[FIXED] Django Model Field for a Secure String

Issue

In short: I want to store strings encrypted in the database and decrypt them when i need them. What is the best practice for this?

Context: I am building an application that uses a 3rd party API that requires a login and password. I want to store the credentials that will be used for the 3rd party API in the database as their will be many different credentials. I was looking on the django documentation and on stackoverflow but i only find things that hash passwords.

EDIT: I did some more searching and i realy liked this: https://github.com/georgemarshall/django-cryptography

Anyone some other ideas or opinions on the repository i found?

Solution

You should create a custom model field and override the from_db_value() and get_prep_value to encrypted and decrypt the string. You can use many packages to do the encryption algorithm.

With cryptography you can do something like:

from django.db.models import CharField
from cryptography.fernet import Fernet
from django.conf import settings
from cryptography.hazmat.backends import default_backend
from cryptography.hazmat.primitives import hashes
from cryptography.hazmat.primitives.kdf.pbkdf2 import PBKDF2HMAC

class SecureString(CharField):
    """Custom Encrypted Field"""

    kdf = PBKDF2HMAC(algorithm=hashes.SHA256(), 
                     length=32, 
                     salt=salt, 
                     iterations=100000, 
                     backend=default_backend())

    key = base64.urlsafe_b64encode(kdf.derive(settings.SECRET_KEY))

    f = Fernet(key)

    def from_db_value(self, value, expression, connection):
        return f.decrypt(value)

    def get_prep_value(self, value):
        return f.encrypt(value)

Note: You should abstract the encryption logic for a more optimal solution.

Answered By - Carlos Saldana