Re: [bitcoin-dev] UTXO growth scaling solution proposal

From: Mark Friedenbach <mark@friedenbach•org>
To: Thomas Guyot-Sionnest <dermoth@aei•ca>,
	Bitcoin Protocol Discussion
	<bitcoin-dev@lists•linuxfoundation.org>
Cc: Rodney Morris <rodney.morris@gmail•com>
Subject: Re: [bitcoin-dev] UTXO growth scaling solution proposal
Date: Tue, 22 Aug 2017 20:26:19 -0700	[thread overview]
Message-ID: <02ECA1E2-B113-4668-984A-70445052C8B9@friedenbach.org> (raw)
In-Reply-To: <f440fb62-4837-b98d-15e5-fd871ce3869e@aei.ca>

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Lock time transactions have been valid for over a year now I believe. In any case we can't scan the block chain for usage patterns in UTXOs because P2SH puts the script in the signature on spend.

> On Aug 22, 2017, at 4:29 PM, Thomas Guyot-Sionnest via bitcoin-dev <bitcoin-dev@lists•linuxfoundation.org> wrote:
> 
> I'm just getting the proposal out... if we decide to go forward (pretty huge "if" right now) whenever it kicks in after 15, 50 or 100 years should be decided as early as possible.
> 
> Are CheckLockTimeVerify transactions accepted yet? I thought most special transactions were only accepted on Testnet... In any case we should be able to scan the blockchain and look for any such transaction. And I hate to make this more complex, but maybe re-issuing the tx from coinbase could be an option?
> 
> --
> Thomas
> 
>> On 22/08/17 06:58 PM, Rodney Morris via bitcoin-dev wrote:
>> Thomas et.al.
>> 
>> So, in your minds, anyone who locked up coins using CLTV for their child to receive on their 21st birthday, for the sake of argument, has effectively forfeit those coins after the fact?  You are going to force anyone who took coins offline (cryptosteel, paper, doesn't matter) to bring those coins back online, with the inherent security risks?
>> 
>> In my mind, the only sane way to even begin discussing an approach implementing such a thing - where coins "expire" after X years - would be to give the entire ecosystem X*N years warning, where N > 1.5.  I'd also suggest X would need to be closer to the life span of a human than zero.  Mind you, I'd suggest this "feature" would need to be coded and deployed as a future-hard-fork X*N years ahead of time.  A-la Satoshi's blog post regarding increasing block size limit, a good enough approximation would be to add a block height check to the code that approximates X*N years, based on 10 minute blocks.  The transparency around such a change would need to be radical and absolute.
>> 
>> I'd also suggest that, similar to CLTV, it only makes sense to discuss creating a "never expire" transaction output, if such a feature were being seriously considered.
>> 
>> If you think discussions around a block size increase were difficult, then we'll need a new word to describe the challenges and vitriol that would arise in arguments that will follow this discussion should it be seriously proposed, IMHO.
>> 
>> I also don't think it's reasonable to conflate the discussion herein with discussion about what to do when ECC or SHA256 is broken.  The weakening/breaking of ECC poses a real risk to the stability of Bitcoin - the possible release of Satoshi's stash being the most obvious example - and what to do about that will require serious consideration when the time comes.  Even if the end result is the same - that coins older than "X" will be invalidated - everything else important about the scenarios are different as far as I can see.
>> 
>> Rodney
>> 
> 
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