add nip59 (#438)

* feat(nip59) add nip59 based on https://nips.nostr.com/59

* fix(nip59) export the code as nip59

* Update nip59.ts

Co-authored-by: Asai Toshiya <to.asai.60@gmail.com>

* fix(nip59) change GiftWrap kind and using kinds from kinds.ts

---------

Co-authored-by: Asai Toshiya <to.asai.60@gmail.com>

nip59.ts

@@ -0,0 +1,76 @@
+
+import { EventTemplate, UnsignedEvent, Event } from './core.ts'
+import { getConversationKey, decrypt, encrypt } from './nip44.ts'
+import { getEventHash, generateSecretKey, finalizeEvent, getPublicKey } from './pure.ts'
+import { Seal, GiftWrap } from './kinds.ts'
+
+type Rumor = UnsignedEvent & { id: string }
+
+const TWO_DAYS = 2 * 24 * 60 * 60
+
+const now = () => Math.round(Date.now() / 1000)
+const randomNow = () => Math.round(now() - (Math.random() * TWO_DAYS))
+
+
+const nip44ConversationKey = (privateKey: Uint8Array, publicKey: string) =>
+  getConversationKey(privateKey, publicKey)
+
+const nip44Encrypt = (data: EventTemplate, privateKey: Uint8Array, publicKey: string) =>
+  encrypt(JSON.stringify(data), nip44ConversationKey(privateKey, publicKey))
+
+const nip44Decrypt = (data: Event, privateKey: Uint8Array) =>
+  JSON.parse(decrypt(data.content, nip44ConversationKey(privateKey, data.pubkey)))
+
+export function createRumor(event: Partial<UnsignedEvent>, privateKey: Uint8Array) {
+  const rumor = {
+    created_at: now(),
+    content: "",
+    tags: [],
+    ...event,
+    pubkey: getPublicKey(privateKey),
+  } as any
+
+  rumor.id = getEventHash(rumor)
+
+  return rumor as Rumor
+}
+
+export function createSeal(rumor: Rumor, privateKey: Uint8Array, recipientPublicKey: string) {
+  return finalizeEvent(
+    {
+      kind: Seal,
+      content: nip44Encrypt(rumor, privateKey, recipientPublicKey),
+      created_at: randomNow(),
+      tags: [],
+    },
+    privateKey
+  ) as Event
+}
+
+export function createWrap(seal: Event, recipientPublicKey: string) {
+  const randomKey = generateSecretKey()
+
+  return finalizeEvent(
+    {
+      kind: GiftWrap,
+      content: nip44Encrypt(seal, randomKey, recipientPublicKey),
+      created_at: randomNow(),
+      tags: [["p", recipientPublicKey]],
+    },
+    randomKey
+  ) as Event
+}
+
+export function wrapEvent(event: Partial<UnsignedEvent>, senderPrivateKey: Uint8Array, recipientPublicKey: string) {
+
+  const rumor = createRumor(event, senderPrivateKey)
+
+  const seal = createSeal(rumor, senderPrivateKey, recipientPublicKey)
+  return createWrap(seal, recipientPublicKey)
+}
+
+export function unwrapEvent(wrap: Event, recipientPrivateKey: Uint8Array) {
+
+  const unwrappedSeal = nip44Decrypt(wrap, recipientPrivateKey)
+  return nip44Decrypt(unwrappedSeal, recipientPrivateKey)
+}