As part of the discussion around Blockstream’s awesome blockchain-from-space project, Blockstream Satellite, I managed to get into a public discussion about the merits of mining in space:

As well as the potentially harmful implications:

Unfortunately, I think people took that a little more seriously than it was intended, with one article1 even going as far as to describe the above as:

Peter Todd and Max Keiser consider Bitcoin mining in space wholly practical but not without its dangers.

Sorry guys, but the phrase “not as crazy as it sounds” just means we’re in the realm of hard sci-fi rather than pure fantasy: if space-based solar power ever becomes practical, then it’d made sense to put Bitcoin miners in space. But we still need to make space solar practical, and that’s a lot way off.

However, it’d made for some awesome hard sci-fi! Currently, even the always comprehensive Atomic Rocketships page on Future Money only mentions Bitcoin in passing. We should change this, and the best way to do so is by writing some good stories.

Speaking of, here’s one from a few years back that I sent2 to the bitcoin-dev mailing list in response to the selfish mining paper. I’m not about to claim it was actually any good, but it is an example of hard sci-fi. Specifically I was responding to the authors’ claims that selfish mining constituted a vulnerability so serious it needed to be fixed immediately even though the proposed fix appeared to itself have vulnerabilities3 (one of the authors even went as far as to claim Bitcoin was fundamentally broken4, and you should sell your BTC5).

Credit goes to Neil Fincham6 for editorial help.

RAND High Frequency Trading Corp

Here’s a perfectly plausible worst-case scenario, that could be happening right now: RAND High Frequency Trading Corp (a subsidiary of General Evil) has a low-latency network of fiber, line-of-sight microwave, and some experimental line-of-site neutrino links criss-crossing the globe. They can get data to and from any point on this planet faster than anyone else. Of course, in addition to their spectacular network they have an immense amount of computing power, as well as exotic overclocked liquid nitrogen bathed CPU’s that run at clockspeeds double what commercial hardware can do; in short, they have access to scalar performance no-one else has. Of course, they like to keep a healthy reserve so 99% of all this fancy gear is constantly idle. Whatever, they can afford it.

RAND just hired a bunch of fresh MIT graduates, the best of the best. Problem is the best of the best tends to make not so best mistakes, so RAND figures a Training Exercise is in order. Fortunately for them the NSA (a subsidiary of General Evil) slipped a rootkit into my keyboard a week or so ago - probably that time when I woke up in that farmers field with a splitting headache - and are reading what I’m typing right now.

I go on to explain how an excellent training exercise for these fresh MIT graduates would be to implement this nifty attack some Cornell researchers came up with. It’s really simple, elegant even, but to do it best what you really want is the kind of low-latency network a high-frequency-trading corporation would have. I then point out how a good training exercise ideally is done in a scenario where there is genuine risk and reward, but where the worst-case consequences are manageable - new hires to tend to screw up. (I then go on to explain my analog electronics background, and squeeze in some forced anecdote about how I blew up something worth a lot of money owned by my employers at some point in the distant past)

Unfortunately for the operators of BTC Guild, one of these new MIT grads happens to have a: passed General Evil’s psych screening with flying colors, and b: have spent too much time around the MIT Kidnappng Club. He decides it’d be easier to just kidnap the guy running BTC Guild than fill out the paperwork to borrow RAND’s FPGA cluster, so he does.

As expected the attack runs smoothly: with 30% of the hashing power, neutrino burst generator/encoders’s rigged around the globe to fire the moment another pool gets a block, and the odd DoS attack for fun, they quickly make a mockery of the Bitcoin network, reducing every other miners profitability to zero in minutes. The other miners don’t have a hope: their blocks have to travel the long way, along the surface of the earth, while RAND’s blocks shave off important milliseconds by taking the direct route. Of course, this doesn’t go unnoticed, er, eventually: 12 hours later the operators of GHash.IO, Eligius, slush, Bitminter, Eclipse and ASICMiner open their groggy eyes and mutter something about how that simulcast Tuesday party really shouldn’t have had an open bar… or so much coke.

They don’t even notice that the team from BTC Guild has vanished, but they do notice a YouTube video of Gavin right on doing his best Spock impression, er, I mean appealing for calm and promising that Top Men are working on the issue of empty blocks as we speak. Meanwhile CNN’s top headline reads “IS THIS THE END OF BITCOIN?!?!”

It takes another hour for the Aspirin’s to finally kick in, but eventually all get on IRC and start trying to resolve the issue - seems that whenever any of them produce a block, somehow by incredible coincidence someone else finds another block first. After a few rounds of this they’re getting suspicious. (if they weren’t all so hung-over they might have also found suspicious the fact that whenever they found a block they saw a sudden blue flash - Cherenkov radiation emitted when those neutrinos interacted with the vitreous humour in their eyeballs)

It’s quickly realized that “somehow” BTC Guild isn’t affected… GHash.IO and Eligius, 22% and 13% of the hashing power respectively, decide to try a little experiment: they peer to each other and only each other through an encrypted tunnel and… hey, no more lucky blocks! slush, 7% of the hashing power is invited to the peering group next, followed by Bitminter, 6%, and Eclipse, 2%, and finally ASICMiner, 1%, for a grand total of… 51% of the hashing power!

Of course, just creating blocks isn’t useful for users, they need to be distributed too, so someone quickly writes up a “one-way firewall” patch that allows the group’s blocks to propagate to the rest of the network. Blocks created by anyone else are ignored.

It takes a few more hours, but eventually the attacker seems to run out of blocks, and transaction processing returns to normal, albeit a little slow. (20 min block average) Of course, soon there’s a 3,000 post thread on bitcointalk complaining about the “centralized pool cartel”, but somehow life goes on.

The next day Gavin goes on CNN, and gives a lovely interview about how the past two days events show how the strength of the Bitcoin network is in the community. For balance they interview this annoying “Peter Todd” guy from “Keep Bitcoin Free!” who blathers on about how relying on altruism or something will doom the Bitcoin network in the long run. After the interview Gavin respectfully points out that maybe next time they find a so called “developer” with a ratio of bitcointalk posts to actual lines of code in the Bitcoin git repository better than one hundred to one. The producer just wishes that “Mike Hearn” guy was available; at least he’s got a sense of fashion, sheesh! Anyway, I’m out of space for my little story, but yeah, the ending involves a group of now-rich pool operators who decide to start a large financial services and data networking company, oh, and time-travel…


  1. I’ll spare the poor journalist the embarassment and let you find it yourself. But I will say having your late night post-bar tweets become news stories is an occupational hazard I didn’t expect to have five years ago!

  2. BIP proposal - patch to raise selfish mining threshold., Peter Todd, Nov 5th 2013, bitcoin-devevelopment mailing list

  3. Not sure where Gregory Maxwell actually published his response to the proposed fix, but I summarized it on the mailing list.

  4. no, it’s fundamentally broken at the protocol level., Emin Gün Sirer, Nov 3rd 2013, Twitter

  5. You heard it here first: now is a good time to sell your Bitcoins., Emin Gün Sirer, Nov 3rd 2013, Twitter

  6. The end of bitcoin is nigh! (Again), Neil Fincham, Nov 6th 2013