use looping to test keys. Here’s the XOR truth table.

• 0 ^ 0 = 0
• 0 ^ 1 = 1
• 1 ^ 0 = 1
• 1 ^ 1 = 0

XOR operates one bit at a time. Python indicates XOR with the ^ operator.

Python XOR bytes

Simple example code XOR 2 bytes objects.

def bxor(b1, b2): # use xor for bytes
    result = b""
    for b1, b2 in zip(b1, b2):
        result += bytes([b1 ^ b2])
    return result

Alternatively, you can use a bytearray which is mutable and can therefore avoid the problem. It also allows you to not allocate a new bytes object on every iteration, you can just append the byte/int.

def bxor(b1, b2): # use xor for bytes
    result = bytearray()
    for b1, b2 in zip(b1, b2):
        result.append(b1 ^ b2)
    return result

If you want something faster than the “manual” methods given, there’s always Numpy:

import numpy

def bxor_numpy(b1, b2):
    n_b1 = numpy.fromstring(b1, dtype='uint8')
    n_b2 = numpy.fromstring(b2, dtype='uint8')

    return (n_b1 ^ n_b2).tostring()

A quick timeit comparison:

import timeit


def bxor_ba(b1, b2):
    result = bytearray(b1)
    for i, b in enumerate(b2):
        result[i] ^= b
    return bytes(result)


def bxor(b1, b2):  # use xor for bytes
    result = b""
    for b1, b2 in zip(b1, b2):
        result += bytes([b1 ^ b2])
    return result


b1, b2 = b'abcdefg' * 10, b'aaaaaaa' * 10
print(timeit.timeit('it(b1, b2)', 'from __main__ import b1, b2, bxor as it', number=10000))
print(timeit.timeit('it(b1, b2)', 'from __main__ import b1, b2, bxor_ba as it', number=10000))

Output:

Do comment if you have any doubts or suggestions on this Python XOR topic.

Note: IDE: PyCharm 2021.3.3 (Community Edition)

Windows 10

Python 3.10.1

All Python Examples are in Python 3, so Maybe its different from python 2 or upgraded versions.