Our paper describes a way to create vaults, special accounts whose keys can be neutralized if they fall into the hands of attackers. Vaults are Bitcoin’s decentralized version of you calling your bank to report a stolen credit card -- it renders the attacker’s transactions null and void. And here’s the interesting part: in so doing, vaults demotivate key theft in the first place. An attacker who knows that he will not be able to get away with theft is less likely to attack in the first place, compared to current Bitcoin attackers who are guaranteed that their hacking efforts will be handsomely rewarded.

Operationally, the idea is simple. You send your money to a vault address that you yourself create. Every vault address has a vault key and a recovery key. When spending money from the vault address with the corresponding vault key, you must wait for a predefined amount of time (called the unvaulting period) that you established at the time you created the vault -- say, 24 hours. When all goes well, your vault funds are unlocked after the unvaulting period and you can move them to a standard address and subsequently spend them in the usual way. Now, in case Harry the Hacker gets a hold of your vault key, you have 24 hours to revert any transaction issued by Harry, using the recovery key. His theft, essentially, gets undone, and the funds are diverted unilaterally to their rightful owner. It’s like an “undo” facility that the modern banking world relies on, but for Bitcoin.