(FTR Digits was retired on 30/09/2017) Digits verification

digits.py

class DigitsVerification:
    DIGITS_API_URL = 'https://api.digits.com'
    AUTH_PROVIDER_KEY = 'apiUrl'
    CREDENTIALS_KEY = 'credentials'

    def __call__(self, credentials):
        auth_provider = self.validate_auth_provider(credentials)
        if auth_provider is None:
            return None

        credentials = self.validate_credentials(credentials)
        if credentials is None:
            return None

        headers = self.make_headers(credentials)

        response = requests.get(auth_provider, headers=headers)

        if response.status_code == 200:
            return True

    @staticmethod
    def make_headers(credentials):
        return {'Authorization': credentials}

    @staticmethod
    def validate_auth_provider(credentials):
        auth_provider = credentials.get(DigitsVerification.AUTH_PROVIDER_KEY, '')
        if auth_provider.startswith(DigitsVerification.DIGITS_API_URL):
            return auth_provider

    @staticmethod
    def validate_credentials(credentials):
        credentials = credentials.get(DigitsVerification.CREDENTIALS_KEY, '')

        key = 'oauth_consumer_key="'
        start = credentials.index(key) + len(key)
        end = start + len(settings.DIGITS_CONSUMER_KEY)
        if credentials[start:end] != settings.DIGITS_CONSUMER_KEY:
            return None
        return credentials