Fastest bitwise xor between two multibyte binary data variables

Question

What is the fastest way to implementat the following logic:

def xor(data, key):
    l = len(key)

    buff = \"\"
    for i in range(0, len(data)):
        b         


        

Answer 1

Not tested

Don't know if it's faster

supposing that len(mystring) is a multiple of 4

def xor(hash,mystring):
    s = struct.Struct("