> You cannot pick and choose which parts of a block you like and which parts are "abusive".

In the current implementation, yes. But if you accept a proof, that a block is valid, instead of accepting a block in plaintext, then you can land on the same chain. Because after all, pruned nodes care only about the last 288 blocks, or something like that. If they can update their UTXO set, and always land on a valid chain, then they don't need transaction data in plaintext. They just need to update their UTXO database in a way, where attacking it would require breaking ECDSA, SHA-256, or similar things (a proof-based system, which would not weaken existing cryptographic assumptions, would be sufficient).

And the same is true about Initial Blockchain Download. Only today, you have to download hundreds of GBs, to synchronize the new node from scratch. But it can be changed, and as the size of the whole chain will grow, people will be pushed, to start deploying some optimizations. Otherwise, there will be even less nodes, if node operators will decide to trust centralized solutions instead, or do things, which already happened in some altcoins, where people passed around an already synced node data, and trusted, that it is valid (especially in CPU-mined coins, where verifying thousands blocks required similar effort, than mining a new block).

pt., 26 wrz 2025 o 02:25 Andrew Poelstra <apoelstra@wpsoftware.net> napisał(a):

On Thu, Sep 25, 2025 at 11:52:02AM -0600, Chris Guida wrote:
>
> Anyway, forcing users to relay transactions they consider abusive if they
> want to relay any transactions at all does not seem in keeping with
> bitcoin's ethos, not to mention that it obviously would never work.
>

Once a transaction is in a block, you need to relay the transaction if
you want to relay a block. You cannot pick and choose which parts of a
block you like and which parts are "abusive". This is what it means for
something to be a consensus system.

The purpose of the mempool is to approximate the contents of blocks,
both to help individual node operators (who would otherwise get large
quantities of "surprise transactions" with every block) and to help the
network (which would otherwise have poor propagation properties).

Any sort of filtering beyond that done by miners is contrary to this
purpose of the mempool. This is a technical fact. It has nothing to do
with "bitcoin's ethos", except its ethos as a consensus system, which
directly contradicts your point.

--
Andrew Poelstra
Director, Blockstream Research
Email: apoelstra at wpsoftware.net
Web: https://www.wpsoftware.net/andrew

The sun is always shining in space
-Justin Lewis-Webster

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