feat(payment): verify Razorpay checkout callbacks

packages/payment/package.json

@@ -1,6 +1,6 @@
 {
   "name": "@wrnexus/payment",
-  "version": "0.8.1",
+  "version": "0.8.2",
   "private": true,
   "type": "module",
   "main": "src/index.ts",

packages/payment/src/adapters.ts

@@ -343,6 +343,23 @@ export interface RazorpayConfig {
   webhookSecret: string;
   theme?: { color?: string };
 }
+export interface RazorpayCheckoutResult {
+  orderId: string;
+  paymentId: string;
+  signature: string;
+}
+
+/** Verify the signed result returned by Razorpay Standard Checkout. */
+export async function verifyRazorpayCheckoutSignature(
+  result: RazorpayCheckoutResult,
+  keySecret: string,
+) {
+  if (!result.orderId || !result.paymentId || !result.signature || !keySecret) return false;
+  return equal(
+    result.signature.toLowerCase(),
+    await hmac(`${result.orderId}|${result.paymentId}`, keySecret),
+  );
+}
 export function razorpayGateway(config: RazorpayConfig): PaymentGateway<RazorpayConfig> {
   const auth = `Basic ${btoa(`${config.keyId}:${config.keySecret}`)}`;
   const request = (path: string, init: RequestInit = {}) =>

packages/payment/test/adapter-contract.test.ts

@@ -3,6 +3,7 @@ import {
   exerciseGatewayContract,
   paypalGateway,
   razorpayGateway,
+  verifyRazorpayCheckoutSignature,
   sandboxGateway,
   signSandboxWebhook,
   stripeGateway,
@@ -180,6 +181,22 @@ test("shared executable contract drives Razorpay through its HTTP adapter", asyn
   expect(report).toEqual({ ok: true, issues: [] });
 });
 
+test("Razorpay checkout signatures are verified without trusting browser data", async () => {
+  const secret = "checkout-secret";
+  const orderId = "order_1";
+  const paymentId = "pay_1";
+  const signed = await signature(`${orderId}|${paymentId}`, secret);
+  expect(
+    await verifyRazorpayCheckoutSignature({ orderId, paymentId, signature: signed }, secret),
+  ).toBe(true);
+  expect(
+    await verifyRazorpayCheckoutSignature(
+      { orderId, paymentId: "pay_tampered", signature: signed },
+      secret,
+    ),
+  ).toBe(false);
+});
+
 test("shared executable contract drives PayPal through its HTTP adapter", async () => {
   globalThis.fetch = (async (value, init) => {
     const url = String(value),