Halloween 2008 may have been a particularly frightening one, as the world economy was facing its most dangerous crisis since the Great Depression. Yet, it also happened to be the day that bitcoin, the most widely used cryptocurrency to date, was introduced in a rather simple and unassuming email to several hundred members of an obscure mailing list comprising cryptography experts and enthusiasts (it is worth noting that bitcoin as a digital currency should be distinguished from Bitcoin as a blockchain platform or protocol).

The sender, known only by the pseudonym “Satoshi Nakamoto,” wrote: “I’ve been working on a new electronic cash system that’s fully peer-to-peer, with no trusted third party,” followed by directions to the link http://www.bitcoin.org/bitcoin.pdf—a nine-page white paper about a peer-to-peer trustless system of digital “currency” that purports to solve the problem of double-spending.

After first becoming operational in January 2009, bitcoin and its progeny have exploded. Exactly seven years after Nakamoto sent his or her initial, enigmatic email, the October 31, 2015, cover of The Economist featured an article on blockchain (the technology underlying Bitcoin), dubbing it “the trust machine.”

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