CSAW - Gotta Decrypt Them All [crypto]

pokemon_names.py

#!/usr/bin/env python3

__authors__ = ['blast_o', 'jartigag']

import base64
import os
import sys
from pwn import *
import time

morseAlphabet = {'A': '.-',  'B': '-...','C': '-.-.', 'D': '-..',  'E': '.',    'F': '..-.', 'G': '--.',  'H': '....', 'I': '..',   'J': '.---', 'K': '-.-',  'L': '.-..',
                 'M': '--',  'N': '-.',  'O': '---',  'P': '.--.', 'Q': '--.-', 'R': '.-.',  'S': '...',  'T': '-',    'U': '..-',  'V': '...-', 'W': '.--',  'X': '-..-',
                 'Y': '-.--','Z': '--..','0': '-----','1': '.----','2': '..---','3': '...--','4': '....-','5': '.....','6': '-....','7': '--...','8': '---..','9': '----.',
                 '=': '-...-'}

inverseMorseAlphabet = dict((v, k) for (k, v) in morseAlphabet.items())

exceptions = ["Wobbuffet", "Arctovish", "Bouffalant", "Froakie", "Arctozolt"]


def decodeMorse(code):
    output_morse = ""
    for letter in code.strip('\n').split(" "):
        if "/" in letter:
            output_morse += " "
            letter = letter.split("/")[1]

        if letter in inverseMorseAlphabet:
            output_morse += inverseMorseAlphabet[letter]
    return output_morse


def cipher_decrypt(ciphertext, key):
    print(ciphertext)
    decrypted = ""

    for c in ciphertext:

        if c.isupper():
            c_index = ord(c) - ord('A')
            # shift the current character to left by key positions to get its original position
            c_og_pos = (c_index - key) % 26 + ord('A')
            c_og = chr(c_og_pos)
            decrypted += c_og


        elif c.islower():
            c_index = ord(c) - ord('a')
            c_og_pos = (c_index - key) % 26 + ord('a')
            c_og = chr(c_og_pos)
            decrypted += c_og

        elif c.isdigit():
            # if it's a number,shift its actual value
            c_og = (int(c) - key) % 10
            decrypted += str(c_og)

        else:
            # if its neither alphabetical nor a number, just leave it like that
            decrypted += c

    return decrypted


def fromDecimal(stringNumbers):
    output_str = ""
    numbers_list = stringNumbers.split(" ")
    print(stringNumbers)

    for number in numbers_list:
        print(number)
        output_str += chr(int(number))

    return output_str


def fromBase64(base64str):
    base64_message = base64str
    base64_bytes = base64_message.encode('ascii')
    message_bytes = base64.b64decode(base64_bytes)
    message = message_bytes.decode('ascii')
    return message


def get_chall(p):
    """
    function by: @CTFKris
    https://ctf.rip/write-ups/crypto/csaw-gottadecrypt/
    """
    z = p.recvuntil((b'What does this mean?', b'flag{'))
    if b'flag{' in z:
        rest = p.recvline()
        log.info(z.decode() + rest.decode())
        quit()
    p.recvline()
    chal = p.recvuntil(b'>> ')
    return chal[:-3].decode().strip()


if __name__ == '__main__':

    # online version:
    #
    #conn = remote('crypto.chal.csaw.io',5001)
    #for i in range(6):
    #    received = get_chall(conn)

    # offline version:
    #
    received = open('input').read()
    word = received.split("What does this mean?\n")[1].strip('\n').strip().strip("\n>>")

    #churro = (fromBase64(fromDecimal(decodeMorse(word))))
    for w in decodeMorse(word).split(" "): print(w)

    n = churro.split("\n")[0].split("=")[1].strip()
    c = churro.split("\n")[2].split("=")[1].strip()

    result = os.system("python3 RsaCtfTool.py --verbosity DEBUG --attack cube_root -n {n} -e 3 --uncipher {c} --output result.txt".format(n=n, c=c))
    with open('result.txt') as result_file:
        result_str = result_file.read()
        result_cesar = cipher_decrypt(result_str, 13)
    os.system("rm result.txt".format(n=n, c=c))

    # online version:
    #
    conn.send(result_cesar + '\n')