Verify simple implementation to verify a GitHub webhook payload in TypeScript using NodeJs and Restify

github-webhook.ts

import * as Restify from "restify"
import * as Crypto from "crypto"

type GithubWebRepository = {
    id: number
    name: string
    full_name: string
    private: boolean
    git_url: string
    ssh_url: string
}

type GitHubWebhookPayload = {
    ref: string
    repository: GithubWebRepository
}

// Webhook secret
const WEBHOOK_SECRET = "1234secret"

// Configure the server
const server = Restify.createServer();
server.use(Restify.plugins.bodyParser())

server.post('/', (req, res, next) => {
    let body: GitHubWebhookPayload = req.body
    let signature = req.header('X-Hub-Signature')
    let event = req.header('X-GitHub-Event')

    // Verify the signature
    let hmac = Crypto.createHmac("sha1", WEBHOOK_SECRET)
    let calculatedSignature = "sha1=" + hmac.update(JSON.stringify(req.body)).digest("hex");

    if (calculatedSignature !== signature) {
        return res.send(401)
    }

    res.send(req.body)
});

server.listen(80, function () {
    console.log('%s listening at %s', server.name, server.url);
});