From: Eric Voskuil <eric@voskuil•org>
To: Tier Nolan <tier.nolan@gmail•com>,
Bitcoin Protocol Discussion
<bitcoin-dev@lists•linuxfoundation.org>
Subject: Re: [bitcoin-dev] BIP30 and BIP34 interaction (was Re: [BIP Proposal] Buried Deployments)
Date: Wed, 16 Nov 2016 16:43:08 -0800 [thread overview]
Message-ID: <e0e6679f-aec6-a579-667d-b5b58ea2360b@voskuil.org> (raw)
In-Reply-To: <CAE-z3OX5vak25UWcmBSe63OmoOVoGB394WmwyWwUcSxWeDOLhw@mail.gmail.com>
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> This means that all future transactions will have different txids...
rules do guarantee it.
No, it means that the chance is small, there is a difference.
If there is an address collision, someone may lose some money. If there
is a tx hash collision, and implementations handle this differently, it
will produce a chain split. As such this is not something that a node
can just dismiss. If they do they are implementing a hard fork.
e
On 11/16/2016 04:31 PM, Tier Nolan via bitcoin-dev wrote:
>
>
> On Thu, Nov 17, 2016 at 12:10 AM, Eric Voskuil via bitcoin-dev
> <bitcoin-dev@lists•linuxfoundation.org
> <mailto:bitcoin-dev@lists•linuxfoundation.org>> wrote:
>
> Both of these cases resulted from exact duplicate txs, which BIP34 now
> precludes. However nothing precludes different txs from having the same
> hash.
>
>
> The only way to have two transactions have the same txid is if their
> parents are identical, since the txids of the parents are included in a
> transaction.
>
> Coinbases have no parents, so it used to be possible for two of them to
> be identical.
>
> Duplicate outputs weren't possible in the database, so the later
> coinbase transaction effectively overwrote the earlier one.
>
> The happened for two coinbases. That is what the exceptions are for.
>
> Neither of the those coinbases were spent before the overwrite
> happened. I don't even think those coinbases were spent at all.
>
> This means that every activate coinbase transaction has a unique hash
> and all new coinbases will be unique.
>
> This means that all future transactions will have different txids.
>
> There might not be an explicit rule that says that txids have to be
> unique, but barring a break of the hash function, they rules do
> guarantee it.
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next prev parent reply other threads:[~2016-11-17 0:43 UTC|newest]
Thread overview: 19+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-11-17 0:06 Jorge Timón
2016-11-17 0:10 ` Eric Voskuil
2016-11-17 0:31 ` Tier Nolan
2016-11-17 0:43 ` Eric Voskuil [this message]
2016-11-17 0:53 ` Eric Voskuil
2016-11-17 8:44 ` Peter Todd
2016-11-17 9:58 ` Eric Voskuil
2016-11-17 10:22 ` Tier Nolan
2016-11-17 11:22 ` Eric Voskuil
2016-11-17 11:38 ` Alex Morcos
2016-11-17 12:22 ` Eric Voskuil
2016-11-17 15:40 ` Johnson Lau
2016-11-17 17:01 ` Eric Voskuil
2016-11-17 17:22 ` Johnson Lau
2016-11-17 17:49 ` Eric Voskuil
2016-11-17 18:08 ` Johnson Lau
2016-11-18 3:20 ` Eric Voskuil
2016-11-18 14:43 ` Johnson Lau
2016-11-18 16:47 ` Eric Voskuil
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