ETHOS Chat

ETHOS is a secure web app for one-to-one chat, group chat, and file transfer. It uses hybrid quantum-safe key exchange, direct WebRTC when possible, and encrypted relay fallback when networks get in the way.

ETHOS is built around a narrow rule: user content must never fall back to plaintext. If a direct browser-to-browser path cannot be established, ETHOS uses encrypted relay transport instead of weakening the content encryption model.

ETHOS sessions use hybrid key agreement:

• ECDH P-256 for a widely deployed classical elliptic-curve component.
• ML-KEM-1024 for a post-quantum component selected by NIST.

The session design is hybrid: both components contribute to the secure session. This protects against ordinary classical attackers today while reducing exposure to future harvest-now-decrypt-later attacks.

Messages use a Double Ratchet construction with AES-256-GCM message encryption. Message keys evolve over time, so one exposed message key should not unlock the entire conversation history.

ETHOS does not intentionally provide a plaintext transport mode for user content. When direct WebRTC is available, encrypted content moves over the direct peer path. When direct WebRTC is not available, encrypted content may move through relay fallback.