django_bcrypt_legacy.py

from django.contrib.auth.hashers import BCryptPasswordHasher
from django.utils.crypto import constant_time_compare
from django.utils.encoding import force_bytes


class DjangoBCryptPasswordHasher(BCryptPasswordHasher):
    """
    Handles legacy passwords wich were hashed with the 'bc$' algorithm via
    django-bcrypt.
    """
    algorithm = "bc"

    def verify(self, password, encoded):
        data = encoded[3:]
        bcrypt = self._load_library()
        return constant_time_compare(data, bcrypt.hashpw(force_bytes(password), data))