Eric Voskuil [ARCHIVE] on Nostr: 📅 Original date posted:2016-11-16 📝 Original message:On 11/16/2016 05:24 PM, ...

📅 Original date posted:2016-11-16
📝 Original message:On 11/16/2016 05:24 PM, Alex Morcos wrote:
> huh?
> can you give an example of how a duplicate transaction hash (in the same
> chain) can happen given BIP34?

"The pigeonhole principle arises in computer science. For example,
collisions are inevitable in a hash table because the number of possible
keys exceeds the number of indices in the array. A hashing algorithm, no
matter how clever, cannot avoid these collisions."

https://en.wikipedia.org/wiki/Pigeonhole_principle

e

> On Wed, Nov 16, 2016 at 7:00 PM, Eric Voskuil via bitcoin-dev wrote:
>
> On 11/16/2016 03:58 PM, Jorge Timón via bitcoin-dev wrote:
> > On Wed, Nov 16, 2016 at 3:18 PM, Thomas Kerin via bitcoin-dev
> > <bitcoin-dev at lists.linuxfoundation.org
> <mailto:bitcoin-dev at lists.linuxfoundation.org>> wrote:
> >> BIP30 actually was given similar treatment after a reasonable amount of time
> >> had passed.
> >> https://github.com/bitcoin/bitcoin/blob/master/src/main.cpp#L2392
> <https://github.com/bitcoin/bitcoin/blob/master/src/main.cpp#L2392>;
> >
> > This is not really the same. BIP30 is not validated after BIP34 is
> > active because blocks complying with BIP34 will always necessarily
> > comply with BIP30 (ie coinbases cannot be duplicated after they
> > include the block height).
>
> This is a misinterpretation of BIP30. Duplicate transaction hashes can
> and will happen and are perfectly valid in Bitcoin. BIP34 does not
> prevent this.
>
> e

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