When kidnappers ask for a ransom, they’d be wise to have a plan to store the loot securely. Cybercriminals aren’t exempt.

Hackers who broke into and encrypted the computer files of the US’s Colonial Pipeline operator last month made a now-common demand: pay me, or your files stay locked forever. The ransom was to be paid in bitcoin.

Cryptocurrencies, according to folklore (and law enforcement), are a favoured medium of crooks and terrorists because they’re purely digital and hard to trace. Computer ransom attacks happened before bitcoin was invented, but have surged since such tokens became popular...