Add DM expiration functionality

2 files changed, 35 insertions, 11 deletions

diff --git a/src/lib/nip17.ts b/src/lib/nip17.ts
index 6cb8f9e3..9dd59f6f 100644
--- a/src/lib/nip17.ts
+++ b/src/lib/nip17.ts
@@ -10,20 +10,23 @@ const randomTimestamp = () => Math.floor(
 // If wrapPK is specified and different than receiverPK,
 // the message will be gift-wrapped to wrapPK
 // but the rumour will be sent to receiverPK.
-export const createNIP17MessageSK = (text: string, senderSK: Uint8Array, receiverPK: string, wrapPK: string = null) => {
+export const createNIP17MessageSK = (text: string, senderSK: Uint8Array, receiverPK: string, wrapPK: string = null, expiryDays: number = null) => {
     const rumour = createRumour(text, getPublicKey(senderSK), receiverPK);
     const sealed = sealRumourSK(rumour, senderSK, wrapPK || receiverPK);
-    return giftWrap(sealed, wrapPK || receiverPK);
+    return giftWrap(sealed, wrapPK || receiverPK, expiryDays);
 }
 
 // Create a NIP-17 message using NIP-07, requiring no sender secret key.
 // If wrapPK is specified and different than receiverPK,
 // the message will be gift-wrapped to wrapPK
 // but the rumour will be sent to receiverPK.
-export const createNIP17MessageNIP07 = async (text: string, senderPK: string, receiverPK: string, wrapPK: string = null) => {
+// If expiryDays is specified, the message will expire in that many days,
+// plus a random amount from 0 to 2 for security.
+// (expiration time = random creation time + expiryDays + 2 days)
+export const createNIP17MessageNIP07 = async (text: string, senderPK: string, receiverPK: string, wrapPK: string = null, expiryDays: number = null) => {
     const rumour = createRumour(text, senderPK, receiverPK);
     const sealed = await sealRumourNip07(rumour, wrapPK || receiverPK);
-    return giftWrap(sealed, wrapPK || receiverPK);
+    return giftWrap(sealed, wrapPK || receiverPK, expiryDays);
 }
 
 const createRumour = (text: string, senderPK: string, receiverPK: string) => {
@@ -68,16 +71,22 @@ const sealRumourNip07 = async (rumour: object, receiverPK: string) => {
     return window.nostr.signEvent(sealEvent);
 }
 
-const giftWrap = (event: object, receiverPK: string) => {
+const giftWrap = (event: object, receiverPK: string, expiryDays: number = null) => {
     const secretKey = generateSecretKey();
     const SKString = bytesToHex(secretKey);
     const conversationKey = u.getConversationKey(secretKey, receiverPK);
     const encryptedEvent = encrypt(JSON.stringify(event), conversationKey);
+    const created = randomTimestamp();
+    const tags = [["p", receiverPK]];
+    if (expiryDays != null) {
+        const expiration = created + (expiryDays + 2) * 86400;
+        tags.push(["expiration", expiration.toString()]);
+    }
 
     const giftWrapEvent = {
         kind: 1059, // gift wrap
-        created_at: randomTimestamp(),
-        tags: [["p", receiverPK]],
+        created_at: created,
+        tags: tags,
         pubkey: getPublicKey(secretKey),
         content: encryptedEvent
     }
diff --git a/src/routes/(app)/dm/[recipient]/+page.svelte b/src/routes/(app)/dm/[recipient]/+page.svelte
index 9bebae92..e0702bc3 100644
--- a/src/routes/(app)/dm/[recipient]/+page.svelte
+++ b/src/routes/(app)/dm/[recipient]/+page.svelte
@@ -61,6 +61,15 @@
    return relays;
  }
 
+ const expired = (event: object) => {
+   for (const tag of event.tags) {
+     if (tag[0] == "expiration") {
+       return (Date.now() / 1000) >= Number(tag[1]);
+     }
+   }
+   return false;
+ }
+
  const loadEvents = async (relays: string[]) => {
    const wrapped = await pool.querySync(
      relays, { kinds: [1059], "#p": [user.pubkey], limit: DM_FETCH_LIMIT }
@@ -69,9 +78,11 @@
    // intentionally decrypting sequentially to avoid having a bunch of popups
    let decryptedRumours = new Map();
    for (event of wrapped) {
-     const rumour = await decryptMessage(event);
-     const created = Math.floor(rumour.created_at / 86400);
-     appendMultimap(decryptedRumours, created, rumour);
+     if (!expired(event)) {
+       const rumour = await decryptMessage(event);
+       const created = Math.floor(rumour.created_at / 86400);
+       appendMultimap(decryptedRumours, created, rumour);
+     } else console.log("relay contains expired event", event.id);
    }
    for (const [date, event] of decryptedRumours) {
      event.sort((ev1, ev2) => ev1.created_at - ev2.created_at);
@@ -107,11 +118,15 @@
        message, user.pubkey, recipient.pubkey, user.pubkey);
    } else {
      const sk = await getPrivateKey(user);
-     event1 = libnip17.createNIP17MessageSK(message, sk, recipient.pubkey);
+     event1 = libnip17.createNIP17MessageSK(
+       message, sk, recipient.pubkey);
      event2 = libnip17.createNIP17MessageSK(
        message, sk, recipient.pubkey, user.pubkey);
    }
 
+   console.log(Date.now() / 1000);
+   console.log(event2.tags);
+
    const recipientRelays = await getPreferredRelays(recipient.pubkey);
    const p1 = Promise.any(pool.publish(recipientRelays, event1));
    const senderRelays = await getPreferredRelays(user.pubkey);