When Bitcoin broke into public consciousness in 2013, it couldn’t have been sexier: a digital currency being used to buy everything from drugs to cupcakes. Bitcoin's wild price ride — soaring up in late 2017 only to fall steadily back down this year — was also pretty exciting, even if the swings made its use as an everyday currency seem less plausible. Another aspect of Bitcoin that’s a bit less scintillating has generated almost as much enthusiasm: public online ledgers. Blockchain — the techno