Cryptography - HW1.2 (Challenge-02)

def fixed_xor(s1, s2):
    res = ''

    for i in range(len(s1)):
        # # convert hex numbers to decimal
        i1, i2 = int(s1[i], 16), int(s2[i], 16)

        # evaluate xor product
        xor = i1 ^ i2

        # convert decimal back to hex
        xor_s = hex(xor)

        # remove '0x' in the beginning of the string
        xor_s = xor_s[2:]

        # append to result
        res += xor_s

    return res


if __name__ == "__main__":
    s1 = input()
    s2 = input()
    result = fixed_xor(s1, s2)
    print(result)