Hi Ankit,
The flow is actually reverse of what you described. When you setup Discourse Connect on your site:
- Clicking the login button will take you to
discourse_connect_urlwith 2 get paramsssoandsig. - The user will enter their credentials on the
discourse_connect_urland will be authenticated by your site, if the auth is successful, then you need to decode the sso and follow the further steps as described in Discourse Connect topic.