I find this advice really strange. In all the password-related research studies I’ve read, and in all my conversations with computer users, I don’t think I’ve once heard someone complain that they are worried about typos in their password. People will complain at length about forgetting what their password is in the first place, and this is why most choose overly-simple passwords, or just write them down.

It seems like Nielsen has invented a problem where none exists. Nonetheless, he recommends that websites stop masking users’ passwords as they are entered. This whole viewpoint is wrong for a number of reasons:

1. Nielsen claims that password masking is only done today because “it was the default in the Web’s early days”. In fact, it has been the default as long as computers have used passwords as an authentication mechanism. And it’s the default for a good reason: it complicates shoulder-surfing attacks with a minimal impact on usability.
2. He also argues that displaying passwords in plaintext will increase a user’s confidence, leading to increased security because the user will choose a longer password. However, in a past article, Nielsen also claimed it is a lie that “long passwords are more secure than short ones”, and declared unequivocally that “users write down their passwords”. You can’t have it both ways, Jakob.
3. For a log-in form to display the password in the clear is not the expected system behavior, and this is bad for usability. Nielsen suggests that a site could provide a check-box to enable password masking. Having to click a button to get the desired default behavior is also terrible for usability.

Perhaps the most egregious error in all the article is this gem:

More importantly, there’s usually nobody looking over your shoulder when you log in to a website. It’s just you, sitting all alone in your office, suffering reduced usability to protect against a non-issue.

In the real world, people work in open offices, log-in to websites during presentations, browse the web with their significant-others, and expect websites to respect their privacy. But I will concede that in Jakob Nielsen’s private office, on the penthouse floor of his ivory tower, password masking is probably useless.

Some enterprising hacker quickly seized the opportunity to promote Twitter-clone StalkDaily by infecting the profiles of hundreds of users, and using their accounts to Tweet marketing messages such as “Join www.StalkDaily.com everyone!”. StalkDaily denies any responsibility for the XSS attack. The source-code for the worm is available, and reveals just how simple this attack really was.

Here is a little free advice for the developers at Twitter: install xss-shield, or start using h() to escape user-supplied strings in your templates. Since the field that was vulnerable to cross-site scripting and allowed this worm to propogate was supposed to be a URL, it might not hurt to validate that against a simple regular expression while you’re at it.

I’ve lost count of the number of security breaches Twitter has had in the past few months. The question now is whether they’ll hire a competent web security architect and clean-up their act.