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Date: Thu, 1 Mar 2012 10:15:01 +0000
Message-ID: <CAPBPUno7EaUeQHEb6jfR77k==p5_Q5Es8dGQiwmQW+DPSttDuA@mail.gmail.com>
From: Ben Reeves <support@pi.uk.com>
To: Bitcoin Dev <bitcoin-development@lists.sourceforge.net>
Content-Type: text/plain; charset=ISO-8859-1
Subject: Re: [Bitcoin-development] Duplicate transactions vulnerability
Precedence: list

Yes you are right. Any fix in DisconnectBlock() has the same potential issues.

I think the exchanges and major merchants need to be made aware that
they must also upgrade. Maybe bundle both BIP16 and BIP30 in 0.6 and
issue an advisory stating that this is a mandatory upgrade for
everyone.

It also might be prudent to have a blockchain repair script ready,
which checks the db for missing coinbase transactions and downloads
them from another peer or block explorer if necessary.

Thank You,
Ben Reeves
www.blockchain.info

On Wed, Feb 29, 2012 at 11:45 PM, Pieter Wuille <pieter.wuille@gmail.com> wrote:
> On Wed, Feb 29, 2012 at 11:00:42PM +0000, Ben Reeves wrote:
>> I'm not sure. What if they use a coinbase of a block that has already matured?
>
> Indeed; duplicate an old coinbase, fork chain without dupe, and spend the old coinbase.
> The 100-blocks maturity will not help against is.
>
> I'm not sure how you intend to fix DisconnectBlock() to prevent this in a backward-
> compatible way, though.
>
> --
> Pieter