“Closing down the Silk Road and arresting its alleged operator has left the FBI in uncharted territory. After shuttering the hidden site, law enforcement went to work confiscating the money and materials belonging to supposed drug kingpin Ross Ulbricht, but this usually routine procedure is proving especially troublesome in this case. The cache of more than 600,000 bitcoins in Ulbricht’s personal fortune are still inaccessible to the FBI. The only way to move Bitcoins out of a private wallet is to have the corresponding private key to authorize the transaction. The FBI has been unable to get through the encryption protecting Ulbricht’s wallet, leaving all those Bitcoins — amounting to roughly $80 million at current rates — out of reach. Based on publicly available data, this is about 5% of all Bitcoins in existence right now.