Comment by nmadden

Comment by nmadden 10 months ago

4 replies

Just want to point out that the article specifically says to use an authenticated KEM (AKEM). A normal, unauthenticated KEM would not work as it provides no authentication. There are no post-quantum authenticated KEMs as yet.

namibj 10 months ago

There are post quantum KEMs though that authenticate with a classical mechanism, which limits quantum attacks to interactive from the previous total breakage of recorded ciphertext exchanges (e.g. Wireshark capture at a router encountered in both directions of the traffic flow).

  • nmadden 10 months ago

    Are there? I’ve advocated for such constructions in the past, but I’ve never seen an actual proposal. Do you have a link?

    • namibj 9 months ago

      Google's post-quantum TLS experiments that were done in public via Android Chrome are such; basically you just do normal TLS handshake but stack the key derivation from the traditional DH-type perfect-forward-secrecy exchange with a post-quantum-perfect-forward-secrecy exchange that you all seal under the same handshake authentication, and where you make sure to only use post quantum symmetric primitives to fuse the traditional session key material with the PQ session key material such that you don't rely on either one's resistance to keep your secrets secret.

      Sorry I don't have a link quite on hand right now.

      • nmadden 9 months ago

        OK, sure. As far as I’m aware, nobody’s actually made that into an actual AKEM proposal though. (I wish they would, as I think many applications would be fine with pre-quantum authentication and post-quantum confidentiality).