Files
xmrpay.link/api/check-short.php
Alexander Schmidt 2c3a8a0584 Security hardening: rate limiting, atomic locks, origin check, honest docs
API / Security:
- Add api/_helpers.php: shared send_security_headers(), verify_origin(),
  get_hmac_secret(), check_rate_limit(), read_json_locked(), write_json_locked()
- shorten.php: remove Access-Control-Allow-Origin:*, restrict to same-origin,
  rate-limit 20 req/h per IP, atomic JSON read+lock, HMAC secret from file
- verify.php: rate-limit GET (30/min) and POST (10/h) per IP, atomic lock,
  prevent overwriting existing proofs, origin check on POST
- node.php: fix rate limit from 1000 to 60 req/min, add security headers,
  origin check
- check-short.php: add security headers, re-derive signature server-side
- s.php: use file-based HMAC secret via get_hmac_secret(), hash_equals()
  for timing-safe comparison

Service Worker:
- sw.js: navigation requests (mode=navigate) never served from cache;
  network-first with offline fallback to prevent stale invoice state

Documentation (honest claims):
- README: tagline "No backend" -> "No tracking"; new Architecture table
  listing exactly what server sees for each feature; Security Model section
- index.html: meta description and footer updated from "No Backend" to
  "Minimal Backend"
- i18n.js footer: already updated in previous commit
2026-03-26 07:13:02 +01:00

55 lines
1.4 KiB
PHP

<?php
<?php
require_once __DIR__ . '/_helpers.php';
/**
* Short URL Integrity Verification API
* GET: Return the hash and HMAC signature for client-side verification.
*
* Security: Allows client-side detection of server-side tampering.
* The HMAC secret is stored in data/secret.key (auto-generated on first run).
*/
header('Content-Type: application/json');
send_security_headers();
if ($_SERVER['REQUEST_METHOD'] !== 'GET') {
http_response_code(405);
echo json_encode(['error' => 'Method not allowed']);
exit;
}
$code = $_GET['code'] ?? '';
if (empty($code) || !preg_match('/^[a-z0-9]{4,10}$/', $code)) {
http_response_code(400);
echo json_encode(['error' => 'Invalid code']);
exit;
}
$dbFile = __DIR__ . '/../data/urls.json';
if (!file_exists($dbFile)) {
http_response_code(404);
echo json_encode(['error' => 'Invoice not found']);
exit;
}
$urls = json_decode(file_get_contents($dbFile), true) ?: [];
if (!isset($urls[$code])) {
http_response_code(404);
echo json_encode(['error' => 'Invoice not found']);
exit;
}
$data = $urls[$code];
$hash = is_array($data) ? $data['h'] : $data;
$signature = is_array($data) ? $data['s'] : null;
// Re-derive expected signature so client can verify
$expected = $signature ? hash_hmac('sha256', $hash, get_hmac_secret()) : null;
echo json_encode([
'code' => $code,
'hash' => $hash,
'signature' => $expected
]);