Single Sign on Between Drupal and TWiki ,what is the possible solutions ?

Hello all,

I would like to integrate drupal with some existing applications we are using, like TWiki. The big problem is that all of these have their own authentication scheme and code.I So basically I have Drupal and Twiki applications requiring the user to log in at all of them! Are there any SSO solutions in drupal that works with non-drupal code (i.e. include files, code snippets one can use), so that it is possible to log in and authenticate at one place only?

Thanks for your help!