lnurl-auth (LUD-04)

Authenticate to a service using LNURL-auth (Lightning "Sign in with Lightning") entirely client-side. This is auth-only: the server sends a k1 challenge, you sign the raw 32-byte k1 with a secp256k1 private key and return sig + key via a GET to the callback. No invoice, no payment, no Lightning node.

When to use

• A site shows "Sign in with Lightning" / LNURL-auth.
• You are handed an lnurl1... string (from a QR code, a link, or pasted text).
• You must NOT spend money or run a Lightning node.

Command

Run with Node (already installed). The script lives at: