Secure messaging — AES-256 encryption with an 11-digit key
Both sender and receiver must use the same key.
1. Pick an 11-digit key. Any 11 numeric digits. Share it with your recipient over a separate channel — LinkedIn message, voice call, anything other than the same channel the encrypted message will travel on.
2. Type your message and press Encrypt. The Hartley Cipher uses AES-256-GCM (the same encryption standard used by banks and governments) with PBKDF2 key derivation.
3. Copy the gibberish output and send it however you like. WhatsApp, Signal, email, or written on a postcard. Only someone with the key can decode it.
4. To decrypt, paste the gibberish back in, enter the key, press Decrypt.
This is the same encryption system David Hartley built for his daughter Emma in The Last Warhead — the real, working version. Your message never leaves your browser. Nothing is sent to a server. Nothing is logged.