34C3 Junior CTF: dotr

dotr_solve.py

#!/usr/bin/env python2
# coding: utf-8

import itertools

def decrypt(msg, k):
    m = "*" * len(msg)
    c = 0
    for i in k:
        for j in range(i, len(msg), 8):
            m = m[:j] + msg[c] + m[j+1:]
            c += 1

    return m

encrypt_txt = "03_duCbr5e_i_rY_or cou14:L4G f313_Th_etrph00 Wh03UBl_oo?n07!_e"

for k in itertools.permutations(range(8)):
    s = decrypt(decrypt(encrypt_txt, k), k)
    if "34C3" in s:
        print s