Quote from: leopard2 on March 10, 2014, 11:21:58 PM

I do not understand. Even the safest protocol cannot withstand a 51% attack. You could bring Securecoin down that way.

Quote from: amspir on March 10, 2014, 11:50:53 PM

The goal of any 51% attack is to control the protocol, for evil, for good, it doesn't matter. To change the protocol, you just need 51% control of the mining. You are hypothetically executing a 51% attack by getting 51% of the miner's power to follow the "BTC 2.0" protocol. If it can be done for "BTC 2.0", then it could be done by a government or criminal organization.

Basically we had this very situation last year.
A critical flaw in a just released new version of the standard client was discovered, which would have led to transactions being judged differently by miners, and thus to a split of the chain. It took the core devs just some hours to negotiate with some large miner pools to revert back. Before 12:00 PM UTC next day, most of the bitcoin network had followed this move, and the few problematic blocks where obsoleted this way.

Initially this created quite some turmoil and a lot of bad press, but in the end consensus was that this incident showed the Bitcoin Community's ability to deal with critical situations professionally.