Today, we are happy to announce the launch of AuthSub for ActionScript, a new component of the well-known AuthSub authentication interface for the Google Data Protocol. This new feature enables Flash and Silverlight applications to access data securely on behalf of a user, without the application ever seeing the user’s private login credentials.

To use AuthSub for Actionscript (or as we’re calling it, AuthSubAS), first ensure that the API you are accessing offers cross-domain support. To do this, simply check for a crossdomain.xml file like those offered by the Picasa Web Albums Data API and the YouTube Data API. Then, if the API supports cross-domain scripting, you can simply point your Flash app to https://accounts.googleapis.com/accounts/AuthSub{Request,SessionToken} and authenticate. If you’re familiar with how AuthSub for JavaScript works, AuthSubAS works in much the same way. For more information, see the AuthSub for ActionScript guide and check out this code sample.

Currently, cross-domain requests are only supported by the Picasa Web Albums Data API and the YouTube Data API.  However, as more APIs offer cross-domain scripting through an open crossdomain.xml file, the AuthSubAS authentication will work automatically. For questions about a specific API or to encourage your API to provide AuthSubAS support sooner, visit your API’s support group in Google Groups.