def _g_equal_p_minus_one() -> bool:
g = _p - 1
a = DHClient(_p, g)
b = DHClient(a.p, a.g)
a.gen_session_key(b.public_key)
b.gen_session_key(a.public_key)
a_encrypted_msg = a.encrypt_msg(_msg)
b_encrypted_msg = b.encrypt_msg(_msg)
a_decrypted_msg = a.decrypt_msg(*b_encrypted_msg)
b_decrypted_msg = b.decrypt_msg(*a_encrypted_msg)
if a.public_key == g and b.public_key == g:
key = g
else:
key = 1
key = sha1(key.to_bytes(floor(key.bit_length() / 8) + 1, "big"))[:16]
iv = a_encrypted_msg[0]
cbc = AESCipher(AESCipher.MODE_CBC, key, iv=iv)
mitm_decrypted = pkcs7_unpad(cbc.decrypt(a_encrypted_msg[1]))
return mitm_decrypted == a_decrypted_msg == b_decrypted_msg == _msg
def challenge20(path: str) -> bool:
with open(path) as f:
lines = f.readlines()
plain_texts = [base64.b64decode(s) for s in lines]
secrets = []
for i in range(len(plain_texts)):
ctr = AESCipher(AESCipher.MODE_CTR, _KEY, nonce=_NONCE)
secrets.append(ctr.encrypt(plain_texts[i]))
max_len = max(len(s) for s in secrets)
keystream = bytearray()
for i in range(max_len):
i = len(keystream)
char_chain = bytes([s[i] for s in secrets if len(s) > i])
possible_keys = rank_xor_single_byte_key(char_chain)
key_byte = possible_keys[_FIX_MAP.get(i, 0)]
keystream += key_byte
pt = [xor_byte_arrays(s, keystream) for s in secrets]
if pt == plain_texts:
return True
return False
def decrypt_msg(self, iv: bytes, msg: bytes) -> bytes:
key = sha1(
self._session_key.to_bytes(
floor(self._session_key.bit_length() / 8) + 1, "big"))[:16]
cbc = AESCipher(AESCipher.MODE_CBC, key, iv=iv)
return pkcs7_unpad(cbc.decrypt(msg))
def _edit(cipher_text: bytes, offset: int, new_text: bytes) -> bytes:
ctr = AESCipher(AESCipher.MODE_CTR, _KEY, nonce=_NONCE)
plain_text = ctr.decrypt(cipher_text)
plain_text = plain_text[:offset] + new_text + plain_text[offset +
len(new_text):]
return ctr.encrypt(plain_text)
def _oracle(iv: bytes, ct: bytes) -> bool:
cbc = AESCipher(AESCipher.MODE_CBC, _KEY, iv=iv)
try:
pkcs7_unpad(cbc.decrypt(ct))
except PKCS7Error:
return False
return True
def encrypt_msg(self, msg: bytes) -> Tuple[bytes, bytes]:
key = sha1(
self._session_key.to_bytes(
floor(self._session_key.bit_length() / 8) + 1, "big"))[:16]
iv = gen_random_bytes(16)
cbc = AESCipher(AESCipher.MODE_CBC, key, iv=iv)
return (iv, cbc.encrypt(pkcs7_pad(msg)))
def challenge07(path: str) -> bytes:
key = b"YELLOW SUBMARINE"
cipher = AESCipher(AESCipher.MODE_ECB, key)
with open(path) as f:
lines = f.readlines()
cipher_text = base64.b64decode("".join(lines))
msg = cipher.decrypt(cipher_text).split(b"\n")
return msg[0]
def challenge10(path: str) -> bytes:
key = b"YELLOW SUBMARINE"
iv = b"\x00" * 16
cipher = AESCipher(AESCipher.MODE_CBC, key, iv=iv)
with open(path) as f:
lines = f.readlines()
cipher_text = base64.b64decode("".join(lines))
plain_text = cipher.decrypt(cipher_text).split(b"\n")
return plain_text[0]
def challenge18() -> bool:
ct = base64.b64decode(
"L77na/nrFsKvynd6HzOoG7GHTLXsTVu9qvY/2syLXzhPweyyMTJULu/6/kXX0KSvoOLSFQ=="
)
result = b"Yo, VIP Let's kick it Ice, Ice, baby Ice, Ice, baby "
key = b"YELLOW SUBMARINE"
nonce = b"\x00" * 8
ctr = AESCipher(AESCipher.MODE_CTR, key, nonce=nonce, counter=0)
res = ctr.decrypt(ct)
return res == result
def test_aes_ecb_decrypt(self):
# Test vectors from NIST Special Publication 800-38A 2001 Edition
key = bytes.fromhex("2b7e151628aed2a6abf7158809cf4f3c")
ct = bytes.fromhex("3ad77bb40d7a3660a89ecaf32466ef97"
"f5d3d58503b9699de785895a96fdbaaf"
"43b1cd7f598ece23881b00e3ed030688"
"7b0c785e27e8ad3f8223207104725dd4")
pt = bytes.fromhex("6bc1bee22e409f96e93d7e117393172a"
"ae2d8a571e03ac9c9eb76fac45af8e51"
"30c81c46a35ce411e5fbc1191a0a52ef"
"f69f2445df4f9b17ad2b417be66c3710")
ecb = AESCipher(AESCipher.MODE_ECB, key)
result = ecb.decrypt(ct)
assert result == pt, "The result does not match the expected value"
def test_aes_cbc_encrypt(self):
# Test vectors from NIST Special Publication 800-38A 2001 Edition
key = bytes.fromhex("2b7e151628aed2a6abf7158809cf4f3c")
iv = bytes.fromhex("000102030405060708090a0b0c0d0e0f")
pt = bytes.fromhex("6bc1bee22e409f96e93d7e117393172a"
"ae2d8a571e03ac9c9eb76fac45af8e51"
"30c81c46a35ce411e5fbc1191a0a52ef"
"f69f2445df4f9b17ad2b417be66c3710")
ct = bytes.fromhex("7649abac8119b246cee98e9b12e9197d"
"5086cb9b507219ee95db113a917678b2"
"73bed6b8e3c1743b7116e69e22229516"
"3ff1caa1681fac09120eca307586e1a7")
cbc = AESCipher(AESCipher.MODE_CBC, key, iv=iv)
result = cbc.encrypt(pt)
assert result == ct, "The result does not match the expected value"
def challenge19() -> bool:
secrets = []
for i in range(len(_STRINGS)):
ctr = AESCipher(AESCipher.MODE_CTR, _KEY, nonce=_NONCE)
secrets.append(ctr.encrypt(_STRINGS[i]))
max_len = max(len(s) for s in secrets)
keystream = bytearray()
for i in range(max_len):
char_chain = bytes([s[i] for s in secrets if len(s) > i])
possible_keys = rank_xor_single_byte_key(char_chain)
key_byte = possible_keys[_FIX_MAP.get(i, 0)]
keystream += key_byte
pt = [xor_byte_arrays(s, keystream) for s in secrets]
if pt == _STRINGS:
return True
return False
def challenge34() -> bool:
p = int.from_bytes(
bytes.fromhex("ffffffffffffffffc90fdaa22168c234c4c6628b80dc1cd129024"
"e088a67cc74020bbea63b139b22514a08798e3404ddef9519b3cd"
"3a431b302b0a6df25f14374fe1356d6d51c245e485b576625e7ec"
"6f44c42e9a637ed6b0bff5cb6f406b7edee386bfb5a899fa5ae9f"
"24117c4b1fe649286651ece45b3dc2007cb8a163bf0598da48361"
"c55d39a69163fa8fd24cf5f83655d23dca3ad961c62f356208552"
"bb9ed529077096966d670c354e4abc9804f1746c08ca237327fff"
"fffffffffffff"),
"big",
)
g = 2
msg = b"test"
a = DHClient(p, g)
b = DHClient(a.p, a.g)
a.gen_session_key(b.p)
b.gen_session_key(a.p)
a_encrypted_msg = a.encrypt_msg(msg)
b_encrypted_msg = b.encrypt_msg(msg)
a_decrypted_msg = a.decrypt_msg(*b_encrypted_msg)
b_decrypted_msg = b.decrypt_msg(*a_encrypted_msg)
key = 0
key = sha1(key.to_bytes(floor(key.bit_length() / 8) + 1, "big"))[:16]
iv = a_encrypted_msg[0]
cbc = AESCipher(AESCipher.MODE_CBC, key, iv=iv)
mitm_decrypted = pkcs7_unpad(cbc.decrypt(a_encrypted_msg[1]))
return mitm_decrypted == a_decrypted_msg == b_decrypted_msg == msg
def test_aes_ctr_decrypt(self):
key = bytes.fromhex("2b7e151628aed2a6abf7158809cf4f3c")
nonce = bytes.fromhex("f0f1f2f3f4f5f6f7")
counter = 0xF8F9FAFBFCFDFEFF
ct = bytes.fromhex("874d6191b620e3261bef6864990db6ce"
"9806f66b7970fdff8617187bb9fffdff"
"5ae4df3edbd5d35e5b4f09020db03eab"
"1e031dda2fbe03d1792170a0f3009cee")
pt = bytes.fromhex("6bc1bee22e409f96e93d7e117393172a"
"ae2d8a571e03ac9c9eb76fac45af8e51"
"30c81c46a35ce411e5fbc1191a0a52ef"
"f69f2445df4f9b17ad2b417be66c3710")
cbc = AESCipher(
AESCipher.MODE_CTR,
key,
nonce=nonce,
counter=counter,
counter_byteorder="big",
)
result = cbc.decrypt(ct)
assert result == pt, "The result does not match the expected value"
def _encrypt_it(path: str) -> (bytes, bytes):
ecb = AESCipher(AESCipher.MODE_ECB, key=b"YELLOW SUBMARINE")
with open(path) as f:
cipher_text = base64.b64decode(f.read())
plain_text = ecb.decrypt(cipher_text)
ctr = AESCipher(AESCipher.MODE_CTR, _KEY, nonce=_NONCE)
cipher_text = ctr.encrypt(plain_text)
return cipher_text, plain_text
def _encryption_oracle(bytes_: bytes) -> Tuple[bytes, str]:
key = gen_random_bytes(16)
iv = gen_random_bytes(16)
prefix = gen_random_bytes(random.randint(5, 10))
suffix = gen_random_bytes(random.randint(5, 10))
pt = prefix + bytes_ + suffix
cbc_mode = random.choice([True, False])
if cbc_mode:
cbc = AESCipher(AESCipher.MODE_CBC, key, iv=iv)
ct = cbc.encrypt(pkcs7_pad(pt))
answer = "cbc"
else:
ecb = AESCipher(AESCipher.MODE_ECB, key)
ct = ecb.encrypt(pkcs7_pad(pt))
answer = "ecb"
return ct, answer
#!/usr/bin/env python3
from urllib.parse import quote, unquote
from functions.xor import xor_byte_arrays
from functions.aes import AESCipher, gen_random_bytes, pkcs7_unpad, pkcs7_pad
_ctr = AESCipher(AESCipher.MODE_CTR,
gen_random_bytes(16),
nonce=gen_random_bytes(8))
def _parse_cookie(string: str) -> dict:
return {
k: unquote(v)
for k, v in [s.split("=", 1) for s in string.split(";")]
}
def _get_token(user_data: str) -> bytes:
prefix = "comment1=cooking%20MCs;userdata="
suffix = ";comment2=%20like%20a%20pound%20of%20bacon"
token = prefix + quote(user_data) + suffix
return _ctr.encrypt(pkcs7_pad(token.encode("latin")))
def _is_admin(token: bytes) -> bool:
decrypted_token = pkcs7_unpad(_ctr.decrypt(token))
cookie = _parse_cookie(decrypted_token.decode("latin"))
from functions.aes import gen_random_bytes, AESCipher, pkcs7_pad
RESULT = b"""Rollin' in my 5.0
With my rag-top down so my hair can blow
The girlies on standby waving just to say hi
Did you stop? No, I just drove by
"""
_SECRET = base64.b64decode(
"Um9sbGluJyBpbiBteSA1LjAKV2l0aCBteSByYWctdG9wIGRvd24gc28gbXkg"
"aGFpciBjYW4gYmxvdwpUaGUgZ2lybGllcyBvbiBzdGFuZGJ5IHdhdmluZyBq"
"dXN0IHRvIHNheSBoaQpEaWQgeW91IHN0b3A/IE5vLCBJIGp1c3QgZHJvdmUg"
"YnkK")
_ecb = AESCipher(AESCipher.MODE_ECB, gen_random_bytes(16))
def _encrypt_it(bytes_: bytes) -> bytes:
pt = bytes_ + _SECRET
ct = _ecb.encrypt(pkcs7_pad(pt))
return ct
def _get_info() -> Tuple[int, int]:
length_without_padding = len(_encrypt_it(bytes()))
length_with_padding = length_without_padding
padding = bytes()
#!/usr/bin/env python3
from urllib.parse import quote, unquote
from functions.xor import xor_byte_arrays
from functions.aes import AESCipher, gen_random_bytes, pkcs7_unpad, pkcs7_pad
_cbc = AESCipher(AESCipher.MODE_CBC,
gen_random_bytes(16),
iv=gen_random_bytes(16))
def _parse_cookie(string: str) -> dict:
return {
k: unquote(v)
for k, v in [s.split("=", 1) for s in string.split(";")]
}
def _get_token(user_data: str) -> bytes:
prefix = "comment1=cooking%20MCs;userdata="
suffix = ";comment2=%20like%20a%20pound%20of%20bacon"
token = prefix + quote(user_data) + suffix
return _cbc.encrypt(pkcs7_pad(token.encode("latin")))
def _is_admin(token: bytes) -> bool:
decrypted_token = pkcs7_unpad(_cbc.decrypt(token))
cookie = _parse_cookie(decrypted_token.decode("latin"))
def _encrypt(pt: bytes) -> (bytes, bytes):
iv = gen_random_bytes(16)
cbc = AESCipher(AESCipher.MODE_CBC, _KEY, iv=iv)
ct = cbc.encrypt(pkcs7_pad(pt))
return iv, ct
#!/usr/bin/env python3
from typing import Union
from urllib.parse import quote, unquote
from functions.aes import AESCipher, gen_random_bytes, pkcs7_unpad, pkcs7_pad
from functions.xor import xor_byte_arrays
_KEY = gen_random_bytes(16)
_cbc = AESCipher(AESCipher.MODE_CBC, _KEY, iv=_KEY)
def _parse_cookie(string: str) -> dict:
return {
k: unquote(v)
for k, v in [s.split("=", 1) for s in string.split(";")]
}
def _get_token(user_data: str) -> bytes:
prefix = "comment1=cooking%20MCs;userdata="
suffix = ";comment2=%20like%20a%20pound%20of%20bacon"
token = prefix + quote(user_data) + suffix
return _cbc.encrypt(pkcs7_pad(token.encode("latin")))
def _is_admin(token: bytes) -> Union[bool, Exception]:
# decrypted_token = pkcs7_unpad(_cbc.decrypt(token))
decrypted_token = _cbc.decrypt(token)