calle 👁️⚡👁️ on Nostr: Ok I've built this for fun and it's incredible. A Cashu gateway: it's a normal Cashu ...

Ok I've built this for fun and it's incredible.

A Cashu gateway: it's a normal Cashu user who has a Lightning node (or another Lightning payment backend). Everyone can act like a gateway as long as the mint supports ecash HTLCs (NUT-15).

If you as a Cashu user know of such a gateway, your wallet can send your Lightning payment request to it instead of to the mint.

The gateway responds with an amount (it can take a fee). If you agree, you send it ecash, and it pays your Lightning invoice. The process is atomic.

What does that mean? Let's think a little ahead and imagine this was deployed on a significant scale.

Even if the mint is full KYC for peg-in and peg-outs, a user could still make Lightning payments anonymously with the help of other users.

(!!! this alone would be huge !!!)

This would also enable us to make on-chain-only mints which opens up a whole new way of building mints (reserves could be in a multisig for example).

Crazy part: Gateways can be lazy and use custodial Lightning backends. The user doesn't care as long as the invoice gets paid.

Yes. That means you could use your Strike or Blink or LNbits account to act as a Gateway for a Cashu mint you like.

There could be many of crazy people like you. Nobody would ever know. Neither the mint. nor your LN service provider would notice. They all just see invoices.

It gets weirder. Gateways could use *another Cashu mint* as an LN backend. I know sounds like an inception nut but bare with me.

A user of mint M1 can ask a gateway of mint M1 to pay an invoice. The gateway could pay the invoice via mint M2 and receive ecash from M1 in return.

I always thought "you could run a mint for a thousand users on a Strike or a Blink backend without them even noticing the smallest thing".

Now I think you could probably run a mint for 100k users without them noticing, if there are other gateways handling payments for everyone.

Note: this is still experimental. Only paying works right now over the gateway, not receiving (more complicated).

The bast part though is that it doesn't require any Cashu protocol changes and the mints don't have to give you permission to do this.

It's all pretty nuts.

quoting
note142q…d5kr

Weekend project: Cashu Lightning gateway.

Needed: Cashu wallet for gateway, Lightning

Steps:
- user to gateway: yo! would you pay this LN invoice for me?
- gateway: sure, gibbs HTLC ecash
- checks if HTLC has same hash as LN invoice
- if so, pays LN
- everybody happy