LUD-25 turns an ordinary LNURL-withdraw k1 into a bearer note secured
by real Bitcoin script — a hashlock, a signature, a timelock, or any spending
condition you can write. Copy it, print it, tap it over NFC, hand it to whoever's
next to you. No new endpoint. No new encoding. Just
LUD-03
and LUD-06,
made programmable.
SPENDING CONDITIONS
A plain withdraw link pays whoever holds the string. LUD-25 keeps that link exactly as it is — but lets the issuer decide, in Bitcoin script, what "holding" has to mean.
A note is still a plain withdrawRequest k1. A wallet that's never heard of LNURLcash redeems it exactly like any LUD-03 link.
Hashlock, signature, timelock, or a multi-party leaf — one verification rule covers them all, delegated straight to Bitcoin's own script interpreter.
Notes carry their own certificate. Two wallets can trade one hand-to-hand with no signal, and settle with the mint whenever they're back online.
THE LNURLCASH STACK
Three independent, spec-compliant implementations of LUD-25. Run one, or all three — every note is redeemable across all of them, and by any LNURL-withdraw wallet that has never heard of LNURLcash.
Pay a Lightning address. Get a banknote.
A minimal backend implementing LUD-25 on plain LUD-03 withdrawRequest
and LUD-06 payRequest. Paying its Lightning address mints a note —
the payment preimage becomes the k1 that holds its value.
No backend. No accounts. Just your browser.
A single static page that holds notes encrypted in local storage and talks straight to whichever mint issued them. Works against any LUD-25-compliant service, not only Mint.
Cold storage for a bearer note.
An ESP32-S3 hardware wallet built for LNURLcash. Note secrets come from a hardware RNG and never leave the device until a physical button says so.
Plus libraries in TypeScript, Python, Rust, Kotlin & Go, tracked on awesome-lnurlcash ↗