python中的xor函数

Question

I'll be happy if someone can help with XOR function in python.

for example, I have two quite big messages (about 300 symbols) that is writteb by hex code how can I XOR them properly? I tried use general functions and converted to another types, but I wasn't able to do that(

I don't know which type of data I need to convert for?

Answer 1

If I get your question correctly, if you have 2 hex numbers represented as string:

a = "e877a5e68bea88d61b93ac5ee0d562e8e9"
b = "23fe3231699ade23482"

you can xor any of them with some mask, by converting to int, and applying bitwise xor operator:

xor_result = int(a, 16) ^ int(b, 16)

print '%x' % xor_result

and, if you want to keep the original format

string_xor_result = hex(xor_result)[2:]

Answer 2

Iterate over the string chars, then convert each char to int ( int(a,16) ), then apply xor, reconvert to hex with hex , strip the leading '0x' with [2:] , and finally join everything

stra = 'abc'
strb = 'abd'
''.join(hex( int(a,16) ^ int(b,16) )[2:] for a,b in zip(stra, strb))

Note that, as pointed in the comments, it will work only if the two strings have the same length. Otherwise some chars of the longer string will be ignored.

Answer 3

If two strings do not have the same length you can add one line, cycle()

stra = raw_input("msg: ")
strb = raw_input("key: ")
strb = cycle(strb)

print ''.join(hex( int(a,16) ^ int(b,16) )[2:] for a,b in zip(stra, strb))