CronoDAS comments on [LINK] Using procedural memory to thwart "rubber-hose cryptanalysis" - Less Wrong

3 Post author: shminux 19 July 2012 11:54PM

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Comment author: CronoDAS 20 July 2012 12:33:52AM 13 points [-]

Even if you can't divulge the password, you can still enter it... so if someone is actually in a position to coerce you, they're probably also in a position to make you enter the password for them. (It's damn hard to make an ATM that will give you your money when you want it, but also makes it impossible for someone to empty your account by waiting for you at the ATM and pointing a gun at you.)

Comment author: VNKKET 20 July 2012 02:08:35AM *  5 points [-]

And after skimming the paper, the only thing I could find in response to your point is:

Coercion detection. Since our aim is to prevent users from effectively transmitting the ability to authenticate to others, there remains an attack where an adversary coerces a user to authenticate while they are under adversary control. It is possible to reduce the effectiveness of this technique if the system could detect if the user is under duress. Some behaviors such as timed responses to stimuli may detectably change when the user is under duress. Alternately, we might imagine other modes of detection of duress, including video monitoring, voice stress detection, and skin conductance monitoring [8, 16, 1]. The idea here would be to detect by out-of-band techniques the effects of coercion. Together with in-band detection of altered performance, we may be able to reliably detect coerced users.

Comment author: Kaj_Sotala 20 July 2012 08:42:10AM *  12 points [-]

Of course, such changes could also be caused by being stressed in general. Even if you could calibrate your model to separate the effects of "being under duress" from "being generally stressed" in a particular subject, I would presume that there's too much variability in people that you could do this reliably for everyone.

Imagine how people would react to an ATM that gave them their money whenever they wanted it - except when they were in a big hurry and really needed the cash now.

Comment author: handoflixue 24 July 2012 11:10:08PM 0 points [-]

(Blind Optimism) They'd learn to meditate!

But then, how do we stop people from being coerced in to meditative states... :(

Comment author: ViEtArmis 20 July 2012 02:43:25PM 2 points [-]

Got the flu? Sorry, no email for you today.

Comment author: jimmy 20 July 2012 07:47:05PM 2 points [-]

My next step would be to game context dependent memory to make the memory unavailable under duress.

Comment author: [deleted] 20 July 2012 10:20:13PM 2 points [-]

I've heard of some kind of security system whereas you can enter either the usual password or a “special” one, and if you enter the latter you're granted access but the police are alerted, or something like that.

The extension to that to an ATM might be one which gives fake bills, takes a picture, and alerts the police if the “fake” PIN is input.

Comment author: VincentYu 21 July 2012 02:33:59AM 1 point [-]

For ATMs, the idea is out there, but it has never been implemented. Snopes on this:

The Credit Card Accountability Responsibility and Disclosure Act of 2009 compelled the Federal Trade Commission to provide an analysis of any technology, either then currently available or under development, which would allow a distressed ATM user to send an electronic alert to a law enforcement agency. The following statements were made in the FTC's April 2010 report in response to that requirement:

FTC staff learned that emergency-PIN technologies have never been deployed at any ATMs.

The respondent banks reported that none of their ATMs currently have installed, or have ever had installed, an emergency-PIN system of any sort. The ATM manufacturer Diebold confirms that, to its knowledge, no ATMs have or have had an emergency-PIN system.

Comment author: JackV 20 July 2012 11:18:15AM 1 point [-]

I don't know if the idea works in general, but if it works as described I think it would still be useful even if it doesn't meet this objection. I don't forsee any authentication system which can distinguish between "user wants money" and "user has been blackmailed to say they want money as convincingly as possible and not to trigger any hidden panic buttons", but even if it doesn't, a password you can't tell someone would still be more secure because:

  • you're not vulnerable to people ringing you up and asking what your password is for a security audit, unless they can persaude you to log on to the system for them
  • you're not vulnerable to being kidnapped and coerced remotely, you have to be coerced wherever the log-on system is

I think the "stress detector" idea is one that is unlikely to work unless someone works on it specifically to tell the difference between "hurried" and "coerced", but I don't think the system is useless because it doesn't solve every problem at once.

OTOH, there are downsides to being too secure: you're less likely to be kidnapped, but it's likely to be worse if you ARE.

Comment author: printing-spoon 21 July 2012 05:33:54AM 0 points [-]

you're not vulnerable to people ringing you up and asking what your password is for a security audit, unless they can persaude you to log on to the system for them

Easier to avoid with basic instruction.

you're not vulnerable to being kidnapped and coerced remotely, you have to be coerced wherever the log-on system is

Enemy knows the system, they can copy the login system in your cell.

Comment author: billswift 20 July 2012 12:55:21PM 0 points [-]

OTOH, there are downsides to being too secure: you're less likely to be kidnapped, but it's likely to be worse if you ARE.

Indeed, for a recent, real world example, the improvement in systems to make cars harder to steal led directly to the rise of carjacking in the 1990s.

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