Subject: Re: [bitcoindev] UTXO checkpoint transactions

From: Eric Voskuil <[email-masked]>
Date: Tue, 28 Jan 2025 01:42:31 -0500

Hi Erik,

Miners committing to a checkpoint does not make the checkpoint valid. The only way one would know it’s valid is by validating the chain up to that point.

Given that it implies one would be trusting hash power for validity there is no need for a utxo set. SPV is sufficient. A utxo set is only necessary for validation.

e

On Jan 28, 2025, at 01:32, Erik Aronesty <[email-masked]> wrote:

Has it been considered to add a UTXO checkpoint transaction

Here's how it would work

Someone submits a transaction that contains a large fee and a hash of the UTXO set along with block height as opcode parameter

Miners refuse to include this transaction unless the hash of the UTXO set matches

Because performing that hash is expensive, it should have an extremely high cost factor, equivalent to say a 100KB transaction or something

These checkpoints are explicitly for the purpose of fast-synchronizing extremely lightweight nodes.  It's reasonable to refuse to use a checkpoint that isn't at least several months old.   It should be easy for anyone to find a sufficiently aged checkpoint and synchronize from that point onward.

Or is this just a solution without a problem?

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