"Even the purest technology has to live in an impure world. Both the code and the idea of bitcoin may have been impregnable, but bitcoins themselves—unique strings of numbers that constitute units of the currency—are discrete pieces of information that have to be stored somewhere. By default, bitcoin kept users’ currency in a digital 'wallet' on their desktop, and when bitcoins were worth very little, easy to mine, and possessed only by techies, that was sufficient. But once they started to become valuable, a PC felt inadequate. Some users protected their bitcoins by creating multiple backups, encrypting and storing them on thumb drives, on forensically scrubbed virgin computers without Internet connections, in the cloud, and on printouts stored in safe-deposit boxes. But even some sophisticated early adopters had trouble keeping their bitcoins safe. Stefan Thomas had three copies of his wallet yet inadvertently managed to erase two of them and lose his password for the third. In a stroke, he lost about 7,000 bitcoins, at the time worth about $140,000. 'I spent a week trying to recover it', he says. 'It was pretty painful'. Most people who have cash to protect put it in a bank, an institution about which the more zealous bitcoiners were deeply leery. Instead, for this new currency, a primitive and unregulated financial-services industry began to develop. Fly-by-night online 'wallet services' promised to safeguard clients’ digital assets. Exchanges allowed anyone to trade bitcoins for dollars or other currencies. Bitcoin itself might have been decentralized, but users were now blindly entrusting increasing amounts of currency to third parties that even the most radical libertarian would be hard-pressed to claim were more secure than federally insured institutions. Most were Internet storefronts, run by who knows who from who knows where.
Sure enough, as the price headed upward, disturbing events began to bedevil the bitcoiners. In mid-June, someone calling himself Allinvain reported that 25,000 bitcoins worth more than $500,000 had been stolen from his computer. (To this day, nobody knows whether this claim is true.) About a week later, a hacker pulled off an ingenious attack on a Tokyo-based exchange site called Mt. Gox, which handled 90 percent of all bitcoin exchange transactions. Mt. Gox restricted account withdrawals to $1,000 worth of bitcoins per day (at the time of the attack, roughly 35 bitcoins). After he broke into Mt. Gox’s system, the hacker simulated a massive sell-off, driving the exchange rate to zero and letting him withdraw potentially tens of thousands of other people’s bitcoins.
As it happened, market forces conspired to thwart the scheme. The price plummeted, but as speculators flocked to take advantage of the fire sale, they quickly drove it back up, limiting the thief’s haul to only around 2,000 bitcoins. The exchange ceased operations for a week and rolled back the postcrash transactions, but the damage had been done; the bitcoin never got back above $17."
Den ganzen Artikel findet man hier: http://www.wired.com/magazine/2011/11/mf_bitcoin/all/1