Created
October 13, 2021 17:10
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import itertools | |
import json | |
import math | |
import string | |
############################ | |
encrypted_hex = """ | |
put the encrypted response here | |
""" | |
key_len = 16 | |
key_charset = string.ascii_lowercase[:14] | |
decrypted_charset = string.printable | |
########################### | |
key_charset_bytes = [ord(c) for c in key_charset] | |
decrypted_charset_bytes = [ord(c) for c in decrypted_charset] | |
def decrypt(key_bytes, encrypted_bytes): | |
key_len = len(key_bytes) | |
decrypted = [] | |
for (i, b) in enumerate(encrypted_bytes): | |
decrypted.append(b ^ key_bytes[i % key_len]) | |
return bytes(decrypted) | |
def find_candidates_key_bytes(encrypted_bytes, key_offset): | |
bytes_to_check = encrypted_bytes[key_offset::key_len] | |
for k in key_charset_bytes: | |
if all(k ^ b in decrypted_charset_bytes for b in bytes_to_check): | |
yield k | |
def is_valid_json(decrypted): | |
try: | |
json.loads(decrypted) | |
except json.JSONDecodeError: | |
return False | |
return True | |
def find_key(encrypted_bytes): | |
candidates_key_bytes = [ | |
list(find_candidates_key_bytes(encrypted_bytes, i)) for i in range(16) | |
] | |
number_of_keys = math.prod(len(l) for l in candidates_key_bytes) | |
print(f"{number_of_keys} keys to test") | |
for key in itertools.product(*candidates_key_bytes): | |
decrypted = decrypt(key, encrypted_bytes) | |
if is_valid_json(decrypted): | |
key_ascii = "".join(chr(c) for c in key) | |
print(f"potential key found: {key_ascii}") | |
if __name__ == "__main__": | |
find_key(bytes.fromhex(encrypted_hex)) |
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