End-to-end encryption

EmailApp uses a Proton-style zero-access model. The server stores ciphertext only. Your password unlocks keys on this device — we cannot read your mail.

🔒 E2EE mailbox

AES-256-GCM content keys wrapped with ECDH P-256. Private keys password-wrapped at rest on the server.

💾 Offline .emap files

Saved messages are password-protected containers. Only EmailApp can open them. Expired, over-opened, or lease-revoked files are wiped by the app.

💣 Self-destruct policy

Optional TTL, max opens, and online lease. Other apps only see unreadable bytes — cryptographically dead without our unlock path.

Honest limits

  • If you lose your password and recovery kit, mail cannot be recovered (by design).
  • Malware on an unlocked device can still read decrypted content in memory.
  • Files do not magically erase themselves without the OS running our wipe logic — but without EmailApp + password they remain useless ciphertext.

Full design: docs/E2EE.md