Tokyo Westerns / MMA 2nd 2016 - Make a palindrome!

Your task is to make a palindrome string by rearranging and concatenating given words.

Input Format: N ... Answer Format: Rearranged words separated by space. Each words contain only lower case alphabet characters.

Example Input: 3 ab cba c Example Answer: ab c cba

You have to connect to ppc1.chal.ctf.westerns.tokyo:31111(TCP) to answer the problem.

$ nc ppc1.chal.ctf.westerns.tokyo 31111

• Time limit is 3 minutes.
• The maximum number of words is 10.
• There are 30 cases. You can get flag 1 on case 1. You can get flag 2 on case 30.
• samples.7z Server connection examples.

We used pwntools to solve it even though the organizers gave a code for connecting with the server (?). No way we should use it :)

from pwn import *
import itertools

def rearrange(words):
    combinations = itertools.permutations(words)
    return combinations

def checkPal(combinations):
    for comb in combinations:
       possiblePal = ''.join(comb)
       if possiblePal==possiblePal[::-1]:
           possiblePal[::-1] 
           pal = ' '.join(comb)
           return pal 
   
r = remote('ppc1.chal.ctf.westerns.tokyo', 31111)
r.recvuntil('play!')

i=1
while i<31:
    print(r.recvuntil('Input: '))

    inputStr = r.recvuntil('\n')
    words = inputStr.split()
    words.pop(0)
    combinations = rearrange(words)
    pal = checkPal(combinations)
    print(pal)
    r.sendline(pal)
    i = i+1 

print(r.recvline())
r.close()

FLAG 1: TWCTF{Charisma_School_Captain}
FLAG 2: TWCTF{Hiyokko_Tsuppari}