Agni's Capsule is architected so that the backend server, database administrators, and third-party hosting providers cannot decrypt the personal correspondence, voice notes, or photos sealed inside capsules.
| Component | Standard / Algorithm | Parameters |
|---|---|---|
| Content Encryption | AES-GCM | 256-bit symmetric key, 12-byte IV, 128-bit authentication tag |
| Key Derivation | PBKDF2-HMAC-SHA256 | 100,000 iterations, 16-byte random salt |
| Key Agreement / Wrapping | SubtleCrypto WrapKey / PBKDF2 | AES-GCM wrapping of 256-bit capsule keys |
| Archival Digest | SHA-256 | 256-bit hex fingerprint string (e.g. 0x8F92...B3) |
| Password Storage | PBKDF2-HMAC-SHA256 / Argon2id | 16-byte cryptographically random salt, 100,000 iterations |
| Session Tokens | JWT (HMAC-SHA256) | Short-lived access tokens (24h) + protected 30-day refresh tokens |
- Lost Keys: If an author loses both their account passphrase and all exported recovery key backups, the encrypted ciphertext stored in their vault cannot be unsealed.
- Notification Privacy: Outbound notification payloads (email and push) never contain decrypted plaintext message excerpts or sensitive media. Notifications contain only generic arrival links.
- Temporal Enforcement: The server refuses to serve envelope keys or ciphertexts for unreleased capsules to recipients until
delivery_time_utc <= now. - Sovereign Drive Permission Scope: Google Drive OAuth permissions strictly request
https://www.googleapis.com/auth/drive.file. The app can only see and access files it specifically created inside the user's/Encrypted-Memory-Capsulesdirectory.