TextSecure Protocol - Present and Future

Explore the TextSecure protocol for end-to-end encrypted messaging in this NorthSec 2015 conference talk by Trevor Perrin. Delve into cryptographic challenges like forward secrecy, multi-party and multi-device scenarios, and authentication. Learn about the protocol's structure, including stateful sessions, public key encryption, and key agreement methods. Examine the Axolotl ratchet, message exchange process, and approaches to multi-party and multi-device communication. Gain insights into potential future developments in use cases, authentication, federation, and metadata protection for secure messaging systems.

Intro
Open Whisper Systems . Founded by Moxie Marlinspike • Goal of making private communications simple
Security goals and model
Overview
Stateful protocol • First message creates a session based on keys from a key directory
Public key encryption
Signed prekeys
Signed & one-time prekeys
Key agreement
Diffie-Hellman encryption
Diffie-Hellman authentication
Symmetric-key ratchet
DH ratchet
Axolotl ratchet
Alice's initial message
Bob's response
Alice's response
Multi-party (sender keys)
Multi-device
End-To-End encryption and
Authenticating public keys