def encrypt_profile(email: str) -> bytes:
global key
if key is None:
key = generate_bytes()
data = profile_for(email)
data = pkcs7_pad(bytes(data, "ascii"))
return encrypt_aes_128_ecb(data, key)
def attack_profile() -> bytes:
email = "*****@*****.**"
admin = pkcs7_pad(b"admin").decode("ascii")
padding = "x" * (16 - len("email="))
enc_bytes = encrypt_profile(email)
enc_admin = encrypt_profile(padding + admin + "@foo.bar")
return enc_bytes[0:32] + enc_admin[16:32]
def test_challenge09(self):
if 9 not in self.tests:
self.skipTest("")
test = b"YELLOW SUBMARINE"
expected = b"YELLOW SUBMARINE\x04\x04\x04\x04"
actual = pkcs7_pad(test, 20)
self.assertEqual(expected, actual)
expected = b"\x10" * 16
actual = pkcs7_pad(b"")
self.assertEqual(expected, actual)
expected = b"1234567890abcdef" + b"\x10" * 16
actual = pkcs7_pad(b"1234567890abcdef")
self.assertEqual(expected, actual)
expected = b"1" + b"\x0f" * 15
actual = pkcs7_pad(b"1")
self.assertEqual(expected, actual)
def encryption_oracle_ecb_cbc(data: bytes, is_ecb: bool) -> bytes:
key = generate_bytes()
before = generate_bytes(randint(5, 10))
after = generate_bytes(randint(5, 10))
data = before + data + after
data = pkcs7_pad(data)
if is_ecb:
output = encrypt_aes_128_ecb(data, key)
else:
iv = generate_bytes()
output = encrypt_cbc(data, key, iv)
return output
def encrypt_cbc(block: bytes,
key: bytes,
vector: bytes = b'\0' * 16,
block_size: int = 16,
self=None) -> bytes:
if not block:
return b""
left = pkcs7_pad(block[:block_size], block_size)
right = block[block_size:]
xored = fixed_xor(left, vector)
left_res = encrypt_aes_128_ecb(xored, key)
right_res = encrypt_cbc(right, key, left_res)
return left_res + right_res
def test_cbc(self):
if "cbc" not in self.tests:
self.skipTest("")
data = b"1234567890"
key = b"YELLOW SUBMARINE"
iv = 16 * b"\0"
cipher = AES.new(key, AES.MODE_CBC, iv)
expected = cipher.encrypt(pkcs7_pad(data, AES.block_size))
actual = encrypt_cbc(data, key, iv)
self.assertEqual(expected, actual)
cipher = AES.new(key, AES.MODE_CBC, iv)
expected = strip_padding(cipher.decrypt(expected))
actual = decrypt_cbc(actual, key, iv)
self.assertEqual(expected, actual)
data = b"1234567890abcdef"
cipher = AES.new(key, AES.MODE_CBC, iv)
expected = cipher.encrypt(data)
actual = encrypt_cbc(data, key, iv)
self.assertEqual(expected, actual)
def encryption_oracle_ecb(data: bytes) -> bytes:
global key
data = pkcs7_pad(data + unknown_string)
return encrypt_aes_128_ecb(data, key)