news.volyx.in

Signal Protocol and Post-Quantum Ratchets (signal.org)

637 points by pluto_modadic · 297 days ago · 287 comments on HN

Article summary

The Signal Protocol has introduced a new post-quantum ratchet called the Sparse Post Quantum Ratchet (SPQR) to enhance its security against future quantum computing threats. This new ratchet provides secure messaging that achieves forward secrecy and post-compromise security guarantees in a quantum-safe manner. The SPQR is mixed with Signal's existing Double Ratchet to create a Triple Ratchet, which will be rolled out to all conversations without requiring user action. This update aims to protect communications both now and in the event of cryptographically relevant quantum computers becoming a reality.

Main themes

  • Post-Quantum Cryptography
  • Signal Protocol Security
  • Forward Secrecy
  • Post-Compromise Security
  • Quantum Computing Threats

What commenters say

  • The introduction of the SPQR is a significant advancement in the security of the Signal Protocol, providing protection against future quantum computing threats.
  • The use of a static symmetric key for backups undermines the forward secrecy and post-compromise security guarantees of the Signal Protocol.
  • The risk of quantum computers breaking current encryption methods is a concern, but the impact on symmetric encryption like AES is still uncertain.
  • The Signal Protocol's security features, including forward secrecy and post-compromise security, are compromised by the inclusion of disappearing messages in backups.
  • The concept of disappearing messages is not a cryptographic feature, but rather an opsec feature for trusted counterparties.
  • The use of post-quantum cryptography is necessary to maintain the security guarantees of the Signal Protocol in the face of future quantum computing threats.
  • The implementation of backups in Signal may undo the benefits of forward secrecy and post-compromise security, making the protocol's security features less effective.
  • The threat model of quantum computers is not the primary concern, but rather the general security and trust of the Signal Protocol and its features.