Subject: Re: [Bitcoin-development] BIP 34: Block v2, Height in Coinbase

From: Gregory Maxwell <[email-masked]>
Date: Fri, 6 Jul 2012 16:10:42 -0400

On Fri, Jul 6, 2012 at 4:02 PM, Gavin Andresen <[email-masked]> wrote:
>> But those issues are solvable through other, non-backwards incompatible
>> means. For example, mandate that a <transaction hash, output index> refers
>> to the first such pair that is not already spent. No?
>
> Yes, that is essentially what BIP 30 did.

It's important to note that bip 30 doesn't prevent duplication, it
just prevents the identified really evil outcome of the duplication.

There was discussion on doing the height _before_ that, but the
realization that the rewrites were a real vulnerability made it urgent
and rolling out the height will require time while the bip30 change
could be deployed more quickly.