What qualifies as a safe and sane password policy for your business? A recent blog post serves up some interesting answers to this question.This week, blogger Paul Rubens raises a very relevant security issue: Does size matter when it comes to choosing a password or enforcing a corporate password policy. The answer, of course, is yes -- but as Rubens points out, an obsession with "tough" passwords may simply provide a band-aid that conceals other, potentially more serious, security issues: A healthy dose of realism is clearly in order. "A lot of guidance about password length and complexity is just a sticking plaster over an underlying problem with passwords," says Dr Ant Allan, a research vice president at Gartner. "It's important to remember that if you increase length or complexity you are only defending against some kinds of attacks anyway," he says. "If the end user's machine is infected with spyware then the password will still be discovered, regardless. And a long password does nothing to prevent a hacker getting a password using social engineering. These types of policies are beloved of auditors, trotting out established ideas." Rubens also notes that other common password security measures are far less effective than they seem to be. Policies that require users to change their passwords every few months are a great example: While this does not give an attacker nearly enough time to crack a strong password using brute-force methods, it provides way too much time for an attacker that gets a password using other means (such as spyware or a social-engineering hack) to run amok on a company's systems.

And what about those invulnerable monster passwords? The certainly are hard to crack: According to Rubens, a 15-character password could take up to two trillion years to crack, using existing mainstream computing technology. On the other hand, long passwords encourage users who lack a photographic memory to cut corners; I recall one example involving a former co-worker who kept his laptop password written down on a piece of paper -- and who like to keep this reminder not-so-safely tucked away in his laptop carrying case!

If that sounds like a familiar problem, be sure to check out Rubens' next blog entry, where he discusses an important way to balance password security and usability: password management tools.