Is Battery-Free 2-Factor ID Secure?

An anonymous reader writes "There was a television program in Australia last week about Matthew Walker's visual battery-less two-factor authentication system called PassWindow. Essentially, you hold the clear plastic window up to the apparently random pattern on the screen of your computer, revealing a one-time PIN to type in for authentication. The plastic window has many advantages: difficult to copy or view over the shoulder, etc. Because there is no electronics, chip or battery, the PassWindow is extremely cheap to manufacture, giving it a big advantage over other two-factor authentication systems. However, I don't know about the security of the system. The apparently random pattern of lines in the PassWindow is analogous to a one-time pad, using a different subset of the one-time pad every time a PIN is needed. Is this a useful level of security for logging in to a bank account?"

Comments

meh

[TheSHAD0W]

From what I saw, this system might be able to protect you from a single compromisation of your security. This would depend on a few factors, though. Given you can see both the pattern and the code, from a single session you could make some assumptions about what the code would be with a different pattern. It might take a few tries to generate the correct code. If the attacker can partially log in multiple times without being locked out, he may be able to choose a pattern that has fewer possible permutations for the code.

There's also a potential problem in that, if an attack is made on an account and the account is locked out, the card would have to be replaced. Otherwise, if the account is re-enabled without replacing the card, the attacker would be able to continue to make attempts to log in. I suppose you could also alert the customer to change their password due to a security breach.

I don't think this will protect very well against a customer's own system being compromised, with an attacker being able to monitor multiple log-ons. There are simply too few possible permutations in those 7-segment displays.

I'd also like to mention there's a potential problem if the monitor's resolution is too high. If, for instance, the user wants to log on via a netbook, the code displayed may be too small to match up with the code on the card, making logging in impossible.