Webhook

POST /your/endpoint HTTP/1.1
Content-Type: application/json
User-Agent: SmsGrab-Webhooks/1.0
SmsGrab-Event: activation.code_received
SmsGrab-Delivery: 9f7d6c1e-2b44-4c1a-8f0e-6a3d2c1b0e9f
SmsGrab-Signature: t=1790503200,v1=3b9a0c…

{ "id": "evt_4e1f…", "type": "activation.code_received", "created_at": "2026-09-27T10:06:12.004Z",
  "api_version": "2026-09-27", "data": { "activation": { "id": "5c1d0c2e-…", "status": "CODE_RECEIVED" } } }

[$t, $v1] = (function (string $h): array {
    parse_str(str_replace(',', '&', $h), $p);
    return [(int) ($p['t'] ?? 0), (string) ($p['v1'] ?? '')];
})($_SERVER['HTTP_SMSGRAB_SIGNATURE'] ?? '');
$body = file_get_contents('php://input');
$expected = hash_hmac('sha256', $t.'.'.$body, getenv('SMSGRAB_WEBHOOK_SECRET'));
$ok = abs(time() - $t) <= 300 && hash_equals($expected, $v1);

import hmac, hashlib, time

def verify(header: str, body: bytes, secret: str) -> bool:
    parts = dict(p.split("=", 1) for p in header.split(","))
    t = int(parts.get("t", "0"))
    expected = hmac.new(secret.encode(), f"{t}.".encode() + body, hashlib.sha256).hexdigest()
    return abs(time.time() - t) <= 300 and hmac.compare_digest(expected, parts.get("v1", ""))

import crypto from 'node:crypto';

export function verify(header, rawBody, secret) {
  const parts = Object.fromEntries(header.split(',').map((p) => p.split('=')));
  const t = Number(parts.t ?? 0);
  const expected = crypto.createHmac('sha256', secret).update(`${t}.`).update(rawBody).digest('hex');
  const given = Buffer.from(parts.v1 ?? '', 'utf8');
  return Math.abs(Date.now() / 1000 - t) <= 300 && given.length === expected.length
    && crypto.timingSafeEqual(Buffer.from(expected, 'utf8'), given);
}