01 Security
Small data surface. Strict handoff boundary.
Zulde is designed around what it refuses to retain: no files, no downstream destinations, and no generated one-time links.
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02 Detail
Built around a smaller access surface.
Encrypted recipient records
Recipient emails use authenticated encryption with unique nonces. Codes and lookup values use keyed hashes backed by server-only peppers.
- Independent keys
- No plaintext fallback
- One email per code
Signed and constrained
The shared service receives a signed encrypted UID over HTTPS. Returned URLs must match one configured host and token shape.
- Timestamp and nonce
- Short request timeout
- Fail-closed validation
Guessing resistance
Application and nginx rate controls enforce rolling limits. Public failures do not reveal code status or recipient existence.
- Network buckets
- Code buckets
- Temporary lockouts
Secrets stay outside the release
Database, API, encryption, DNS, and handoff credentials live in a root-readable environment file or managed secret store.
- No source fallbacks
- One-time API key reveal
- Rotation-ready configuration