Question

I have a list of XOR encrypted bytes written in hex (contained in “cipher.txt”, one byte per line) and I know that the XOR key used is one byte. Therefore I’m trying a brute force approach like this:

f = open("cipher.txt", "r")
ciphers = f.readlines()
f.close

for x in range(0, 255):
    key = bin(int(x))[2:]
    for line in ciphers:
        w = bin(int(line, 16))[2:]
        y = int(w)
        z = y ^ x
    print chr(z),
print ""

There, my results (z) don’t stay binary. Instead I get results like “10010084”.
If I don’t use the “y = int(w)” part, I get “unsupported operand type(s) for ^: ‘str’ and ‘int'” as an error, even though I don’t understand why, since the definition of the variable is similar to the “key” variable which works.

I suspect that there’s one big really stupid mistake in my code which causes it to fail.
Can anyone advise?

Answer 1

Try this:

y = int(w, base=2)

also you haven’t closed f:

f.close()

I suggest using context manager in order to manage opened files:

with open("cipher.txt", "r") as f:
    ciphers = f.readlines()