Khan Academy uses a variant of OAuth1 authentication flow. Check the API details at Khan Academy API Authentication.
Follow this steps in order to use the backend:
Register a new application at Khan Academy API Apps,
Fill Consumer Key and Consumer Secret values:
SOCIAL_AUTH_KHANACADEMY_OAUTH1_KEY = '' SOCIAL_AUTH_KHANACADEMY_OAUTH1_SECRET = ''
Add the backend to
AUTHENTICATION_BACKENDS = ( ... 'social_core.backends.khanacademy.KhanAcademyOAuth1', ... )