add advert parser and verifier

package-lock.json

@@ -7,7 +7,35 @@
     "": {
       "name": "@liamcottle/meshcore.js",
       "version": "1.0.9",
-      "license": "MIT"
+      "license": "MIT",
+      "dependencies": {
+        "@noble/curves": "^1.8.1"
+      }
+    },
+    "node_modules/@noble/curves": {
+      "version": "1.8.1",
+      "resolved": "https://registry.npmjs.org/@noble/curves/-/curves-1.8.1.tgz",
+      "integrity": "sha512-warwspo+UYUPep0Q+vtdVB4Ugn8GGQj8iyB3gnRWsztmUHTI3S1nhdiWNsPUGL0vud7JlRRk1XEu7Lq1KGTnMQ==",
+      "dependencies": {
+        "@noble/hashes": "1.7.1"
+      },
+      "engines": {
+        "node": "^14.21.3 || >=16"
+      },
+      "funding": {
+        "url": "https://paulmillr.com/funding/"
+      }
+    },
+    "node_modules/@noble/hashes": {
+      "version": "1.7.1",
+      "resolved": "https://registry.npmjs.org/@noble/hashes/-/hashes-1.7.1.tgz",
+      "integrity": "sha512-B8XBPsn4vT/KJAGqDzbwztd+6Yte3P4V7iafm24bxgDe/mlRuK6xmWPuCNrKt2vDafZ8MfJLlchDG/vYafQEjQ==",
+      "engines": {
+        "node": "^14.21.3 || >=16"
+      },
+      "funding": {
+        "url": "https://paulmillr.com/funding/"
+      }
     }
   }
 }

package.json

@@ -8,5 +8,8 @@
     "test": "echo \"Error: no test specified\" && exit 1"
   },
   "author": "Liam Cottle <liam@liamcottle.com>",
-  "license": "MIT"
+  "license": "MIT",
+  "dependencies": {
+    "@noble/curves": "^1.8.1"
+  }
 }

src/advert.js

@@ -0,0 +1,44 @@
+import { ed25519 } from "@noble/curves/ed25519";
+import BufferReader from "./buffer_reader.js";
+import Packet from "./packet.js";
+
+class Advert {
+
+    constructor(publicKey, timestamp, signature, appData) {
+        this.publicKey = publicKey;
+        this.timestamp = timestamp;
+        this.signature = signature;
+        this.appData = appData;
+    }
+
+    getTimestamp() {
+        return (new BufferReader(this.timestamp)).readUInt32LE();
+    }
+
+    isVerified() {
+        return ed25519.verify(this.signature, Buffer.concat([
+            this.publicKey,
+            this.timestamp,
+            this.appData,
+        ]), this.publicKey);
+    }
+
+    static fromPacketBytes(bytes) {
+
+        // parse packet from bytes
+        const packet = Packet.fromBytes(bytes);
+
+        // read packet payload
+        const bufferedReader = new BufferReader(packet.payload);
+        const publicKey = bufferedReader.readBytes(32);
+        const timestamp = bufferedReader.readBytes(4); // read as bytes for signature
+        const signature = bufferedReader.readBytes(64);
+        const appData = bufferedReader.readRemainingBytes();
+
+        return new Advert(publicKey, timestamp, signature, appData);
+
+    }
+
+}
+
+export default Advert;