CODEWITHSUNDEEP
python-3.xformatbytexor
Ursa Major
Ursa Major

Reputation: 901

XOR bytes in Python3

On trying to xor bytes in python3:

import os,binascii
import numpy as np

def xor_byte_hex_strings(a, b) :
    return bytes(x ^ y for x, y in zip(a, b))


number_of_bytes = 2

random_bytes = []

random_bytes_str = binascii.b2a_hex(os.urandom(number_of_bytes))
random_bytes.append(random_bytes_str)

print(random_bytes_str)
print(bytearray(random_bytes_str))

random_bytes_str = binascii.b2a_hex(os.urandom(number_of_bytes))
random_bytes.append(random_bytes_str)

resultant = xor_byte_hex_strings(random_bytes[0], random_bytes[1])
print("resultant = ", bytearray(resultant))
print(random_bytes)

resultant = xor_byte_hex_strings(random_bytes[1], resultant)
print(resultant)

The result is b'\x03\x03\x0cU' instead of b'13ce. How do we convert the format from b'\x03\x03\x0cU' to b'13ce?

Upvotes: 1

Views: 3757

Answers (1)

Error - Syntactical Remorse
Error - Syntactical Remorse

Reputation: 7887

Why not work with strings and ints to make your life easier?

import os,binascii

def xor_strings(a, b):
    result = int(a, 16) ^ int(b, 16) # convert to integers and xor them together
    return '{:x}'.format(result)     # convert back to hexadecimal

number_of_bytes = 2
random_bytes = []

# decode() to turn it into a str.
random_bytes_str = binascii.b2a_hex(os.urandom(number_of_bytes)).decode()
random_bytes.append(random_bytes_str)


random_bytes_str = binascii.b2a_hex(os.urandom(number_of_bytes)).decode()
random_bytes.append(random_bytes_str)

print(random_bytes)
xored = xor_strings(*random_bytes)
print("resultant = ", xored.encode())

print([random_bytes[1], xored])
resultant = xor_strings(random_bytes[1], xored)
print(resultant.encode()) # encode() will turn it back to bytes if you want bytes

Output:

['4588', '3af9']
resultant =  b'7f71'
['3af9', '7f71']
b'4588'

Upvotes: 1

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