'Bitcoin is broken', researchers warn Typically, new Bitcoins are generated when groups of miners tackle complicated cryptographic puzzles. The first group to solve the puzzle is rewarded with Bitcoins, the news is circulated among the other miners, and everyone starts working on the next puzzle. However, so-called 'selfish' miners can obtain an unfair share of bitcoins by keeping the news that they have solved a puzzle to themselves, and quietly moving onto the next one, leaving the rest of the miners to continue working on a puzzle that has already been solved. "Once the system veers away from the happy mode where everyone is honest, there is no force that opposes the growth of really large pools that command control of the currency," the researchers said. While the attack is theoretical, the researchers claim that it could already be happening. They are calling for the Bitcoin community's help in deploying a software fix that would limit groups of miners to no more than 25 percent of the total number of nodes on the network, so that the Bitcoin ecosystem can be made more robust. The news comes at the value of Bitcoin has hit an all-time high of $267, surpassing the previous record of $266. The virtual currency dropped to $110 on October 3 after the FBI shut down Silk Road, and has now more than doubled its value in about a month. The total number of bitcoins in circulation is currently 11,955,775 and the market cap, using the current CoinDesk BPI now stands at $3.2bn - the highest it has ever been.