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The Futility of Lava Lamps: What Random Means

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Re: The Futility of Lava Lamps: What Random Means

#51

Post by AlotOfReading »

dheera wrote: post #29
AlotOfReading wrote: post #9

Earlier quoted context omitted.

Smashing the glass wouldn't make it less effective. The sensor itself has noise, and the camera output is fed into an HMAC with a key based on the current nanosecond before being combined with a traditional entropy source before it ever went anywhere. Even then, it was only used as a seed for the entropy pool on the actual server.

> and the camera output is fed into snip snip ?

You still wouldn't be about to distinguish the output from noise unless you know the key or you've broken the cryptography, even if you know every bit of the message. Isn't it neat?

And yes, as the other comment points out it's only one source among multiple.

Re: The Futility of Lava Lamps: What Random Means

#52

Post by mock-possum »

NuclearPM wrote: post #31
__MatrixMan__ wrote: post #25

Nothing is random enough for an arbitrary audience. There's always the possibility that some alien spaceship will land and some creature will emerge, take a glance at your RNG, and say: "next one's 6598489811, try it" and they'll be right. We can only say that something is random enough given a certain audience's beliefs about what kind of predictions are possible. If it takes lava lamps to convince that audience, we…

Why would beliefs matter?

Because the judgment of what counts as ‘enough’ is tied to beliefs

Re: The Futility of Lava Lamps: What Random Means

#53

Post by Retr0id »

Retr0id wrote: post #6

> And if it is broken… then you’re screwed, sorry. See, both your encryption and your CSPRNG relies on a cipher. If either is broken, then so is your whole system. Not necessarily . The CSPRNG state could in theory be leaked via sidechannels. Your cipher key could be leaked via sidechannels too, but symmetric encryption keys tend to be shorter lived.

Another "why on earth are HN users downvoting this?" moment...

Re: The Futility of Lava Lamps: What Random Means

#54

Post by ykonstant »

b65e8bee43c2ed0 wrote: post #15
JKCalhoun wrote: post #5

With a one-time pad being, as I understand it, the only really good encryption, I am surprised there is not a market for pairs of matched hard drives—the pair having the same "one time pad" stored on them (how you generate those numbers is left as an exercise for the company marketing them). A simple app could be used by parties on both ends of the message—an app that relies on an associated drive to act as the pad.…

the reason why there isn't a market for such drives is that someone who needs that level of security rightfully wouldn't trust any entity to 1. generate truly random data, which is required for OTP to be perfect 2. not store a copy of the data to be handed over to bioluminescent individuals at the drop of a hat

>bioluminescent individuals

Brilliant.

Re: The Futility of Lava Lamps: What Random Means

#55

Post by dpark »

Terr_ wrote: post #47
tptacek wrote: post #46

Earlier quoted context omitted.

I'm sorry, I've lost track of what you're trying to argue. The point is that in practice, any sane design is just going to hash "lava lamp" information in with all the other low-quality entropy inputs that drive the LRNG. I wasn't making a subtle or complicated point here.

I'm not making a subtle or complicated point either. I think the start of it is that we had different ideas of what "worse" was being compared to. You're saying "It's hard to tell a story where the wall is making things worse [compared to replacing it with nothing]." If the initially-unspoken bracketed condition is added, then yes, I agree with you. My response was: "There might be a story where the wall is making th…

The issue is that your “compared to other things” essentially requires CloudFlare to be incompetent which, sure, that could be a thing. But then there are bigger problems.

None of your concerns hold up to scrutiny. Using lava lamps instead of better sources of entropy implies incompetence. CloudFlare is also not so resource limited that they can’t dump the lava lamp entropy in with the rest of their entropy sources. Or else, again, incompetence.

Re: The Futility of Lava Lamps: What Random Means

#56

Post by akerl_ »

Terr_ wrote: post #47
tptacek wrote: post #46

Earlier quoted context omitted.

I'm sorry, I've lost track of what you're trying to argue. The point is that in practice, any sane design is just going to hash "lava lamp" information in with all the other low-quality entropy inputs that drive the LRNG. I wasn't making a subtle or complicated point here.

I'm not making a subtle or complicated point either. I think the start of it is that we had different ideas of what "worse" was being compared to. You're saying "It's hard to tell a story where the wall is making things worse [compared to replacing it with nothing]." If the initially-unspoken bracketed condition is added, then yes, I agree with you. My response was: "There might be a story where the wall is making th…

The entire premise of modern CSPRNGs is that you feed into them whatever entropy sources you have, wherever it's from, the more the better.

The point of disagreement here, about whether or not it's possible that they'd be choosing to use the lava lamps to the exclusion of some better source, doesn't make any sense against that framing.

Re: The Futility of Lava Lamps: What Random Means

#57

Post by __MatrixMan__ »

NuclearPM wrote: post #31
__MatrixMan__ wrote: post #25

Nothing is random enough for an arbitrary audience. There's always the possibility that some alien spaceship will land and some creature will emerge, take a glance at your RNG, and say: "next one's 6598489811, try it" and they'll be right. We can only say that something is random enough given a certain audience's beliefs about what kind of predictions are possible. If it takes lava lamps to convince that audience, we…

Why would beliefs matter?

Beliefs drive our actions, even when they're about unknowable things. Whether or not something is random is unknowable, so belief is all we have.

We may discover tomorrow that events which we previously thought were random, like the timing of a single atom's radioactive decay, are actually perfectly predictable. If we believe that such a discovery is unlikely then we might trust radioactive decay as an entropy source, and if we believe its very likely then we probably won't.

Re: The Futility of Lava Lamps: What Random Means

#58

Post by JKCalhoun »

DevelopingElk wrote: post #26
JKCalhoun wrote: post #5

With a one-time pad being, as I understand it, the only really good encryption, I am surprised there is not a market for pairs of matched hard drives—the pair having the same "one time pad" stored on them (how you generate those numbers is left as an exercise for the company marketing them). A simple app could be used by parties on both ends of the message—an app that relies on an associated drive to act as the pad.…

Russian one time pads were frequently broken. How? They were inconvenient to distribute, so people reused them. Symmetric cryptography is safer because one key can easily protect as much data as you need.

I would think that a 10TB one-time pad (for example) would probably never get "used up".

Re: The Futility of Lava Lamps: What Random Means

#59

Post by JKCalhoun »

marshray wrote: post #10
JKCalhoun wrote: post #5

With a one-time pad being, as I understand it, the only really good encryption, I am surprised there is not a market for pairs of matched hard drives—the pair having the same "one time pad" stored on them (how you generate those numbers is left as an exercise for the company marketing them). A simple app could be used by parties on both ends of the message—an app that relies on an associated drive to act as the pad.…

I've heard it said that such systems may be used by militaries, where they have an organizational structure naturally-suited to large keystream distribution. Unlike e-commerce, it's no problem to physically send the proverbial officer handcuffed to a briefcase to the nuclear submarine before it submerges for 6 months. Also the messages to be secured are, um, short and... infrequent.

I kind of assumed the "customer" here would in fact be government agencies…

Re: The Futility of Lava Lamps: What Random Means

#60

Post by JKCalhoun »

p1necone wrote: post #17
JKCalhoun wrote: post #5

With a one-time pad being, as I understand it, the only really good encryption, I am surprised there is not a market for pairs of matched hard drives—the pair having the same "one time pad" stored on them (how you generate those numbers is left as an exercise for the company marketing them). A simple app could be used by parties on both ends of the message—an app that relies on an associated drive to act as the pad.…

Surely if you were that security conscious you'd never trust some third party to put the keys on the drives and not keep a copy for themselves - you'd just buy two regular drives and put the key on there yourself.

That's fine. I'm just not aware that even this is being done. But it seems to be pretty secure to being decrypted if captured in transit.
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