Friday, April 25, 2014

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The bitcoin logo (Photo credit: Wikipedia)




There is no greater point of weakness in Bitcoin than a 51% attack. A fifty-one percent attack can shut down the network. This video discusses all the attack vectors available to an attacker. And there are many, even worse, the devastation available is catastrophic. While a 51% attack doesn't appear to offer a lot of financial gain, history is not just made up of rational actors.

James goes through Transaction Denial of Service, Selfish Mining, Monopoly Mining and Double Spending, finding fault with proposed patches and solutions. It is not pretty. As Gavin Andresen says, if someone was able to run a 51% attack "that would be bad". We agree. It would be very bad.

At the end of the video we discuss protocol changes that would make an attack much more difficult. We highlight Proof of Stake as a fallback algorithm. The biggest advantage is that POS provides a MUCH higher cost to the attacker for perpetrating such an attack. That, would be good.

In part one, we go through a cost analysis of the current hardware needed to launch a successful 51% attack to get a better picture how much it might cost. Unfortunately, the numbers are lower than expected, and most of the previously published values come in three to fifty times higher than actuality. In part two we will talk more about what an attacker might be able to do (double spending is not the worse tool at their disposal) and we prod at some possible solutions. Stay tuned


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