Thrust/parry/counter: the history of Web authentication

A beautiful piece of writing by Schabse presents the history of Web authentication as a series of conversational gambits and ripostes between someone who wants to let users prove their identity online, and someone who wants to impersonate those users. It's a great way to present a subject that's both esoteric and vital, and I've never seen it before.

Defender: Users will enter a username & password, and I will give them an authentication cookie for me to trust in the future.

Attacker: I will watch your network traffic and steal the passwords as they come down the wire.

Defender: I will change the

to submit over HTTPS, so you won't see any readable passwords.

Attacker: I will run an active MITM attack as the user loads the login page, and insert Javascript that sends the password to my server in the background.

Defender: I will serve the login page itself over HTTPS too, so you won't be able to read or change it.

Attacker: I will watch your network traffic and steal the resulting authentication cookies, so I can still impersonate users even without knowing the password.

Defender: I will serve the entire site over HTTPS (and mark the cookie as Secure), so you won't be able to see any cookies.

Attacker: I will run an active MITM attack against your entire site and serve it over HTTP, letting me see all of your traffic (including passwords and cookies) again.

Defender: I will serve a Strict-Transport-Security header, telling the browser to always refuse to load my site over HTTP (assuming the user has already visited the site over a trusted connection to establish a trust anchor).

Attacker: I will find or compromise a shady certificate authority and get my own certificate for your domain name, letting me run my MITM attack and still serve HTTPS.

Defender: I will serve a Public-Key-Pins header, telling the browser to refuse to load my site with any certificate other than the one I specify.