def encryption_oracle(plaintext: bytes) -> bytes:
encoded_to_append = "Um9sbGluJyBpbiBteSA1LjAKV2l0aCBteSByYWctdG9wIGRvd24gc28gbXkgaGFpciBjYW4gYmxvdwpUaGUgZ2lybGllcyBvbiBzdGFuZGJ5IHdhdmluZyBqdXN0IHRvIHNheSBoaQpEaWQgeW91IHN0b3A/IE5vLCBJIGp1c3QgZHJvdmUgYnkK" # noqa
to_append = base64.b64decode(encoded_to_append)
garbage_padded_text = b"".join([prepend, plaintext, to_append])
padded_text = pkcs7_pad(garbage_padded_text)
ciphertext = encrypt_aes_ecb(padded_text, consistent_key)
return ciphertext
def encryption_oracle(plaintext: bytes) -> Tuple[str, bytes]:
key = generate_16_random_bytes()
prepadding = bytes(
[random.randrange(0, 0xff) for i in range(0, random.randrange(5, 11))])
postpadding = bytes(
[random.randrange(0, 0xff) for i in range(0, random.randrange(5, 11))])
garbage_padded_text = b"".join([prepadding, plaintext, postpadding])
padded_text = pkcs7_pad(garbage_padded_text)
if random.random() > 0.5:
# ECB
mode = "ECB"
ciphertext = encrypt_aes_ecb(padded_text, key)
else:
# CBC
mode = "CBC"
iv = generate_16_random_bytes()
ciphertext = encrypt_aes_cbc(padded_text, key, iv)
return mode, ciphertext
def encrypt_aes_cbc(plaintext: bytes, key: bytes, iv: bytes) -> bytes:
if len(plaintext) % 16 == 0:
num_chunks = len(plaintext) // 16
else:
num_chunks = len(plaintext) // 16 + 1
encrypted = []
prev_cipher_chunk = None
for i in range(0, num_chunks):
curr_chunk = plaintext[i * 16:(i + 1) * 16]
if len(curr_chunk) < 16:
curr_chunk = pkcs7_pad(curr_chunk)
if not prev_cipher_chunk:
xored_chunk = xor_bytes(curr_chunk, iv)
else:
xored_chunk = xor_bytes(curr_chunk, prev_cipher_chunk)
encrypted_chunk = encrypt_aes_ecb(xored_chunk, key)
encrypted.append(encrypted_chunk)
prev_cipher_chunk = encrypted_chunk
return b"".join(encrypted)
def profile_oracle(email: bytes) -> bytes:
return encrypt_aes_ecb(pkcs7_pad(create_querystring(profile_for(email))), consistent_key)
def cbc_oracle(plaintext: bytes) -> bytes:
sanitized_plaintext = plaintext.replace(b";",
b"\";\"").replace(b"=", b"\"=\"")
total = b"".join([prepend, sanitized_plaintext, append])
padded_total = pkcs7_pad(total)
return encrypt_aes_cbc(padded_total, consistent_key, consistent_iv)