The Signal Protocol is a set of cryptographic specifications that provides end-to-end encryption for private communications exchanged daily by billions of people around the world. After its publication in 2013, the Signal Protocol was adopted not only by Signal but well beyond. Technical informat...

‘Today we are happy to announce the first step in advancing quantum resistance for the Signal Protocol: an upgrade to the X3DH specification which we are calling PQXDH. With this upgrade, we are adding a layer of protection against the threat of a quantum computer being built in the future that is powerful enough to break current encryption standards.’

  • boo oneEnglish
    5•1 year ago

    The essence of our protocol upgrade from X3DH to PQXDH is to compute a shared secret, data known only to the parties involved in a private communication session, using both the elliptic curve key agreement protocol X25519 and the post-quantum key encapsulation mechanism CRYSTALS-Kyber. We then combine these two shared secrets together so that any attacker must break both X25519 and CRYSTALS-Kyber to compute the same shared secret.

    Not an expert, but what i read here is that they will be using 2 locks. e.g. one traditional key based lock and another fingerprint based lock, and when you need to open the door, you need to open both the locks.

    • @[email protected]English
      3•1 year ago

      But does that actually give decent protection against quantum decryption?
      I don’t actually expect you to answer that question, it’s pretty pertinent though.

      • ᗪᗩᗰᑎEnglish
        6•1 year ago

        From https://signal.org/docs/specifications/pqxdh/#passive-quantum-adversaries

        PQXDH is designed to prevent “harvest now, decrypt later” attacks by adversaries with access to a quantum computer capable of computing discrete logarithms in curve.

        Also:

        PQXDH is not designed to provide protection against active quantum attackers.

        Basically this makes it pointless to collect any data now with the intent to decrypt it in the future - e.g. the NSA collecting all your encrypted messages to decrypt them all in 5-10 years once they have a capable quantum computer.

        It does not protect against an active quantum attacker - of which there are currently none, so work in the field is likely expected to continue.

        • @[email protected]English
          1•1 year ago

          OK, cool, thanks for the disambiguation. So kinda actual protection, but at the same time lip service. I’ll take that.

          • LollerCorleoneOP
            2•1 year ago

            Also remember that this is only a layer of added protection. Work on this will continue. But this is more than what any other player in this market space currently offers.