Passwords are hard. To be useful, they must be hard to guess. But the rules we put in place to make them hard to guess also make them hard to remember. So people do the minimum they can get away with.
Earlier this week, security company Webroot took a look at the unintended consequences of password constraints. The rules organizations set in order to ensure passwords are sufficiently complex reduce the total number of possible passwords. This can make automated password guessing more
Good passwords are easy for the user to remember and hard for computers and other humans to guess. Let’s say I wanted to use a password like
2Clippy2Furious!! Various password checking sites rate it highly. It’s 18 characters long and contains upper- and lower-case letters, digits, and special characters. But because it contains consecutive repeating letters, some companies won’t allow it.
Writing for Webroot, Randy Abrams says “it’s length, not complexity that matters.” And he’s right. That’s the point behind the “correct horse battery staple” password in XKCD #936. So let’s all do that, right?
Well…it’s not so simple. If I were trying to brute force passwords, and I knew everyone was using four (or five or six) words, suddenly instead of “CorrectHorseBatteryStaple” being 26 characters, it’s four. Granted, the character set goes from 95 to (using
/usr/share/dict/words on my laptop) 479,828. “CorrectHorseBatteryStaple” is many powers of 10 more secure if the attacker doesn’t know you’re using words.
And let’s be real: they don’t. This hypothetical weakness has a long time before it becomes a real concern. Don’t believe me? Just look at the password dumps when a site gets hacked. There are a lot of really bad passwords out there. If we took all the constraints off (except for minimum length), people would just use really dumb, easily-guessed passwords again. But it amuses me that if everyone followed good password advice, we’d actually make it worse for ourselves. Passwords are hard.
Sidebar: Yes, I know
The savvier among you probably read this and thought “it’s better to use a random string that you never have to memorize because your password manager handles it for you. Just set a very long and memorable password on that and you’re good to go.” Yes, you’re right. But people, even those who use password managers, will often go to memorable passwords for low-risk sites or passwords they have to use often (e.g. to log in to their computer so they can access the password manager).