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Show HN: Satoshi9000 analog BTC key generator (mechanical)

164 points| AJTSheppard | 1 year ago

I built this machine so I could generate Bitcoin keys that I could trust. Air-gapped and simple to use and understand (mechanical).

The Satoshi 9000 demo: https://youtu.be/bJiOia5PoGE

The key value proposition of the machine is that it generates analog randomness in the physical world and converts it into digital (1’s and 0’s) randomness. Seamlessly.

But it occurs to me that it may have other uses beyond crypto keys for your own use, such as: * Randomized clinical trials. Clinical trials need a high degree of transparency for ethical reasons; also, for legal reasons should it come to light after the trial has ended that patient selection and treatment selection was not random or in some way biased (say, by the researchers themselves). The machine described herein can provide that transparency to young and old patients, technical and non- technical. * Non-technical management. Many network engineers in need of security keys have bosses that are non-technical. Such managers might prefer security keys (and their generation) which are easier for them to understand. * Estate planning. Suppose members of a family were to inherit digital assets (such as Bitcoin, for example). Not all members of the family are technical and understand Bitcoin. However, each will still need to generate a secure Bitcoin key to receive their share of the inheritance. The machine described herein might help in that task because its source of randomness is more easily understood by laypeople and each can generate their own private key in private (in isolation with the machine). * Anywhere where the users have to have an intuitive understanding of how the randomness is being created; whether they are 5 years old, or 95 years old, and all ages in between.

I'm curious to know if any of the folks over at HN can think of other use cases?

89 comments

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rbanffy|1 year ago

Not sure I’d call it analog. Mechanical it is, but all the computation control is digital. A mechanical one would probably have a camshaft for storing the program and use gears to make measurements and computations.

Would probably need a large engine to power it as well, with careful control because the resisting force would vary along the machine cycles (this could be used as a side channel attack vector to figure out internal state from resisting force).

AJTSheppard|1 year ago

It's certainly the case that the coin/dice shaking is purely mechanical because before I built the control box, I operated the machine by simply connecting the motor to a bench power supply and applying the necessary voltage (which I would vary) for an amount of time (which I could vary) in a chosen rotational direction (which I could change). I could read the 1's and 0's just by looking at the coins and dice through the transparent dome.

The control box was a convenience and made the process fully programmable by the user. Which makes the machine far more flexible and useful.

I call it analog randomness because that's what I expect from the real world. For thousands of years, humans have used coins and dice to generate uncertain outcomes. And the fact that they typically generate only one of N outcomes (N=2 for coins, N=6 for common dice) is why humans use them. It is also why the Satoshi9000 uses them, and because its a kind of randomness that humans have an intuitive recognition of.

mattbee|1 year ago

This is pleasingly insane, congratulations! Is there a program to test the fairness of a given dice or coin? Is that a program that's even feasible to write?

vikingerik|1 year ago

You've always got the standard way to get fair random numbers from a fairness-unknown coin. Flip it twice. Restart if you get both heads or both tails. If you get H then T or T then H, those are equally probable, so take the first one of those as the final outcome.

This generalizes to a die of N sides. Roll it N times. If you don't get all N distinct results, restart. If you do, then take the first result as your final outcome.

(That may take a lot of trials for large N. It can be broken down by prime factorization, like roll 2-sided and 3-sided objects separately, and combine them for a d6 result.)

jdmoreira|1 year ago

You can measure the Shannon entropy of a sequence

TacticalCoder|1 year ago

Virtually everybody is using the BIP-39 / BIP-44 protocols to derive addresses from a 256 bit (or 128 bit) key.

If you have a way to generate 256 bit, you have a way to generate a Bitcoin (or Ethereum or whatever) wallet.

Some people trust their hardware wallet to generate a random 256 bit / 24 words (each word is 11 bit as the dictionary contains 2048 words: 24 words is 264 bits, 256 bit + 8 bit of checksum).

But others do it manually, in an analog way.

One way to do it to throw a 16-sided dice repeatedly: that's a good source of entropy. That's entirely analog.

BIP-39 has a checksum (4 bit for 128 bit keys and 8 bit for 256 bit keys), so you'll need some code to either find or verify the checksum. To do that people are typically going to use a fully offline/airgapped computer: for example an old desktop, without any Wifi capability, booted without any harddisk, from a Linux Live CD (I know, I know: you'll read their key from the electrical activity by tapping the electrical circuit outside their house or by firing a laser at their window, so it's not "fully airgapped": bla bla bla).

From that single 256 bit number you can derive wallets for all the coins you want.

Once people have generated their key by throwing dice, they'll typically store their key behind a HSM, on a hardware wallet. And the private key never leaves the hardware wallet (but can be used to sign transactions). And a "paper" copy of the key typically also lives in the analog world (and listen to Gandalf: "keep it safe", "keep it secure").

The video is definitely cool but creating a key in the real (non digital) world is something quite common.

AJTSheppard|1 year ago

Truth be told, that is exactly how I used to generate my crypto keys.

I would take 256 quarters (sometimes fewer and accept that some might be tossed more than once) and toss them to get ones and zeroes. Tedious, and somewhat error prone (see below). Then do the calculations by hand, also somewhat tedious and error prone.

There is plenty of research that demonstrates that humans are poor at tossing coins in an unbiased way. People cheat (especially if money hangs on the outcome) and people are also lazy, so that the first toss is vigorous and diligent, and so the coin tumbles end-over-end many times before coming to rest for a result (heads or tails), but after several hundred tosses, the vigor and diligence are gone and the coin barely leaves their hand.

Part of my motivation in building the Satoshi9000 was to automate this manual process and at the same time take out human bias. Which is to say, automate away the human part and automate the math of key generation. But at the same time, make it secure by having the machine air-gapped (that is, no connection to the outside world beyond a power cord) with the ability to walk-away with anything that might leave a clue as to how, why and when the machine was last used; what I refer to as "walk-away randomness" in the video. After removing the coins, SD cards (OS and user programs) and printout, what is left is little more than a motor and some wires. An adversary looking to recover your keys would have no clue as to whether the machine had ever been used, yet alone what for. Maybe it was simply used to generate a quick-pick for tomorrow's drawing of Powerball. You would have now way of knowing.

(As an aside, you could even walk away with the remaining paper roll from the printer, so an adversary would not even know how much had been printed! Also, the printer uses no ink and has no buffer/memory, which was a deliberate choice in the design.)

chungus|1 year ago

Love this. Is the private key printed on a separate piece of paper? I saw only #####'s. How long does it take to generate a full key using dice?

AJTSheppard|1 year ago

For the demo video I had the printer output the key-pair twice. Once with the private key in plain (visible) text, and another for the demo video with the private key replaced with ######'s.

I didn't think it wise for a public demo video to show everyone the private key!

Just like every aspect of the operation of the Satoshi9000, printer output is fully under the control of the user program. I simply put a "PAUSE(hit run to continue)" command between printing the key-pair properly, and printing the key-pair with the private key hashed out (the one visible in the demo video). The "PAUSE(hit run to continue)" appears in the "Log File/Debug" window while the program is paused.

The bit rate of the machine is around 4-bits per minute (time length of tossing/shaking is wholly under the control of the user - can be longer per shake), so for a 256 bit key it takes around an hour. But remember, Bitcoin keys are forever (or the remaining lifetime of the Universe, whichever is shorter), so taking an hour to generate it is short in comparison to its useful lifetime.

I hope that helps.

dools|1 year ago

Best use case I can think of is replacing the die roller in the board game trouble.

“You can pop a lot of trouble in the pop o matic bubble”

ape4|1 year ago

It would be nice to access it from /dev/random on a normal machine (at a very slow bitrate)

AJTSheppard|1 year ago

I like that idea. Someone also pointed out that it could be a live video feed online. Just take the bits (in pairs, left and right shakers, or singly, just left or right shaker, or some alternating choice of the two) you need in the way you want. As I say, I like the idea of making the random bit-stream available to users.

And, as you point out, given it generates randomness by tossing physical objects, it is naturally a low bit-rate machine.

theideaofcoffee|1 year ago

Love it. I wonder what the distribution of rolls/tosses for this looks like. This also reminds me of an automated dice roller thingy that someone built with a hopper of dice, a conveyor to bring the dice to the top of a ramp and ocr to record all of the rolls, a "Dice-o-matic" [0]. And a vidja of it in action [1].

[0] http://gamesbyemail.com/news/diceomatic

[1] https://www.youtube.com/watch?v=7n8LNxGbZbs

AJTSheppard|1 year ago

On an historical note, ever since dice and coins have been used by humans (thousands of years), there have been efforts to "automate" their tossing in an effort to make the toss or roll fair (unbiased). See, for example, the Vettweiss-Froitzheim Dice Tower, https://en.wikipedia.org/wiki/Vettweiss-Froitzheim_Dice_Towe...

The reason is simple. Humans are terrible sources of randomness. Especially true if money hangs on the outcome!

There are two principal components for bias of a coin or die toss/roll: 1) the coin or die itself (manufacturing defects, etc.), which if it exists is typically minuscule, and 2) the act of tossing or rolling by a human (a twist of the wrist, or a flick of the fingers), whose bias is enormous and which, as I say, is particularly pronounced if money hangs on the outcome.

The Satoshi9000 solves problem 2, the human element, by removing the human from the process altogether. Other than to press the "run" button.

abotsis|1 year ago

This concept reminds me of the cloudflare lava lamps! Awesome!

guenthert|1 year ago

I love the well executed combination of (electro-)mechanics and computing. Rare to see talent in both combined in one person. The printing of the result in the end is particularly charming.

Not sure, if there would ever be a mass market for such, but I can totally see it (or something similar) generating lotto numbers live on t.v. .

AJTSheppard|1 year ago

I would argue that the future belongs to people who can actually make useful things! If we revert to cave dwelling (which perhaps we might given the way things are going!), then being able to flake flint tools might be a far better skill to have than being a social media "influencer".

And today, most physical products require a combination of mechanical, electronic and programming skills. Fortunately, I have all three. I suggest people likewise diligently acquire all three.

It's also fun to build useful machines.

I worked in banking all over the globe for 30 years. I did not acquire my useful skills in that profession. Money yes. Useful skills no.

I acquired my mechanical/electronics/software skills long, long ago while a postgraduate in experimental physicist at Oxford, building space instrumentation. Why did I go into banking then, you ask? Poverty is the answer!

renewiltord|1 year ago

I found the video very entertaining. Very old-school. And boy, you’ve paid a lot of attention to the device. It looks very pro.

heisenzombie|1 year ago

A bingo cage or lottery machine could probably be made to do a similar task (just need a mechanism to return the balls to the machine after each drawing).

Anyway, quite charming!

whs|1 year ago

How does it read the value from the coins or dices?

imglorp|1 year ago

At 5:44, the vid shows a webcam facing up to photograph the bottom of the coin/die through the shaker window. I guess there's some CV to read the item.

stavros|1 year ago

This looks interesting, but there are much better (higher bitrate) sources of pure randomness, and I'm not sure what advantage this has over those. If I don't trust the machine that's generating the randomness, that doesn't only apply to the randomness component, I similarly mistrust this machine's code, the hardware, etc.

I'm not sure what this would add over, for example, entropy derived from a hash of the image of a camera's thermal noise profile.

pvg|1 year ago

I'm not sure what advantage this has over those.

Those usually don't look and sound like they were made by Doc Brown.

tylervigen|1 year ago

I think the advantage of this one is that it's funny. :)

AJTSheppard|1 year ago

The Satoshi9000 makes only one claim as a value proposition.

Value proposition: The key value proposition of the machine is that it generates analog randomness in the physical world and converts it into digital (1’s and 0’s) randomness. Especially noteworthy is that it can do so in a visibly, and to a lesser extent audibly (the sound of an agitated coin or die), way that is easily recognized and understood by humans. Other ways of generating digital randomness do not have this characteristic and in some ways have to be considered opaque to the public at large in their method of generating randomness. It comes down to whether people trust their eyes more than a black-box and whether people want this characteristic when generating randomness they are going to use.

I venture to say that anyone, from 5 years old and upwards who saw the machine in operation would understand how it is generating randomness. Dice from prehistory have been used by humans to generate random outcomes, and from the first millennium BC, when coins arose, the same can be said of coins.

Consider a randomized clinical trial. You may have patients that are not technically sophisticated, but must be convinced that the randomized aspects of the trial are done in a way they understand and are willing to give their consent. The same can be said for lawyers.

"I'm not sure what this would add over, for example, entropy derived from a hash of the image of a camera's thermal noise profile." Do you think a 95 year old grandmother will understand the principles by which this type of randomness is created?

Mistrust the machine? Then simply don't use it. ("Don't trust them lying eyes!") What I can say in its favor is it's connected to nothing (air-gapped), you fully control every important aspect of the randomness (fully programmable). Don't like the coins you have? Simply take a quarter from your own pocket and put it in the shaker. Don't like the microcontroller provided, buy (for $4) your own and plug it in. Ditto for the other components. All sensors, motor etc. are commodity parts; replace them. I think this machine is more provably back-door free than any cryptographic machine out there. As I point out in the video, all they important parts used in the generation of randomness walk-away in the palm of your hand -- what I call "walk-away randomness" in the video -- and all that's left is a motor and some wires.

As to the bitrate. Yes, it is not a high bitrate machine, the bit rate of the machine is around 4-bits per minute (time length of tossing/shaking and vigorousness of shaking is wholly under the control of the user - can be longer per shake, faster or slower, or variable during the shake), so for a 256 bit key it takes around an hour. But remember, Bitcoin keys are forever (or the remaining lifetime of the Universe, whichever is shorter), so taking an hour to generate it is short in comparison to its useful lifetime.

I hope the detail, and some background, helps.

qqqult|1 year ago

it's simple

raverbashing|1 year ago

So, to generate a random bitcoin key, that's how many coin tosses or die tosses?

darkstar999|1 year ago

The video says 128 cycles. Each cycle is 30 seconds, so it would take 64 minutes.

KaiserPro|1 year ago

This is cute, I like it

red_admiral|1 year ago

During the cold war, the Washington-Moscow "nuclear" hotline was set up with teleprinters and one-time pad keys for both directions. I imagine they had an analogue randomness key generator on both ends to generate the key material.

Presumably they're using ~Dual-EC DRBG~ some kind of quantum randomness generators these days.

robinduckett|1 year ago

Cymru am byth!

AJTSheppard|1 year ago

Yma o Hyd!

I started my working life at age sixteen as a coal miner at the Deep Navigation Colliery in South Wales.

Today, building useful and interesting machines has a lot in common with coal mining. A lot of hard work, and the perpetual risk of being crushed to death by 1,000 feet of rock above you. (The last part is perhaps a bit of a stretch, but it oftentimes feels that way!)

keeganpoppen|1 year ago

i love everything about this, including the absurd impracticality. which i, personally, would call "art".

hggh|1 year ago

Why the thermal printer? The text fades eventually and you will lose your private keys.

AJTSheppard|1 year ago

Correct. But it does allow you to walk-away (with other stuff from the machine) with the keys immediately after generating them, leaving a machine which is little more than a motor and some wires at that point.

So what I typically do is print a warning at the top and bottom of the printout urging the user to transcribe the important parts using archival paper and pen as soon as they can.

Also, if you look at the video, you will see an "Archival Printer" port on the front of the control box because I’m developing a printer that prints the keys (plus QR codes) on metal so they last for decades and perhaps centuries. That may be useful in estate planning where the key may be locked away in a safe, or a lawyers safe, for generations. But transcribing to archival paper and pen is relatively permanent (decades) and is easy and seems to work well (lawyers like it).

willvarfar|1 year ago

Yes it really ought punch brail or something?

jszymborski|1 year ago

There is another slot below that reads "archival grade printer".

rtkwe|1 year ago

I think the cloudflare video wall is a more practical way to mass generate entropy but this is suitably madcap I enjoy it. There are also other existing methods but they're not as... clearly demonstrable... as this like is used in existing hardware TRNGs.

https://en.wikipedia.org/wiki/Hardware_random_number_generat...

AJTSheppard|1 year ago

The case I would make for the Satoshi9000 is that its method of generating randomness is intuitively understood by anyone from five years old to ninety-five years old, technical or non-technical.

I think it would be a stretch to think you could pull a random person off the street, point to a wall of lava lamps, and ask "do you see the randomness, how does it work?" Whereas, I think if you pull a random person off the street, let them watch the Satoshi9000 do its thing, and ask "do you see the randomness, how does it work?" you might get an answer that makes sense.

That, in a nutshell, is the value proposition behind the Satoshi9000.

duskwuff|1 year ago

The Cloudflare lava lamp wall isn't actually that practical. You get more randomness with the lens caps on the cameras (i.e. where the whole frame is just thermal noise).

nodlek|1 year ago

People are missing the point that it is creative and gets the job done, conversation pieces can go a long way.

AJTSheppard|1 year ago

This comment brought a smile to my face.

When I showed the machine to my son, Nate, a mechanical engineer, he thought it looked like something from a 1950's sci-fi movie like "Forbidden Planet". Back then, plastics were high-tech and new, and with the acrylic domes, the Satoshi9000 would not look out of place on the set of that movie.

He suggested that every coffee table should have one!

fkyoureadthedoc|1 year ago

Am I missing something? There's not a single negative comment in the post as of now.

londons_explore|1 year ago

I am super dubious of mechanical systems for randomness... Newtons laws are fully predictable after all...

I suggest that any system like this has the output XOR'ed with another random source. If two random sources are XOR'ed together, then both need to be predictable for the output to be predictable.

keeganpoppen|1 year ago

i think you should check your work with this comment a bit... (ok more than a bit)

what is the point in having a source of randomness if you need to XOR with a random source? relatedly, if you have a source of randomness, (1) please share and (2) well, there's no real need to go down this particular rabbit hole at all, well, is there?

independent of all of that, you seem to be anthropomorphizing the XOR function a bit... sure, there are some contexts where "1"s "mean" something and "0"s don't (sparse coding? and yeah, that is some pretty generous contortion, but hey: we're all friends here, right?), but in the case of "randomness"* the whole point (presumably) is that predicting "1"s and predicting "0"s are both exactly the same thing: Sisyphean.

i'm not sure that the word "random" "means" any thing beyond "distribution that we cannot model". which is a fine definition, given that models are how we attack random number generation...

* mind you i challenge the reader to pray tell what "randomness" even really means in anything other than a pseudorandom context (aka used to justify the randomness of various algorithms). isn't it oddly instructive that we use something that would pass as a proxy for "random"ness as the basis for our official definition for the second? (Cesium-133). the "second" is no more real than it is random. random is defined via a threshold of non-randomness, and all that we value as discrete and integral in the world that exists beyond our minds (-- if it does, in fact, even exist (or even "exist")--) is a house built upon sand. well, worse than that: the universe "works" because Avogadro's Number is a hell of a lot closer to infinity than it is to zero, and that's good enough for me. log(N) < 100.

freeplay|1 year ago

Side note: excellent unintentional ASMR once Andrew starts explaining how the machine works.