Fernet Symmetrical Encryption Implementation

fernet_symmetry.py

import base64
from cryptography.hazmat.backends import default_backend
from cryptography.hazmat.primitives import hashes
from cryptography.hazmat.primitives.kdf.pbkdf2 import PBKDF2HMAC
from cryptography.fernet import Fernet

def encrypt_text(text, salt):
    def generate_key(master, salt):
        kdf = PBKDF2HMAC(
            algorithm=hashes.SHA512(),
            length=32,
            salt=salt.encode(),
            iterations=100,
            backend=default_backend()
        )
        key = base64.urlsafe_b64encode(kdf.derive(master.encode()))
        return key

    key = generate_key(text, salt)
    encryptor = Fernet(key)
    hash = encryptor.encrypt(text.encode())
    return hash.decode(), str(key)[2:-1]


def decrypt_text(hash, key):
    decryptor = Fernet(key)
    text = decryptor.decrypt(hash.encode())
    return text.decode()

Thank you!
It would be even nicer if you showed how to save the key as a string for saving and sending and then re-constitute that string to the key on the decrypt side.

def decrypt_text(hash, key_text):
    key = bytes(saved_text, 'utf-8')
    decryptor = Fernet(key)
    text = decryptor.decrypt(hash.encode())
    return text.decode()

# usage:

saved_text = "I41_sE8EtPvzb8-XooyiuG4KF_-AuGBDYQNvryTP0BY="
decrypted = decrypt_text(hash, saved_text)
print("decrypted: ", decrypted)