Question

So I have a problem where I want to xor various hex strings, convert them to regular english strings, then re-convert them to hex strings. I’m not really familiar with working with hex or xor in any meaningful way, however. Do I need to convert the hex to binary or unicode before I perform a bitwise xor operation? If so, how do I retrieve the hex values once that is done? I’ve been looking into using str.encode(‘hex’) and str.decode(‘hex’), but I keep getting errors saying that I am using non-hexadecimal characters. In short, I’m totally lost.

Answer 1

Python has an XOR operator for integers: ^. Here’s how you could use it:

>>> hex(int("123abc", 16) ^ int("def456", 16))
'0xccceea'

EDIT: testing with long hex strings as per your comment:

>>> def hexor(hex1, hex2):
...     """XOR two hex strings."""
...     xor = hex(int(hex1, 16) ^ int(hex2, 16))
...     return xor[2:].rstrip("L")  # get rid of "0x" and maybe "L"
... 
>>> import random
>>> a = "".join(random.choice("0123456789abcdef") for i in range(200))
>>> b = "".join(random.choice("0123456789abcdef") for i in range(200))
>>> a
'8db12de2f49f092620f6d79d6601618daab5ec6747266c2eea29c3493278daf82919aae6a72
64d4cf3dffd70cb1b6fde72ba2a04ac354fcb871eb60e088c2167e73006e0275287de6fc6133
56e44d7b0ff8378a0830d9d87151cbf3331382b096f02fd72'
>>> b
'40afe17fa8fbc56153c78f504e50a241df0a35fd204f8190c0591eda9c63502b41611aa9ac2
27fcd1a9faea642d89a3a212885711d024d2c973115eea11ceb6a57a6fa1f478998b94aa7d3e
993c04d24a0e1ac7c10fd834de61caefb97bcb65605f06eae'
>>> hexor(a, b)
'cd1ecc9d5c64cc47733158cd2851c3cc75bfd99a6769edbe2a70dd93ae1b8ad36878b04f0b0
43281e94053d689c3f5e45392af75b13702e7102fa3e0a990ca0db096fcff60db1f672561c0d
cfd849a945f62d4dc93f01ecaf30011c8a6849d5f6af293dc'