Feature Request: Proof of Work Signed Extension

[JesseAbram]

The idea is to build a proof of work signed extension to optionally allow free txs on chain if a user client side PoW.

Flow

• User first creates a PoW proof using items in their transaction (nonce, address, so people can't reuse other's PoW)
• User submits this with their tx
• The proof of work difficulty scales with the usage of the chain

This is inspired by Hal Finney's usage of proof of work in emails as verifying proof of work is easy at the node level but trying to spam the chain with significant amounts of txs would become computationally intense

[apopiak]

@thiolliere The idea I mentioned Jesse had.

[kianenigma]

I would generally love to see a tutorial on how to turn the solochain template we currently have into a PoW chain. Raising this as something tip-worthy.

[burdges]

Afaik this has little to do with a PoW parachain per se.

Ain't clear why this should live inside blocks, like why should the chain ever care?

Instead, you could give collators some free tx space, which they fill however they like, but by default they accept some additional justification layer, outside the transaction envelop. You could provide a PoW example, but that's ridiculously insecure, especially browser WASM vs native, GPU, etc.

A a captcha would provide an far stronger defense. A captcha cannot go on-chain, because it's purely an interactive protocol between whatever captcha provider the RPC node trusts and the user agent. So captchas require an off-chain justification layer that simply trusts collators handle some blockspace well.