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Date: Sun, 8 Jun 2014 17:35:34 -0400
From: Peter Todd <pete@petertodd.org>
To: Mike Hearn <mike@plan99.net>
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Cc: Bitcoin Dev <bitcoin-development@lists.sourceforge.net>
Subject: Re: [Bitcoin-development] Bloom bait
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On Sat, Jun 07, 2014 at 07:22:56PM +0800, Mike Hearn wrote:
> You can send different bloom filters to different peers too, so I'm not
> sure why you're listing subsetting as a unique advantage of prefix filter=
s.

As I explained in the email you're replying to and didn't quote, bloom
filters has O(n) cost per query, so sending different bloom filters to
different peers for privacy reasons costs the network significant disk
IO resources. If I were to actually implement it it'd look like a DoS
attack on the network.

Essentially with bloom filters you have to make a tradeoff between
scalability and privacy; with prefix filters you don't have to make that
ugly tradeoff. Notably that tradeoff gets worse if we ever increase the
Bitcoin blocksize.

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