[HN Gopher] The Plausibly Deniable DataBase (PDDB)
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The Plausibly Deniable DataBase (PDDB)
Author : sohkamyung
Score : 89 points
Date : 2022-02-08 11:03 UTC (11 hours ago)
(HTM) web link (www.bunniestudios.com)
(TXT) w3m dump (www.bunniestudios.com)
| TacticalCoder wrote:
| This "$5 wrench" XKCD always come up but... Plausible deniability
| ain't the only way around it.
|
| For example there are safes that, no matter what you do, are only
| ever going to open on, say, wednesday morning at 10am. Or a safe
| that shall only open if, one hour previous to that, you entered
| your own personal code + a rolling code. You enter the rolling
| code and the one-hour countdown starts. Now... If you can only
| get the rolling code by calling someone (for example a security
| company) and if that person accepts two words, one being the real
| one, the other the "I'm under duress" one, now suddenly the "$5
| wrench attack" doesn't look that great anymore.
|
| BTW my home alarm has something similar: they'll came me after
| either a break-in or if I push the button "I'm under attack"...
| Then through the speakers they'll ask me "the" word. No matter if
| I say "banana" or "potato", they'll answer: all is fine, good
| night. But... "banana" means "everything is cool" while "potato"
| means "I'm under duress". Cops show up in 120 seconds where I
| live. The $5 wrench dudes better make very good use of that $5
| wrench that'll, for sure, bring them billions of $$$ (such
| intelligent human beings btw: they figured out that a $5 wrench
| shall bring them riches) because in 120 seconds the cops are
| going to be there.
|
| Back to the safe: the countdown starts and the attacker has no
| clue if the police has been contacted. They have to wait one
| hour. Oh and both codes starts the countdown. But the "I'm under
| duress one" will lead to some failure message on the safe "Error:
| mechanism locked" or "Bug 2134978" (whatever fancy you can come
| up with).
|
| A $5 wrench attack is one thing. Kidnapping someone for days is
| another thing. Waiting for a safe to open for one hour without
| knowing if the cops are on their way (and have one hour to be
| there) is yet another thing.
|
| My point is: I'm a bit fed up by people who have the victim
| mentality and think nothing can be done versus attackers. If
| attackers were that smart, they wouldn't be doing $5 wrench
| attacks in the first place. Use your intelligence to come up with
| schemes that a $5 wrench attack cannot break.
|
| Another good one: a safe which only opens after a countdown of
| one-hour, no other way round. But as soon as you enter the code
| (and the countdown starts), a video feed of the room where the
| safe is located is sent to a security company. Someone at the
| security company checks the feed: he sees the $5 wrench (or he
| sees two people in the room, which is forbidden)... He calls the
| police and the police has one room to get the dude with the $5
| wrench.
|
| I much prefer people who think not just about how to resist $5
| wrench attack but who thinks about ways to maximize the chance
| the one holding the $5 wrench ends up where he belongs.
|
| So yup: I'm a bit pissed by that $5 wrench XKCD. So pissed I may
| actually one day join forces with company working on solutions to
| fight against that.
| HideousKojima wrote:
| >Cops show up in 120 seconds where I live.
|
| Sorry to nitpick a single sentence out of your entire post, but
| where in the world do you live that has a response time like
| that? I wouldn't expect that kind of response time even if I
| lived next door to a police station. Hell I'd be doubtful of
| getting a response time like that if my spouse was an on-duty
| cop and was home when the attack occurred.
| supersell wrote:
| Prison
| mortehu wrote:
| I've called police for ongoing violence twice, and in both
| cases the response time was shorter than this. This is one
| thing the police really knows how to do.
|
| See also https://leb.fbi.gov/image-repository/police-
| response-time-to... which has the median response time to
| active shooter situations at 3 minutes
| remram wrote:
| Then the attacker kidnap _your kid_ , and you go through the
| entire procedure correctly the next day and give them the data.
|
| However comprehensive your security procedure is, so long as a
| human can unlock it, your data is not secure. That's the point
| of the xkcd, not the specific wrench.
| 2fast4you wrote:
| You're assuming the attacker needs to be in the room with you,
| coercing you directly.
|
| Imagine this: an attacker has something against you. Maybe they
| know a secret you don't want getting out, maybe they've
| kidnapped a loved one, etc. The attacker has threatened you and
| shown proof of the threat all with coming face to face. They
| now demand you give up the contents of the safe as ransom.
|
| How is your time delay and secret code words gonna help?
| cryptonector wrote:
| Safes are rated in time to breach. They can all be breached.
| Revealing a duress code will not achieve anything unless the
| attacker is running _your_ code (why would they), and if they
| 're not, it will produce insufficient quantities of meaningful
| plaintext, leading to... more torture.
|
| Repeat after me: cryptography cannot be the rubber hose.
| dumbfounder wrote:
| I have discussed another way to solve some of the same problems,
| especially as it relates to crypto wallets. You need to have some
| way to prove that you cannot access the data, guaranteeing that
| torture to be ineffective.
| rootsudo wrote:
| I guess everyone already had forgotten the truecrypt fisaco.
| Zarkonnen wrote:
| This is more or less the same thing as a steganographic file
| system, I think?
| https://en.wikipedia.org/wiki/Steganographic_file_system
| remram wrote:
| This is _only_ a steganographic file system. If someone finds
| your secret, there 's nothing deniable about it. Hidden is
| different from deniable.
|
| If you're trying to hide the entire fact that there is secret,
| encrypted data on your secret-encrypting device/drive, I am not
| sure I get it either.
| MauranKilom wrote:
| ...but using specialized PD software in plain sight like this
| more or less defeats its point, no?
| mLuby wrote:
| It's useful as a demonstration. More popular databases might
| see this and decide to include the feature as well. The best
| case would be if, say, Apple included a plausibly deniable file
| system or database _by default_ on their systems. Now that even
| your grandma has it, its presence can 't signal a secret.
| hbrav wrote:
| This probably depends on where you are using it. If I
| understand correctly, it tells an attacker that you have
| _something_ to hide, but gives no clue as to any metadata, such
| as the size of what you're hiding or how often it was updated.
|
| Suppose a government agency is demanding that you decrypt...
| something, they're not sure what, or how much there is, or even
| if there's anything there. In a country with a strong rule-of-
| law, I think you're unlikely to have a court enforce sanctions
| against you to make you produce cleartext _that may not even
| exit_, unless they have very strong evidence from another
| source that it does exist. If you're in a more authoritarian
| country where the police can hold you for a long time just on
| the off-chance that there's more cleartext to get, then I don't
| think this helps you much.
|
| Actually, I think we can maybe summarize: you probably
| shouldn't use this to defend against someone who would have no
| qualms just straight-up torturing you.
| gampleman wrote:
| It could even make things _much_ worse for you. If you have a
| standard encryption scheme then the torturer can be
| reasonably sure that they got everything useful out of you
| and can stop torturing you.
|
| On the other hand if you are running PD software, then even
| if you had nothing particularly important to hide (gasp, they
| now have my Facebook password!), they might as well continue
| torturing you since there is no way to show that really you
| don't have those stolen Death Star plans.
| pessimizer wrote:
| The problem with torture is that in that case you also have
| no reason to give them a correct answer, no matter how much
| they hurt you.
| cryptonector wrote:
| That's not the case here.
|
| Here they have a way to confirm that what you gave them
| produced more meaningful plaintext. And considering how
| large this PDDB might be, you might never be able to give
| them enough passwords to produce as much meaningful
| plaintext as could have been stored in it. Therefore they
| might never be satisfied that you have produced _all_ of
| the meaningful plaintext plausibly stored in the PDDB.
|
| You might as well say that giving the user plausible
| deniability also means giving their adversary plausible
| never-reaching-the-end-of-the-barrel. The former is good
| for the user _if and only if_ the adversary is willing to
| pretend the PDDB thing isn 't a thing, but why would
| they?
|
| No, plausible deniability tools are not useful to most
| users. They are plausibly useful to a class of users
| (spies?) who might have resources or recourse to leverage
| that can be used to a) get them set free, b) without much
| or any torture, and c) without having to reveal their
| secrets. That class of users must be very small.
| arcticbull wrote:
| > This probably depends on where you are using it. If I
| understand correctly, it tells an attacker that you have
| _something_ to hide, but gives no clue as to any metadata,
| such as the size of what you're hiding or how often it was
| updated.
|
| Which brings you right back to the problem illustrated in the
| XKCD comic up top. As soon as you know they have something to
| hide you whack them until they tell you.
| dividedbyzero wrote:
| Depending on where you are and what specific laws are in
| place that someone (the police maybe?) may not be able to
| get more whacking past a judge. I think this could work
| reasonably well in such situations.
| arcticbull wrote:
| Here's the problem. In a rule of law jurisdiction there's
| no value provided. In one without they'll just hit you.
| throwaway22032 wrote:
| So you tell them.
|
| How do they know you've told them everything?
| arcticbull wrote:
| Whack harder.
| [deleted]
| giaour wrote:
| There is still some value in being able to disclose some
| private data without disclosing whether further private
| data exists. The other party will not know after a
| revelation if they have obtained the totality of secret
| data and must decide whether to continue to hit you with
| the wrench on the off chance that more secret data exists.
|
| This is a well known dilemma when interrogating people,
| since there's no known metadata about how many facts exist
| in your brain. As the GP points out, though, a common
| authoritarian response to this dilemma is to just keep
| torturing.
| ansible wrote:
| I agree with all that.
|
| The only way something like PDDB would work in practice to
| help the people intended, is for the software to become
| _very_ widely used. For example, where everyone stores their
| pornography in a PDDB.
|
| In that case, you would also store some porn in your PDDB,
| and would give up the password to that with little coercion.
| If they can't then prove the existence of more information,
| then you _might_ be let go without too much damage.
|
| Obviously, you shouldn't be storing porn that is illegal in
| your (or most other) jurisdictions in the first level of your
| PDDB.
|
| In any event, good luck trying to get even a fraction of
| normal users to install and use this software. Even if all
| the Linux distros include it by default, I don't think that
| would be enough, that would just widen the target to "all
| Linux users" in oppressive country A.
| cryptonector wrote:
| Widespread use does not help the user: whoever wants their
| secrets will still insist on production of ever more
| secrets whenever the user is found to be using a PDDB.
|
| Widespread use can only help if that widespread use leads
| the State to accept it and that it should not insist on
| production of secrets from PDDBs. However, how likely do
| you think that would be??
| abecedarius wrote:
| Only under the assumption of no legitimate reasons for privacy.
| Is using https evidence that you're a criminal?
| bunnie wrote:
| The idea is that it would be the only form of storage on the
| device, so it wouldn't be specialized. That's how it is
| implemented on Precursor -- you don't have a parallel non-
| deniable storage, and then a deniable one. Everything goes into
| one bin for everyone.
| foxfluff wrote:
| One possible approach to the free space issue on a laptop could
| be (encrypted) swap. If the system is configured to allocate swap
| pages in order and you have appropriate limits in place, the
| likelihood that you reach 100% swap usage can approach zero (but
| is hard to prove). Use the free space at end of your swap for
| secrets. Having multiple swap files / swap partitions that you
| activate when you need more memory for compiling Firefox would
| give further proof against accidentally overwriting your secrets.
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