[Bitcoin-development] Draft BIP for Bloom filtering

Pieter Wuille pieter.wuille at gmail.com
Wed Oct 24 16:22:56 UTC 2012

On Wed, Oct 24, 2012 at 05:56:07PM +0200, Mike Hearn wrote:
> I've written a draft BIP describing the bloom filtering protocol
> extension developed by myself and Matt.
> https://en.bitcoin.it/wiki/BIP_0037
> Please read it and let me know if there are any missing details or
> things which sound wrong.

Some questions:
* why limit the number of matching transactions to 255?
* what does "each hash and key in the output script" mean exactly? what about the output script in its entirety?
* is sharing parts of the merkle branches not worth it?

> Design-wise, it occurred to me as I wrote the BIP that the method of
> delaying reception of invs is a bit ad-hoc. It may be better to have a
> bloom filter be sent in the version message itself. On the other hand,
> having a flag to delay invs means that the filter can be calculated in
> parallel to bringing up the network connections. Whilst actually
> making a Bloom filter is fast, with deterministic wallets you may need
> to do a lot of calculations to find the keys to scan for.

I'm not in favor of stuffing too much into the version message, it already seems overloaded.
A byte with some bit-flags is fine by me - higher bits can later be added for other boolean


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