Is Battery-Free 2-Factor ID Secure? 180
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?"
Think I'll pass (Score:2, Insightful)
Let's see. Worst case scenario, you set up a camera that does about 30fps, with rotating filters in front, and use OCR to look for text in each frame. 30 passwords per second is a lot faster than 1 password + delay, 2 password + longer delay, 3 password + get account re-enabled.
Aside from that brute force method, I suspect the system is pretty vulnerable to more sophisticated attacks, like quickly narrowing down what window people have by analysing the more obvious features (number of lines, angle of lines, ratio of vertical lines to horizontal waves, etc.) of an on-screen pattern, for instance.
Basically... donotwant.
Prior Art (Score:5, Insightful)
One major problem: monitor resolution (Score:5, Insightful)
A lot of these sorts of schemes assume some sort of fixed pixel size such as 96 dpi, a fantasy that hasn't been true since, well, ages. Some LED screens have up to 150 dpi resolution, others as low as 72dpi. If the scale is wrong, then the pixels won't line up and the decoder is then useless.
Now, I admit it's possible that the creator of this scheme might have solved this, but I doubt it. A colour filter like those games whose clues are read through a red plastic foil viewer would be far too easy to crack, for example.
I can't escape the impression that this is just security theatre and not serious security after all.
Er, WTF? (Score:3, Insightful)
So you are worried about crackers breaking into your house and setting up spy cams to steal your banking password?
If they have already broken into your house why would they bother with that? Why not just steal your statements?
Or just use the spy cams to record all your online activity?
Talk about paranoid. This is a pointless argument against the system that holds no merit at all.
Chaum-like (Score:5, Insightful)
This is sort of like one of Chaum's voting system reciepts. those are provably secure for single use.
however having watched the video, it's obvious this one is weakly secure for a single use and rapidly insecure for multiple uses.
given a series of challenges one should be able to apply a process of elimination to determine the missing elements.
the alternative would seem to be to choose the challenge from a restricted pallet of challenges that assures some ambiguity. in this case intercepting a bunch of challenges will simply reduce the number of possible choices.
for example, if the ambiguity could be maintained at 3 choices per digit then 7 digits provides 2187 possiblilites.
that's actually not hideous. it's comparable to a bicycle lock. thus the key to making that low number useful is to prevent someone from rapidly trying the challenges exhaustively.
e.g. if you are only allowed 2 challenges per 30 minutes, or more deviously, if the challenger denies access with say 10% probability even when you type in the right pass code.
this will make such 2- factor while not government grade probably not worth the attackers time.
Re:Easily Rectified (Score:3, Insightful)
This image [resized using point, inch, or other physically-based CSS units] is going to be scaled to be the exact same size on the screen in any web browser.
Unless the operating system's DPI setting doesn't match the physical dimensions of the monitor. A lot of people have never taken a ruler to their monitors, and some poorly-written yet business-critical applications for Windows tend to barf at any DPI setting other than 96.
Security for the masses (Score:4, Insightful)
Most of the comments here are aimed at high-security applications where the assumption is that there are people looking to crack the security and will do whatever it takes to do so. This invention isn't targeted at that application however. You've missed the point.
This security is like a standard car door lock or home door lock. It won't prevent someone from breaking in but it will deter them enough to make it a less attractive. This certainly shouldn't be used to protect your bank account but it could be used the authenticate you on a variety of websites that do not hold any sensitive information (you'd still need your CC number to make a purchase) or as a guest key to get access to a wireless connection at a cafe.
As a light security measure this is a fairly good option... just like a key/lock as described in the video.
The big point is that a criminal would have to work fairly hard to get access to an account, without knowing if the amount of work involved will be rewarded and this amount of work would have to be repeated for each account.
Re:Easily Rectified (Score:3, Insightful)
You must not do a lot of CSS coding, or deal with multiple monitors. One centimetre on one screen is not the same on another. The usage of Pica, inches, millimetres and so on is only really recommended for print use. When used with screen resolutions, they are calculated into pixels based on the browser's preferences (often only switchable between 72dpi and 96dpi).
Even on prepress monitors, I have yet to see a monitor where a centimetre on the screen is equal to a centimetre on a ruler held to the screen.
Re:Easily Rectified (Score:1, Insightful)
No, the image will not be scaled to match the specified dimensions.
The OS may believe it knows the dimensions of the actual display, but that information does not have to be accurate at all (e.g. my OS thinks it's showing /. on a 17" instead of the 19" that is connected)
On top of that, one can easily change the size of the display area (at least on CRTs) using the various dials on the monitor for stretching or squeezing the visible screen display.
WATCH THE VIDEO (Score:3, Insightful)
1. The security card is extremely cheap, looks it, and like all such cheap security measures, easy to crack. It was designed to be built into a MasteCard (at basically less than $1 per card), not built into your top secret government code-key.
2. It is not intended as the kind of super-secret security. It is CHEAP security - like one of those chains you put on your front door. It doesn't keep the mafia out, it keeps the obnoxious delivery boy out.
3. If used properly, it can prevent the kind of fraud it is intended to prevent - when Amazon mistakenly sells a hard drive full of your credit card numbers that the morons forgot to encrypt, they will skip your credit card number because it is NOT worth the trouble to deal with the code, especailly when a bunch of other credit card companies don't use the security.
4. This is a great form of CHEAP security, and if all you want is CHEAP security, then it is well worth it.
Re:My microwave is Passwindow protected. (Score:3, Insightful)
The same is true for Passwindow. I bet that with 5-10 instances of ciphertext and the knowledge that the cleartext is a numeric code, you could work out the key.
So what? Getting 5 - 10 instances of the ciphertext is a barrier to entry that PassWindow provides. Is it uncrackable? Of course not. But then again, what is?
If you lock the door of your house or your car, you should take PassWindow seriously, because clearly you believe that "trivially breakable security is better than none." If you didn't, you'd leave your house and car unlocked.
Fallacy (Score:1, Insightful)
The power source should not be considered in the security question. That is a reliability and availability issue. With "soft tokens" that can be safely operated from phones and USB thumbdrives, there are already solutions to the perceived problem.
Now, to address the question of security for this new "token", you need to focus on the PIN generation algorithm, and the security of the delivery channel.
Unfortunately in this little PR video, there's not enough technical implementation information to make any deeper analysis of the specific solution. But we can speculate on this type of system, in general.
Obviously, the SecureID type token - where no secret is transmitted to generate the secret - is always more secure than a scheme where a remote display of a secret is generated. The channel can be intercepted enroute, if valuable enough to warrant the effort. There is also the possibility of TEMPEST type attacks on monitor emissions. These have to be evaluated, but I expect they are low-risk, and with the one-time use of the secret, probably not worth the trouble.
More troubling? This is being generated and displayed on demand, when regular credentials are first supplied. That means that an attacker with the regular password can request a new PIN many times, regardless of thier location. They can do this many times, and analyze output well enough to craft an attack on the scheme.
Ultimately, I would view this as a replacement for CAPTCHA technology, which it more closely resembles, than I would an improvement on OTP tokens. Unfortunately, I don't see the value of CAPTCHA justifying the cost and effort in this "passive" OTP.
Re:Er, WTF? (Score:4, Insightful)
No, I'm worried that the planet will be overrunby self-assured neanderthals who can't think of a situation other than home banking in which an authentication system might be used.
Even neanderthals know that regardless of the application, if someone has acquired physical access to your home you're pretty much fucked.
If you can't make use of controlled paranoia, you've no business discussing security issues.
Great, let's control this paranoia with some rational assessment. So, we've got a plastic window that acts as a filter on random data. How does this compare to a typical 2-factor solution, the RSA SecurID? An attacker needs both the random data and the window pattern to get the true passcode. We can assume they can snoop the random data, so then if they can see the window (somehow) they can crack it, but if they can see a plastic window it's not too much of a stretch to them being able to see your dongle's display. RSA has an advantage here, but not one a paranoid person would be moved by.
Now perhaps the attacker can reverse-engineer the pattern by tricking them into visiting a phishing site and see what tokens they enter for a given piece of random data. Without doing the math, it seems like it would take a small-ish number of tries to deduce the pattern (since we're only talking about seven segment digits here), but probably more than a normal user would expect to be able to try without being locked out of the system. If they do discover the window, then they have broken the scheme completely. Compare to SecurID, where it would be intractable to figure out the random seed based solely on the tokens generated. On the other hand, in both cases it only takes entering in a password/token combo into a phishing site once and the attacker then has a valid password for as long as that code is valid -- ~30s on a SecurID, more than long enough to gain access to the protected system.
Thus the plastic window method is more likely to result in giving an attacker long-term access, but only in situations where a SecurID would likely have given an attacker access at least once. While certainly there are cases where the former is worse, in general having an attacker gain entry even once is unacceptable.
So while it's not a direct 1:1 replacement for SecurID, it isn't all that much worse, and much better than 1-factor authentication. As a low-cost way of adding additional security this is a pretty damn good invention. There are many applications where this will be more than good enough. Home banking being one, yes. For, say, the FBI agent logging into work it may not be, but they can keep their SecurID or whatever they use, if they decide there's a point.
Multi-factor authentication -- something you have (Score:3, Insightful)
How is this more secure than a key? Like an honest-to-goodness, metal-object-you-stick-in-a-lock, physical key?
It's not. It's not really trying to be. It is, in fact, supposed to be the online equivalent of a key, a physical device which you have to possess in order to gain access to something.
Haven't there been tons of discussions about why using flash drives to store passwords is a really bad idea, simply because the risk to your physical media being stolen is much higher than the risk of your passwords being divulged?
The idea here is to use both -- "something you know" in your password, and "something you have" in the PassWindow, and you combine your password plus the random number into a single larger password. The idea is that if one component is compromised, that still doesn't give them the other. Imagine you had both a keyed dead bolt and a combination lock on the door to your house. To get in, someone would have to snoop you entering in the code, and then steal your keys. If you dropped your key and someone picked it up, you wouldn't have to worry about them getting in if they hadn't seen your passcode, and vice versa.
but does it do anything to prevent social engineering the way a strong password or PIN does?
Strong passwords don't prevent social engineering, they prevent dictionary and other simpler-than-brute-force attacks. But if someone lures you to a malicious website that looks like the one you want to log in to, and you type in your password, you're hosed. With this and SecurID style multi-factor authentication, this risk is still there. If you type in your password+random# combo into the evil web page, then they have access for as long as that random # remains valid.