Episode #195 – The Gap

Bitcoin is a machine for remembering, and it works because of one deliberate hole in its memory. The Coldcard entropy failure filled that hole with facts the world had already written down somewhere, which turned a private key into an explainable object and cost people hundreds of millions of dollars without a single server being breached. Entropy is the size of the gap in the record, and the episode works out why nothing else in the system can do its job.

Episode Summary

Bitcoin is a machine for remembering. Every block, every transaction, every satoshi that has ever moved is written down in public, the writing is permanent, and it is checkable by anybody with a laptop and a small amount of compute. Fifty years from now a payment made in 2011 from some random bedroom in Helsinki will still be auditable, which is the whole of the invention, with one deliberate exception. There is a single fact recorded nowhere: not in any block, not on any node, not in any of the government databases tracking the network. That fact is the private key, and it has to be that way, because a system that remembered absolutely everything would also give everything away. Anything fully written down is something somebody can work out. Bitcoin therefore needs exactly one hole in its memory, and that tiny hole is the only thing standing between a person’s coins and every other person on the planet. Entropy, throughout this episode, means the size of that hole and nothing more elaborate. What happened at Coldcard was not a breach in any conventional sense. No servers were compromised, no houses were entered, nobody was manipulated into handing over their words, and nobody was attacked with a wrench. The people who lost money had by any normal standard done almost everything right: they bought a well-supported hardware wallet, generated a seed on it, wrote the words down, and put them somewhere safe, some of them doing exactly that correctly for five years. The failure sat underneath all of it. The firmware defined the flag for the hardware random number generator as zero, meaning off, and the library that needed to know whether the hardware generator was available asked whether the setting existed rather than whether it was switched on. Zero exists. The check passed, on every device and every time, for five years, and seed generation fell back quietly to a deterministic software algorithm, a thing that produces numbers which look random and are in fact worked out completely in adva