Re: [bitcoin-dev] Committed bloom filters for improved wallet performance and SPV security

[Leo Wandersleb <leo@LeoWandersleb.de>]

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On 01/04/2017 12:06 AM, adiabat via bitcoin-dev wrote:
> Also, if you're running a light client, and storing the filters the way you
> store block headers, there's really no reason to go all the way back to height
> 0.  You can start grabbing headers at some point a while ago, before your set
> of keys was generated.  I think it'd be very worth it even with GB-scale disk
> usage.

The really great benefit of having this index is that you could implement rather
efficient cold wallet spending once the wallet has the full index.

With Mycelium you can currently spend funds from a paper wallet or a BIP39
sentence but at the cost of sharing all addresses with our servers. Schildbach
would share addresses with random full nodes for hours or days to find funds of
a new private key with unknown creation date. With CBF it would still be a
matter of maybe minutes on a phone to identify relevant blocks and download
these but it would be very feasible to implement a private, cold storage
spending feature.

Also the index could be further partitioned by P2PKH, P2PK, P2SH, … This would
lead to a very minor privacy leak for a reasonable reduction in index size.

-- 

Leo Wandersleb



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