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To: Jeff Garzik <jgarzik@gmail.com>, Peter Todd <pete@petertodd.org>
From: s7r <s7r@sky-ip.org>
Message-ID: <56769453.4060903@sky-ip.org>
Date: Sun, 20 Dec 2015 13:43:15 +0200
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Cc: Bitcoin Dev <bitcoin-dev@lists.linuxfoundation.org>
Subject: Re: [bitcoin-dev] Forget dormant UTXOs without confiscating bitcoin
Precedence: list

What will be the actual effect over wallets?

Say I have the private key for a dormant UTXO older than the
consensus-critical maximum UTXO age. The UTXO is not part of the cache.
So I setup a full node and import my old private key (wallet.dat). Will
I even see the correct balance (where will it get if from, since it's
dropped from the cache), or it will show me a 0 balance?

If I can see the correct balance, where can I get the proof I need and
what ensures I'll always be able to get that proof?

On 12/20/2015 1:34 PM, Jeff Garzik via bitcoin-dev wrote:
> On Sun, Dec 20, 2015 at 6:24 AM, Peter Todd via bitcoin-dev
> <bitcoin-dev@lists.linuxfoundation.org
> <mailto:bitcoin-dev@lists.linuxfoundation.org>> wrote:
> 
>     What I proprosed is that a consensus-critical maximum UTXO age be part
>     of the protocol; UTXO's younger than that age are expected to be cached.
>     For UTXO's older than that age, they can be dropped from the cache,
>     however to spend them you are required to provide the proof, and that
>     proof counts as blockchain space to account for the fact that they do
>     need to be broadcast on the network.
> 
> 
> Yes, this is almost what -has- to happen in the long term.
> 
> Ideally we should start having wallets generate those proofs now, and
> then introduce the max-age as a second step as a planned hard fork a
> couple years down the line.
> 
> However,
> 1) There is also the open question of "grandfathered" UTXOs - for those
> wallets generated in 2009, buried in a landfill and then dug out 10
> years ago
> 
> 2) This reverses the useful minimization attribute of HD wallets - "just
> backup the seed"
> 
>