While I mostly agree with you - it's easier said than done. How exactly are you going to buy $150 million (or whatever the needed amount is) of ASICs without be

While I mostly agree with you - it's easier said than done. How exactly are you going to buy $150 million (or whatever the needed amount is) of ASICs without being noticed? The government could obviously do it - but at least in the near future that sounds far fetched. Like wise as soon as your attack is noticed your IP addresses would be blocked by the other clients preventing you from adding to the chain. Edit: after looking more into the 51% attack IP blocking wont really solve it since it only would take a handful of unique IPs to pull off. Edit2: Couldn't we prevent the double spend part of the 51% attack (or at least make it more like 90%) by doing 2 things: 1) Merchants would only accept bit coins that have been in the block chain at least 6 blocks ago (this already is the recommended case) 2) Nodes reject any blocks received if they receive it over an hour (6 blocks worth) past receiving the 'sister' block in the competing (true) chain. This would prevent an attacker from 'reversing history.' What would be the drawbacks to this? Edit3: like wise we could stop the "prevent other people from making transactions" part of it (the only other part) by doing this: http://gavintech.blogspot.com/2012/05/neutralizing-51-attack.html http://gavintech.blogspot.com/2012/05/neutralizing-51-attack... I would love it if someone responded to this.