support for nip44

README.md

@@ -10,12 +10,16 @@ This allows you to sign [Nostr](https://github.com/fiatjaf/nostr) events on web-
 
 It provides a `window.nostr` object which has the following methods:
 
-```
+```javascript
 async window.nostr.getPublicKey(): string // returns your public key as hex
 async window.nostr.signEvent(event): Event // returns the full event object signed
 async window.nostr.getRelays(): { [url: string]: RelayPolicy } // returns a map of relays
+
 async window.nostr.nip04.encrypt(pubkey, plaintext): string // returns ciphertext+iv as specified in nip04
 async window.nostr.nip04.decrypt(pubkey, ciphertext): string // takes ciphertext+iv as specified in nip04
+
+async window.nostr.nip44.encrypt(pubkey, plaintext): string // takes pubkey, plaintext, returns ciphertext as specified in nip-44
+async window.nostr.nip44.decrypt(pubkey, ciphertext): string // takes pubkey, ciphertext, returns plaintext as specified in nip-44
 ```
 
 ## Install

src/LRUCache.ts

@@ -0,0 +1,42 @@
+export class LRUCache<K, V> {
+  private maxSize: number;
+  private map: Map<K, V>;
+  private keys: any[];
+
+  constructor(maxSize) {
+    this.maxSize = maxSize;
+    this.map = new Map();
+    this.keys = [];
+  }
+
+  clear() {
+    this.map.clear();
+  }
+
+  has(k) {
+    return this.map.has(k);
+  }
+
+  get(k) {
+    const v = this.map.get(k);
+
+    if (v !== undefined) {
+      this.keys.push(k);
+
+      if (this.keys.length > this.maxSize * 2) {
+        this.keys.splice(-this.maxSize);
+      }
+    }
+
+    return v;
+  }
+
+  set(k, v) {
+    this.map.set(k, v);
+    this.keys.push(k);
+
+    if (this.map.size > this.maxSize) {
+      this.map.delete(this.keys.shift());
+    }
+  }
+}

src/background.ts

@@ -3,13 +3,15 @@ import {
   validateEvent,
   finalizeEvent,
   getEventHash,
-  getPublicKey
+  getPublicKey,
+  nip44
 } from 'nostr-tools';
 import { nip04, EventTemplate } from 'nostr-tools';
 
 import * as Storage from './storage';
 import { AuthorizationCondition, PromptResponse } from './types';
 import { PERMISSIONS_REQUIRED, convertHexToUint8Array } from './common';
+import { LRUCache } from './LRUCache';
 
 let openPrompt: { resolve: Function; reject: Function } | null = null;
 
@@ -105,6 +107,16 @@ async function handleContentScriptMessage({ type, params, host }) {
         let { peer, ciphertext } = params;
         return nip04.decrypt(sk, peer, ciphertext);
       }
+      case 'nip44.encrypt': {
+        const { peer, plaintext } = params;
+        const key = getSharedSecret(sk, peer);
+        return nip44.v2.decrypt(plaintext, key);
+      }
+      case 'nip44.decrypt': {
+        const { peer, ciphertext } = params;
+        const key = getSharedSecret(sk, peer);
+        return nip44.v2.decrypt(ciphertext, key);
+      }
     }
   } catch (error) {
     return { error: { message: error.message, stack: error.stack } };
@@ -186,3 +198,22 @@ function promptPermission(host, level, params) {
 async function readPermissionLevel(host: string): Promise<number> {
   return (await Storage.readActivePermissions())[host]?.level || 0;
 }
+
+// prepare a cache of the last 100 shared keys used
+const secretsCache = new LRUCache<string, Uint8Array>(100);
+let previousSk: Uint8Array | null = null;
+function getSharedSecret(sk: Uint8Array, peer: string) {
+  // Detect a private key change and erase the cache if they changed their key
+  if (previousSk !== sk) {
+    secretsCache.clear();
+  }
+
+  let key = secretsCache.get(peer);
+
+  if (!key) {
+    key = nip44.v2.utils.getConversationKey(sk, peer);
+    secretsCache.set(peer, key);
+  }
+
+  return key;
+}

src/common.ts

@@ -19,7 +19,9 @@ const PERMISSION_NAMES = {
   getRelays: 'read your list of preferred relays',
   signEvent: 'sign events using your private key',
   'nip04.encrypt': 'encrypt messages to peers',
-  'nip04.decrypt': 'decrypt messages from peers'
+  'nip04.decrypt': 'decrypt messages from peers',
+  'nip44.encrypt': 'encrypt messages to peers (nip44)',
+  'nip44.decrypt': 'decrypt messages from peers (nip44)'
 };
 
 export function getAllowedCapabilities(permission): string[] {

src/nostr-provider.ts

@@ -29,6 +29,16 @@ window.nostr = {
     }
   },
 
+  nip44: {
+    async encrypt(peer, plaintext) {
+      return window.nostr._call('nip44.encrypt', { peer, plaintext });
+    },
+
+    async decrypt(peer, ciphertext) {
+      return window.nostr._call('nip44.decrypt', { peer, ciphertext });
+    }
+  },
+
   _call(type, params) {
     let id = Math.random().toString().slice(-4);
     console.log(