Cloudflare Developers•4mo ago

TypeScript node:crypto timingSafeEqual function not found

I'm trying to implement Twitch EventSub webhook handler in my Worker based on Twitch example code https://dev.twitch.tv/docs/eventsub/handling-webhook-events/#simple-nodejs-example It uses crypto library functions createHmac and timingSafeEqual Reading cloudflare docs I understood that I need to use node:crypto and the docs says that both createHmac and timingSafeEqual are supported in https://developers.cloudflare.com/workers/runtime-apis/nodejs/crypto/ So I created a new worker project as described here https://developers.cloudflare.com/workers/get-started/guide/#1-create-a-new-worker-project by running npm create cloudflare@latest and selecting "Hello World" Worker as template and Yes for TypeScript support I then modified src/index.ts (didn't change anything else) for testing purposes with this:

import { createHmac, timingSafeEqual } from 'node:crypto';
import { Buffer } from 'node:buffer';

// Prepend this string to the HMAC that's created from the message
const HMAC_PREFIX = 'sha256=';

// Verify whether our hash matches the hash that Twitch passed in the header.
function verifyMessage(hmac, verifySignature) {
    return timingSafeEqual(Buffer.from(hmac), Buffer.from(verifySignature));
}

export default {
    async fetch(request: Request, env: Env, ctx: ExecutionContext): Promise<Response> {
        const hmac = HMAC_PREFIX + createHmac('sha256', 'MySecret')
            .update('MyMessage')
            .digest('hex');

        if (verifyMessage(hmac, hmac)) {
            console.log('timingSafeEqual true');
        } else {
            console.log('timingSafeEqual false');
        }

        return new Response('');
    }
};

import { createHmac, timingSafeEqual } from 'node:crypto';
import { Buffer } from 'node:buffer';

// Prepend this string to the HMAC that's created from the message
const HMAC_PREFIX = 'sha256=';

// Verify whether our hash matches the hash that Twitch passed in the header.
function verifyMessage(hmac, verifySignature) {
    return timingSafeEqual(Buffer.from(hmac), Buffer.from(verifySignature));
}

export default {
    async fetch(request: Request, env: Env, ctx: ExecutionContext): Promise<Response> {
        const hmac = HMAC_PREFIX + createHmac('sha256', 'MySecret')
            .update('MyMessage')
            .digest('hex');

        if (verifyMessage(hmac, hmac)) {
            console.log('timingSafeEqual true');
        } else {
            console.log('timingSafeEqual false');
        }

        return new Response('');
    }
};

Then I ran npm run start and opened the local worker page, but in console I see this: [wrangler:err] TypeError: timingSafeEqual is not a function Why? The documenation says that timingSafeEqual is supported. Am I missing something?

5 Replies

Hello, I’m Allie!•4mo ago

Did you do this part?

To use Node.js APIs in your Worker, add the nodejs_compat compatibility flag to your wrangler.toml file.

q_p•4mo ago

I didn't change anything besides the src/index.ts after running npm create cloudflare@latest with hello world and typescript options selected Looking at my wrangler.toml it's already set to:

compatibility_date = "2024-05-12"
compatibility_flags = ["nodejs_compat"]

compatibility_date = "2024-05-12"
compatibility_flags = ["nodejs_compat"]

So it should be working? The createHmac is working, but timingSafeEqual is throwing error Anyone? Pls? Is the documentation wrong and timingSafeEqual isn't actually supported? Hello, pls halp 😦 should I create a bug report on github instead?

Hello, I’m Allie!•4mo ago

Sorry about that. Found it, going to make an issue now...

Hello, I’m Allie!•4mo ago

https://github.com/cloudflare/workerd/issues/2172

GitHub

🐛 [bug] crypto.timingSafeEqual === undefined · Issue #2172 · cl...

Versions wrangler@3.57.1 miniflare@3.20240512.0 workerd@1.20240512.0 Issue According to Misc | Node Crypto, the timingSafeEqual function should be supported by nodejs_compat. However, when logging ...

q_p•4mo ago

Thank you

Gaming

Programming

TypeScript node:crypto timingSafeEqual function not found