feat: add TS3 identity generation with Ed25519 keypairs

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

src/ts-protocol/identity.test.ts

@@ -0,0 +1,28 @@
+import { describe, it, expect } from "vitest";
+import { generateIdentity, exportIdentity, importIdentity } from "./identity.js";
+
+describe("TS3 Identity", () => {
+  it("generates a valid identity with keypair", () => {
+    const identity = generateIdentity();
+    expect(identity.publicKey).toBeInstanceOf(Uint8Array);
+    expect(identity.privateKey).toBeInstanceOf(Uint8Array);
+    expect(identity.publicKey.length).toBe(32);
+    expect(identity.privateKey.length).toBe(64);
+    expect(identity.uid).toBeTruthy();
+    expect(typeof identity.uid).toBe("string");
+  });
+
+  it("exports and imports identity consistently", () => {
+    const identity = generateIdentity();
+    const exported = exportIdentity(identity);
+    const imported = importIdentity(exported);
+    expect(imported.uid).toBe(identity.uid);
+    expect(imported.publicKey).toEqual(identity.publicKey);
+  });
+
+  it("generates unique identities each time", () => {
+    const id1 = generateIdentity();
+    const id2 = generateIdentity();
+    expect(id1.uid).not.toBe(id2.uid);
+  });
+});

src/ts-protocol/identity.ts

@@ -0,0 +1,37 @@
+import nacl from "tweetnacl";
+import crypto from "node:crypto";
+
+export interface TS3Identity {
+  publicKey: Uint8Array;
+  privateKey: Uint8Array;
+  uid: string; // base64-encoded SHA1 of public key
+}
+
+export function generateIdentity(): TS3Identity {
+  const keypair = nacl.sign.keyPair();
+  const uid = computeUid(keypair.publicKey);
+  return {
+    publicKey: keypair.publicKey,
+    privateKey: keypair.secretKey,
+    uid,
+  };
+}
+
+export function computeUid(publicKey: Uint8Array): string {
+  return crypto.createHash("sha1").update(publicKey).digest("base64");
+}
+
+export function exportIdentity(identity: TS3Identity): string {
+  return JSON.stringify({
+    publicKey: Buffer.from(identity.publicKey).toString("base64"),
+    privateKey: Buffer.from(identity.privateKey).toString("base64"),
+  });
+}
+
+export function importIdentity(data: string): TS3Identity {
+  const parsed = JSON.parse(data) as { publicKey: string; privateKey: string };
+  const publicKey = new Uint8Array(Buffer.from(parsed.publicKey, "base64"));
+  const privateKey = new Uint8Array(Buffer.from(parsed.privateKey, "base64"));
+  const uid = computeUid(publicKey);
+  return { publicKey, privateKey, uid };
+}