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
- Implement HMAC-SHA256 signatures on short URLs to detect server-side tampering
- Add client-side signature verification with hostname-derived secret
- New API endpoint: /api/check-short.php for integrity verification
- Update verify.php with privacy notice (addresses not stored)
- Update README to clarify minimal backend requirement (short URLs, rate caching, proof storage)
- Add toast warning when signature mismatch detected
- Support both old and new format in s.php for backward compatibility
- Update all i18n translations (EN, DE, FR, IT, ES, PT, RU)
Addresses security concern: Server compromise could previously result in address
substitution for short-linked invoices. Now client-side verification detects tampering.
- XMR address validation (standard, subaddress, integrated)
- Amount in XMR/EUR/USD/CHF with CoinGecko conversion
- QR code generation with monero: URI
- Shareable short URLs (/s/abc123) via self-hosted PHP backend
- i18n (DE/EN) with browser language detection
- Service worker for offline capability
- Dark mode, responsive design
