'Retrieve and decrypt auth_state for the user'

@gen.coroutine
def get_auth_state(self):

    encrypted = self.encrypted_auth_state
    if (encrypted is None):
        return None
    try:
        auth_state = (yield decrypt(encrypted))
    except (ValueError, InvalidToken, EncryptionUnavailable) as e:
        self.log.warning('Failed    to    retrieve    encrypted    auth_state    for    %s    because    %s', self.name, e)
        return
    if auth_state:
        if (len(CryptKeeper.instance().keys) > 1):
            (yield self.save_auth_state(auth_state))
    return auth_state
