Java :: Flash - Rewriting Inbound Server Authorization Headers Prior To Authentication?

Authentication is performed with Basic auth over SSL (although the password inside the basic auth is SHA-2'ed). The issue is that using basic authentication for the Flash client is causing the standard browser log-in box to appear because of "WWW-Authentication: Basic" in the header. Flash is unable to bypass this by manually setting the Authorization header prior to the request.Other clients need to be able to authenticate via the existing mechanisms, so rewriting the authentication logic would not be ideal.

I have the idea that the authorization headers sent to and received from flash client could be dynamically rewritten to use another name for Basic auth which would cause the browser not to understand the auth mechanism and not present the dialog box. Authentication headers to and from Tomcat could be rewritten from "WWW-Authenticate: Basic" to "WWW-Authenticate: PretendBasic" but ideally the built in container security could still handle the basic auth after the rewrite.

I wrote a filter to rewrite inbound headers as "WWW-Authenticate: PretendBasic" as "WWW-Authenticate: Basic" hoping the next filter chain would be auth and the request would be handled as normal. Unfortunately the Servlet specification states that a filter cannot be inserted prior to authentication. I think the only possibility of this working is to create a stackable JAAS authentication module that would first perform a header rewrite on requests if coming from the Flash client, and then pass authentication through to the existing container managed security systems.