LUD-21: LNURL-verify

21.md

@@ -0,0 +1,55 @@
+LUD-21: `verify` base spec.
+===============================
+
+`author: reneaaron`
+
+---
+
+Allow `SERVICE`s to check whether an invoice has been paid by contacting the `LN SERVICE`.
+
+A `SERVICE` can verify a payment was made without access to the user's node. Users can give their LNURL or [Lightning Address](https://lightningaddress.com) to a `SERVICE` and allow the `SERVICE` to create *and* verify invoices on their behalf. 
+
+This allows users to re-use existing wallets and `SERVICE`s to facilitate P2P payments without being an intermediary.
+
+## LNURL-verify
+
+An optional field `verify` is added to the `callback` response:
+
+```diff
+{
+  "status": "OK",
+  "routes": [],
+  "pr":     "lnbc10...",
+  "verify": "https://example.com/verify/894e7f7e...",
+}
+```
+
+The field `verify` provides an URL to a `SERVICE` to check if the invoice has been settled:
+
+`https://example.com/verify/894e7f7e...`
+
+Response
+```json
+{
+  "status": "OK",
+  "settled": true,
+  "preimage": "123456...",
+  "pr": "lnbc10..."
+}
+```
+
+```json
+{
+  "status": "OK",
+  "settled": false,
+  "preimage": null,
+  "pr": "lnbc10..."
+}
+```
+or
+```json
+{
+  "status": "ERROR",
+  "reason": "Not found"
+}
+```

README.md

@@ -25,6 +25,7 @@ These are all the individual documents describing each small piece of protocol t
 | [18][18] | Payer identity in `payRequest` protocol.                    | [Alby][alby], [BitBanana][bitbanana], [Blixt][blixt], [cliché][cliche], [OBW][obw], [ZBD Discord][zbd], [ZBD Telegram][zbd] |
 | [19][19] | Pay link discoverable from withdraw link.                   | [Blixt][blixt], [CoinCorner][coincorner], [OBW][obw], [LNbits][lnbits] |
 | [20][20] | Long payment description for pay protocol.                  | [Alby][alby], [BitBanana][bitbanana], [Blixt][blixt], [Clams][clams], [cliché][cliche], [Mash][mash], [OneKey][onekey], [Phoenix][phoenix] |
+| [21][21] | `verify` LNURL-pay payments                                 | [Alby][alby], [Mutiny][mutiny], [Stacker.News][stacker.news], [Zaprite][zaprite] |
 
 [alby]: https://github.com/getAlby/lightning-browser-extension
 [bipa]: https://bipa.app
@@ -49,6 +50,7 @@ These are all the individual documents describing each small piece of protocol t
 [ltb]: https://ln.tips
 [machankura]: https://8333.mobi
 [mash]: https://mash.com/consumer-experience/
+[mutiny]: https://www.mutinywallet.com
 [muun]: https://muun.com
 [OBW]: https://darthcoin.substack.com/p/obw-open-bitcoin-wallet
 [OneKey]: https://onekey.so
@@ -66,6 +68,7 @@ These are all the individual documents describing each small piece of protocol t
 [thunderhub]: https://www.thunderhub.io
 [wos]: https://www.walletofsatoshi.com
 [zap]: https://zaphq.io/
+[zaprite]: https://zaprite.com
 [zbd]: https://zebedee.io/wallet
 [zeus]: https://zeusln.app
 
@@ -216,6 +219,7 @@ Tools for developers
 [18]: 18.md
 [19]: 19.md
 [20]: 20.md
+[21]: 21.md
 
 Dependency Tree
 ---------------