HTML request Node - Digest authentication header

Hi guys
I have a Http Request node to send a GET with Digest authentication.
If I check the "Use authentication", select the "Digest" option and write the user and password, work perfectly.

Can any share some example of how set the msg.header for send the authentication data thru the input at the request node?

I tryed something like that and several variants, but it not work:

msg.headers = 
Authorization: "Digest " + "user:pass"