[Bitcoin-development] Coinbase reallocation to discourage Finney attacks

Sergio Lerner sergiolerner at certimix.com
Thu Apr 24 15:13:40 UTC 2014

On 23/04/2014 05:51 p.m., Mike Hearn wrote:
> On Wed, Apr 23, 2014 at 10:44 PM, Adam Ritter <aritter at gmail.com
> <mailto:aritter at gmail.com>> 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:
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:

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,

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