Verify signatures

import crypto from "node:crypto";
import express from "express";

const app = express();
const SECRET = process.env.TELLEO_WEBHOOK_SECRET;

// express.raw keeps the exact bytes Telleo signed.
app.post("/telleo/webhook", express.raw({ type: "application/json" }), (req, res) => {
  const header = req.get("Telleo-Signature") || "";
  const parts = Object.fromEntries(header.split(",").map((p) => p.split("=")));
  const t = Number(parts.t);
  const expected = crypto
    .createHmac("sha256", SECRET)
    .update(`${parts.t}.${req.body}`)
    .digest("hex");

  const fresh = Math.abs(Date.now() / 1000 - t) < 300;
  const valid =
    parts.v1 &&
    parts.v1.length === expected.length &&
    crypto.timingSafeEqual(Buffer.from(parts.v1), Buffer.from(expected));
  if (!fresh || !valid) return res.status(400).send("bad signature");

  const event = JSON.parse(req.body);
  res.sendStatus(200); // answer first
  handleEvent(event);  // then do the work
});

import hashlib, hmac, os, time
from flask import Flask, request, abort

app = Flask(__name__)
SECRET = os.environ["TELLEO_WEBHOOK_SECRET"].encode()

@app.post("/telleo/webhook")
def telleo_webhook():
    raw = request.get_data()  # raw bytes, before any JSON parsing
    parts = dict(p.split("=", 1) for p in request.headers.get("Telleo-Signature", "").split(",") if "=" in p)
    t, sig = parts.get("t", ""), parts.get("v1", "")
    expected = hmac.new(SECRET, t.encode() + b"." + raw, hashlib.sha256).hexdigest()
    if not t.isdigit() or abs(time.time() - int(t)) > 300 or not hmac.compare_digest(sig, expected):
        abort(400)
    event = request.get_json()
    queue_for_processing(event)  # keep the response fast
    return "", 200

<?php
$secret = getenv('TELLEO_WEBHOOK_SECRET');
$raw = file_get_contents('php://input');
$parts = [];
foreach (explode(',', $_SERVER['HTTP_TELLEO_SIGNATURE'] ?? '') as $p) {
    [$k, $v] = array_pad(explode('=', $p, 2), 2, '');
    $parts[$k] = $v;
}
$expected = hash_hmac('sha256', ($parts['t'] ?? '') . '.' . $raw, $secret);
if (abs(time() - (int)($parts['t'] ?? 0)) > 300 || !hash_equals($expected, $parts['v1'] ?? '')) {
    http_response_code(400);
    exit;
}
$event = json_decode($raw, true);
http_response_code(200);
// process $event

import javax.crypto.Mac;
import javax.crypto.spec.SecretKeySpec;
import java.nio.charset.StandardCharsets;
import java.security.MessageDigest;
import java.util.HexFormat;

static boolean verify(String secret, String header, byte[] rawBody) throws Exception {
    String t = null, v1 = null;
    for (String p : header.split(",")) {
        String[] kv = p.split("=", 2);
        if (kv.length == 2 && kv[0].equals("t")) t = kv[1];
        if (kv.length == 2 && kv[0].equals("v1")) v1 = kv[1];
    }
    if (t == null || v1 == null) return false;
    if (Math.abs(System.currentTimeMillis() / 1000 - Long.parseLong(t)) > 300) return false;
    Mac mac = Mac.getInstance("HmacSHA256");
    mac.init(new SecretKeySpec(secret.getBytes(StandardCharsets.UTF_8), "HmacSHA256"));
    mac.update((t + ".").getBytes(StandardCharsets.UTF_8));
    String expected = HexFormat.of().formatHex(mac.doFinal(rawBody));
    return MessageDigest.isEqual(expected.getBytes(StandardCharsets.UTF_8), v1.getBytes(StandardCharsets.UTF_8));
}