Spring CAS authentication with 03 parameters

Question

Dear Spring/CAS experts,

I have to implement a SSO service. Few third party systems going to connect with this SSO, but all these each and every system has different usernames and passwords and also a single user can have many accounts. The requirement is users can register in my SSO and that username and password can use to login via SSO. when entering to a third party system if user has more than one user account in third party system all usernames related to this user should show in a seperate web page. User can click on one and then SSO should inject that selected username to CAS token(or any possible mechanism to map the token with new username) and redirect to third party system. That third party system will validate the token+username.

1. How can I achieve Redirection to separate web page on first authentication with all existing usernames.
2. How can I achieve injecting selected username to existing CAS token and validate username and CAS token by third party app by requesting to CAS server.

Currently I'm using XML configurations. Do I have to do any change in CAS server? Can anybody please explain the mechanism which I can use.

Thanks

Answer 1

Finally I had to clone the CAS and implement the feature according to our requirement. If anyone interesting visit https://github.com/dushanlk/cas/tree/experiment-on-v4.2.6 here. This is not a production ready implementation, just a sketch.