MINING A CRYPTOCURRENCY can be an expensive business. Producing new coins, also known as tokens, can require computers to solve cryptographic puzzles, which takes large amounts of power. One way to keep costs down is to relocate mines to wherever electricity is cheapest. Cheaper still is having others foot the bill. An unsuspecting organisation’s power can be hijacked by stacking computers in a crawlspace or storage room, for example. Such operations, however, are regularly discovered, and culprits risk penalties and confiscated kit.