Signal has introduced the Sparse Post Quantum Ratchet (SPQR) to enhance the Signal Protocol's security against potential quantum computing threats, while preserving existing features like forward secrecy and post-compromise security. This new ratchet works alongside the existing Double Ratchet to ensure secure messaging that remains resilient even in the face of future quantum attacks. Users will experience no changes in their app, as the transition to this protocol will occur automatically.

The article reviews the cryptographic techniques employed by the Signal messaging app, highlighting its commitment to user privacy and security. It delves into the specific algorithms and protocols that underpin Signal's encryption, emphasizing the importance of robust cryptography in protecting user communications. Additionally, it discusses potential vulnerabilities and the app's response to security challenges.

Meredith Whittaker discusses the surprising reaction of people learning that Signal operates partly on AWS, emphasizing the importance of encryption that ensures user communications remain private and inaccessible to anyone, including AWS and Signal itself. She expresses concern over the public's lack of understanding regarding this aspect of Signal's infrastructure.