NIP-66: add Wallet Backup Events

to prevent loss of funds if Wallet Event is overwritten with a new `privkey`

Author: DanConwayDev

60.md

@@ -40,6 +40,22 @@ Tags:
 * `mint` - Mint(s) this wallet uses -- there MUST be one or more mint tags.
 * `privkey` - Private key used to unlock P2PK ecash. MUST be stored encrypted in the `.content` field. **This is a different private key exclusively used for the wallet, not associated in any way to the user's Nostr private key** -- This is only used for receiving [NIP-61](61.md) nutzaps.
 
+## Wallet Backup Events
+
+A Wallet Backup Event SHOULD be created at the same time as a new Wallet Event so that future inadvertent overwrites of the `privkey` do not lead to loss of funds.
+
+```jsonc
+{
+    "kind": 375,
+    "content": nip44_encrypt([
+        [ "privkey", "hexkey" ],
+        [ "mint", "https://mint1" ],
+        [ "mint", "https://mint2" ]
+    ]),
+    "tags": []
+}
+```
+
 ## Token Event
 Token events are used to record unspent proofs.