HTTPClient - Set a proxy with a Digest Auth

Did anyone ever manage to make an http call through a proxy server using a digest access authentication?

I tried with basic authentication, but if I set the proxy and the username+password from the network settings, my http request will crash the whole app. Same thing if I set only the proxy server and send the auth through

http.setRequestHeader('Authorization', 'Basic ' + Ti.Utils.base64encode(username+':'+password));