I'm studying the performance of post-quantum KEM in TLS with the OQS (OQS is a project that integrate liboqs to openssl).

I don't know why, but the KEM algorithms performance in TLS is 10 times slower than using the openssl speed command.

For example, Kyber512 takes more or less 2.20 ms to perform the key generation in TLS with the method OQS_KEM_keypair, while with the command openssl takes more or less 0.14 ms in a Raspberry Pi 3B+.

Can someone explain what's wrong? Does the TLS protocol affect in the post-quantum algorithms speed?

  • 1
    $\begingroup$ Because of different sizes? $\endgroup$
    – kelalaka
    Apr 13, 2021 at 22:20
  • $\begingroup$ Yes I thought the same, that the keys size or the message shared size change with the TLS protocol. But I don't understand why. $\endgroup$
    – jmr
    Apr 14, 2021 at 12:58
  • $\begingroup$ It could also be programming overhead, data locality, IO overhead and whatnot, or a combination of many of these. Without explicit knowledge on how this is programmed it will be pretty tricky to establish, unless indeed different key sizes are used. $\endgroup$
    – Maarten Bodewes
    Apr 15, 2021 at 21:36

1 Answer 1


Yes, the TLS protocol can potentially affect the performance of post-quantum algorithms. There are several factors that could potentially affect the performance of these algorithms in TLS, such as the specific implementation of the algorithms, the hardware and software environment in which they are running, and the overhead of the TLS protocol itself.


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