The changes to add auth are in the link below. Manually tested only. Returns the string "Unauthorized" if the user is unauthorized (no username or wrong password), otherwise returns the desired json. Credit must go to the author of txjsonrpc for including a nice wrapper for auth.

https://github.com/thedawnrider/BitcoinArmory-Daemon/commit/32cfd4697fed5546c57f5815b15a37f79988db74

inspired entirely by

https://github.com/bbqsrc/txjsonrpc/blob/master/examples/webAuth/server.tac

and if you want to do password storage differently than a text file (which I know you don't)

https://twistedmatrix.com/documents/8.1.0/api/twisted.cred.checkers.ICredentialsChecker.html

Hope this helps.