A currency surging in value at a breathtaking rate this week belongs to no nation and is issued by no central bank. It can be used to buy gold in California, a hamburger in Berlin or a house in Alberta. When desired, it can offer largely untraceable transactions.

The coin in question now has a global circulation worth more than $1.4 billion on paper. Yet almost no one, it seems, knows the true identity of its creator. In the United States, this mysterious money has become the darling of antigovernment libertarians and computer wizards prospecting in the virtual mines of cyberspace. In Europe, meanwhile, it has found its niche as the coinage of anarchic youth.