I've written up a more concrete proposal for this as a PR, I think it's a combination of multiple ideas from this thread:

GitHub

NUT-XX: Offline Spilman (unidirectional) channel by SatsAndSports · Pull Request #296 · cashubtc/nuts

Update: 2026-03-01 With this NUT, Alice and Bob can - using any mint supporting P2PK (NUT-11) - set up a channel where, once this 'cashu channe...

Thanks for this detailed explanation. The double spend section helped me to understand how sig-all and the re-used proof work. It's beautifully simple 😀

@vnprc I want my bitaxe to spend Spiel e-hash on internet access..

Maybe this can be made bi-directional. To do so, we need a way to make older transactions revocable, just like in Lightning. In Lightning, a transaction is revoked by revealing a preimage, such that the preimage allows the honest party to take all the balance (I might be slightly oversimplifying there) The mint has functionality to check which tokens have been spent *and with which secret*, and that might be the mechanism we can use to ensure that the honest party sees what the dishonest person has done and that the honest party has sufficient data needed to get their money back

I'm sorry what? Yo dawg...

Fabulous idea.

Is Spielman just a more German spelling of Spillman?