From a9f3216102521d18655d2e41864e12f9321895e8 Mon Sep 17 00:00:00 2001
From: Kieran <kieran@harkin.me>
Date: Thu, 15 Jun 2023 15:51:07 +0100
Subject: [PATCH] nip-59 gift wrap construct

---
 packages/system/src/EventKind.ts      |  1 +
 packages/system/src/EventPublisher.ts | 29 ++++++++++++++++++++++++---
 2 files changed, 27 insertions(+), 3 deletions(-)

diff --git a/packages/system/src/EventKind.ts b/packages/system/src/EventKind.ts
index 512a1f0a..263de665 100644
--- a/packages/system/src/EventKind.ts
+++ b/packages/system/src/EventKind.ts
@@ -11,6 +11,7 @@ enum EventKind {
   BadgeAward = 8, // NIP-58
   SnortSubscriptions = 1000, // NIP-XX
   Polls = 6969, // NIP-69
+  GiftWrap = 1059, // NIP-59
   FileHeader = 1063, // NIP-94
   Relays = 10002, // NIP-65
   Ephemeral = 20_000,
diff --git a/packages/system/src/EventPublisher.ts b/packages/system/src/EventPublisher.ts
index 19d7475a..5d0d9fa8 100644
--- a/packages/system/src/EventPublisher.ts
+++ b/packages/system/src/EventPublisher.ts
@@ -1,12 +1,13 @@
 import * as secp from "@noble/curves/secp256k1";
 import * as utils from "@noble/curves/abstract/utils";
-import { unwrap, barrierQueue, processWorkQueue, WorkQueueItem } from "@snort/shared";
+import { unwrap, barrierQueue, processWorkQueue, WorkQueueItem, getPublicKey } from "@snort/shared";
 
 import {
   EventKind,
   FullRelaySettings,
   HexKey,
   Lists,
+  Nip44Encryptor,
   NostrEvent,
   RelaySettings,
   TaggedRawEvent,
@@ -16,6 +17,7 @@ import {
 
 import { EventBuilder } from "./EventBuilder";
 import { EventExt } from "./EventExt";
+import { findTag } from "./Utils";
 
 const Nip7Queue: Array<WorkQueueItem> = [];
 processWorkQueue(Nip7Queue);
@@ -58,9 +60,9 @@ export class EventPublisher {
    * Get a NIP-07 EventPublisher
    */
   static async nip7() {
-    if("nostr" in window) {
+    if ("nostr" in window) {
       const pubkey = await window.nostr?.getPublicKey();
-      if(pubkey) {
+      if (pubkey) {
         return new EventPublisher(pubkey);
       }
     }
@@ -309,4 +311,25 @@ export class EventPublisher {
     fnHook(eb);
     return await this.#sign(eb);
   }
+
+  /**
+   * NIP-59 Gift Wrap event with ephemeral key
+   */
+  async giftWrap(inner: NostrEvent) {
+    const secret = utils.bytesToHex(secp.secp256k1.utils.randomPrivateKey());
+
+    const pTag = findTag(inner, "p");
+    if (!pTag) throw new Error("Inner event must have a p tag");
+
+    const eb = new EventBuilder();
+    eb.pubKey(getPublicKey(secret));
+    eb.kind(EventKind.GiftWrap);
+    eb.tag(["p", pTag]);
+
+    const enc = new Nip44Encryptor();
+    const shared = enc.getSharedSecret(secret, pTag);
+    eb.content(enc.encryptData(JSON.stringify(inner), shared));
+
+    return await eb.buildAndSign(secret);
+  }
 }