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2AES meet in the middle attack
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#!/usr/bin/env python | |
import base64 | |
from Cryptodome.Cipher import AES | |
import hashlib | |
from Cryptodome.Random import get_random_bytes | |
import string | |
from tqdm import tqdm | |
import base64 | |
test = b'Double AES encryption for twice the strength.Win' | |
encrypted_test = '0mu0T97looX5/Oorw8ASGxfqMqrNoFajZupXrjtIAj7ECJdQXZzEmbEwdRV2J2MI' | |
flag = 'lIZMVkA+pbiOxh3nNdV2bWz3gXovIy4fG7yCHa5FT44=' | |
encrypted_test = base64.b64decode(encrypted_test) | |
flag = base64.b64decode(flag) | |
iv = hashlib.md5(b"infernoCTF").digest() | |
alphabet = string.printable | |
key_base = '0'*29 | |
# decrypting | |
phase1 = {} | |
data = encrypted_test | |
for a in tqdm(string.printable): | |
for b in string.printable: | |
for c in string.printable: | |
key = key_base+a+b+c | |
key = key.encode() | |
cipher_decrypt = AES.new(key, AES.MODE_CBC, iv=iv) | |
ciphertext = cipher_decrypt.decrypt(data) | |
phase1[key] = ciphertext | |
print('P1 done') | |
# encrypting | |
phase2 = {} | |
data = test | |
for a in tqdm(string.printable): | |
for b in string.printable: | |
for c in string.printable: | |
key = key_base+a+b+c | |
key = key.encode() | |
cipher_encrypt = AES.new(key, AES.MODE_CBC, iv=iv) | |
ciphertext = cipher_encrypt.encrypt(data) | |
phase2[key] = ciphertext | |
print('P2 done') | |
s1 = set(phase1.values()) | |
s2 = set(phase2.values()) | |
s3 = s1 & s2 | |
match = s3.pop() | |
for k,v in phase1.items(): | |
if v == match: | |
key1 = k | |
print(f'Key1: {key1}') | |
for k,v in phase2.items(): | |
if v == match: | |
key2 = k | |
print(f'Key2: {key2}') | |
# decrypt flag | |
data = flag | |
cipher_decrypt = AES.new(key1, AES.MODE_CBC, iv=iv) | |
ciphertext = cipher_decrypt.decrypt(data) | |
cipher_decrypt = AES.new(key2, AES.MODE_CBC, iv=iv) | |
ciphertext = cipher_decrypt.decrypt(ciphertext) | |
print(ciphertext.decode('utf-8')) | |
# infernoCTF{M33t_in_Th£_M1ddL3!} |
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