In their nearly four weeks of running Hansa, the Dutch had surveilled twenty-seven thousand transactions. After shutting down the site, they seized 1,200 bitcoins from Hansa, worth tens of millions of dollars as of this writing, thanks in part to silently sabotaging the site’s implementation of a Bitcoin feature called multi-signature transactions, designed to make that sort of simple confiscation impossible. They had collected at least some amount of data on a staggering total of 420,000 users, including more than 10,000 home addresses.
