On 23/04/2014 05:51 p.m., Mike Hearn wrote: > On Wed, Apr 23, 2014 at 10:44 PM, Adam Ritter > wrote: > > Isn't a faster blockchain for transactions (maybe as a sidechain) > solving the problem? If there would be a safe way for > 0-confirmation transactions, the Bitcoin blockchain wouldn't even > be needed. > > > The 10 minute average comes from a desire to balance wasted work due > to natural chain splits with latency. With a very fast block interval > you end up with lots of forks and things take longer to converge, > also, it can make attacks easier because an attacker is building on > his own blocks so he doesn't suffer propagation delays and the > attendant splits. > > It's not clear you can just make a faster block chain. 10 minutes is > somewhat arbitrary, it could be 5 minutes and the system would still > work, but it probably can't be 5 seconds. 5 seconds block interval is possible. I've simulate it with great success and I encourage anyone to repeat or check my simulations. There are a very few protocol modifications that are required to allow 5 seconds block, and most of them have already been discussed in the forums. For more information you can check my post: http://bitslog.wordpress.com/2014/02/17/5-sec-block-interval/ Also NimbleCoin is a new alt-coin that uses 5-sec block intervals, allows 100 tps and .... it's based on BitcoinJ (NimbleCoinJ now). So not only it is possible, but it was coded by Mike itself. Important note: the 5-sec block interval method probably requires a block reward forever. It doesn't work well if there is no block reward at all. > > Unfortunately for best physical-world usability you really need very > fast payments. A few seconds is competitive with modern credit cards. Another solution to achieve <5 secs block intervals is this: http://bitslog.wordpress.com/2014/03/20/mincen-a-new-protocol-to-achieve-instant-payments/ So the problem with 0-confirmations is solely of Bitcoin and other alt-coins, new alt-coins may achieve instant transactions and no not have to rely on 0-confirmations. Best regards, Sergio.