[otrs] SSO

Hello, We have a central portal that users are logged into. I currently have the portal pulling a list of the users recent OTRS tickets and a link which directs them into OTRS. However, they have to log into OTRS using their username and password. Is there an API function where I can obtain a token of some sort for a specific username and add the token to a URL which will allow me to redirect the user into OTRS while allowing them to bypass the login prompt? Thanks, Kris