Glossary
What is end-to-end encryption (E2EE)?
End-to-end encryption means only the sender and recipient can read a message; everything in between - including any server - sees only ciphertext.
The message is encrypted on the sender’s device and decrypted only on the recipient’s, using keys that never leave those devices. No provider in the middle can read it.
PrivaMesh goes further than typical E2EE apps: because there is no server in the middle at all, the only "ends" that exist are the two devices. It uses X3DH, the Double Ratchet and AES-256-GCM to seal every message.
The term is precise and frequently misused. End-to-end means the keys exist only on the endpoint devices. Encrypted in transit means TLS to a server that then holds plaintext. Encrypted at rest means the provider stores it encrypted with keys the provider also holds. Only the first excludes the provider from reading your messages.
A useful test: if the service can show you your full message history on a new device after you log in with a password, it is not end-to-end encrypted in a meaningful sense, because something other than your device was able to decrypt it. Convenience features and end-to-end encryption pull in opposite directions.
PrivaMesh takes the definition literally. There is no server between the ends at all, so the two devices are the only places keys or plaintext ever exist. X3DH establishes the shared secret, the Double Ratchet derives a fresh key per message, and AES-256-GCM seals the payload with tamper detection.
Primary sources
- X3DH key agreement protocolThe specification for the Extended Triple Diffie-Hellman handshake, by Marlinspike and Perrin.
- NIST SP 800-38D: Galois/Counter ModeThe NIST recommendation defining AES-GCM, the authenticated encryption PrivaMesh uses to seal payloads.