include::../description.adoc[]

== Noncompliant Code Example

For https://github.com/Legrandin/pycryptodome[PyCryptodome] module:

----
from Crypto.Cipher import AES
from Crypto.Random import get_random_bytes
from Crypto.Util.Padding import pad, unpad

static_vector = b'x' * AES.block_size
cipher = AES.new(key, AES.MODE_CBC, static_vector)
cipher.encrypt(pad(data, AES.block_size))  # Noncompliant
----

For https://github.com/pyca/cryptography[cryptography] module:

----
from os import urandom
from cryptography.hazmat.primitives.ciphers import Cipher, algorithms, modes

static_vector = b'x' * 16
cipher = Cipher(algorithms.AES(key), modes.CBC(static_vector))
cipher.encryptor()  # Noncompliant
----

== Compliant Solution

For https://github.com/Legrandin/pycryptodome[PyCryptodome] module:

----
from Crypto.Cipher import AES
from Crypto.Random import get_random_bytes
from Crypto.Util.Padding import pad, unpad

random_vector = get_random_bytes(AES.block_size)
cipher = AES.new(key, AES.MODE_CBC, random_vector)
cipher.encrypt(pad(data, AES.block_size))
----

For https://github.com/pyca/cryptography[cryptography] module:

----
from os import urandom
from cryptography.hazmat.primitives.ciphers import Cipher, algorithms, modes

random_vector = urandom(16)
cipher = Cipher(algorithms.AES(key), modes.CBC(random_vector))
cipher.encryptor()
----

include::../see.adoc[]
