crypto.py

from cryptography.hazmat.primitives.ciphers.aead import AESGCM
from cryptography.hazmat.primitives.kdf.scrypt import Scrypt
import os

def derive_key(master_password: str, salt: bytes) -> bytes:
    kdf = Scrypt(
        salt=salt,
        length=32,
        n=2**14,
        r=8,
        p=1,
    )
    return kdf.derive(master_password.encode())

def encrypt(secret: str, key: bytes) -> bytes:
    aesgcm = AESGCM(key)
    nonce = os.urandom(12)
    ciphertext = aesgcm.encrypt(nonce, secret.encode(), None)
    return nonce + ciphertext

def decrypt(blob: bytes, key: bytes) -> str:
    nonce = blob[:12]
    ciphertext = blob[12:]
    aesgcm = AESGCM(key)
    return aesgcm.decrypt(nonce, ciphertext, None).decode()