aes_cryptography.py

from cryptography.hazmat.backends import default_backend
from cryptography.hazmat.primitives import hashes, padding
from cryptography.hazmat.primitives.kdf.pbkdf2 import PBKDF2HMAC
from cryptography.hazmat.primitives.ciphers import Cipher, algorithms, modes
import os

# to get high entropy paswword from a low entropy password
def generate_high_entropy_key(password, salt):
    kdf = PBKDF2HMAC(
        algorithm=hashes.SHA256(),
        iterations=100000,
        salt=salt,
        length=32
    )
    key = kdf.derive(password.encode('utf-8'))
    return key

# the aes encryption
def aes_encrypt(key, plaintext):
    iv = os.urandom(16)
    cipher = Cipher(algorithms.AES(key), modes.CFB(iv), backend=default_backend())
    encryptor = cipher.encryptor()
    ciphertext = encryptor.update(plaintext) + encryptor.finalize()
    return iv + ciphertext

# the aes decryption
def aes_decrypt(key, ciphertext):
    iv = ciphertext[:16]
    ciphertext = ciphertext[16:]
    cipher = Cipher(algorithms.AES(key), modes.CFB(iv), backend=default_backend())
    decryptor = cipher.decryptor()
    plaintext = decryptor.update(ciphertext) + decryptor.finalize()
    return plaintext

# print(generate_high_entropy_key("khritish", b"123wer"))
# print(generate_high_entropy_key("hellojoe", b"123wer"))
# key = generate_high_entropy_key("khritish", b"123wer")
# cipher = aes_encrypt(key, b"Hi this is Khritish")
# print(aes_decrypt(key, cipher))