Is it acceptable from a security point of view for an MPC protocol to use non-post quantum cryptographic primitives?

Note that except for secret sharing, which provides information-theoretic security, many primitives are based on computational security.

I am interested in general (system level) and specific (individual primitive level) arguments to answer this question.

  • 1
    $\begingroup$ To me the current direction in MPC protocols seems to be "go as fast as possible with acceptable security" and right now "acceptable security" includes non-post-quantum public key cryptography. But note that quite a few MPC protocols rely mostly on symmetric cryptography and / or trust assumptions and the remaining public-key crypto parts can probably be ported to PQ crypto if needed. $\endgroup$ – SEJPM Jul 15 '20 at 8:59
  • $\begingroup$ Well, do you know anyone with a working large-scale quantum computer? $\endgroup$ – Maeher Jul 15 '20 at 9:42
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    $\begingroup$ Of course it's ok, but very rarely necessary. 99% of modern MPC protocols are built in a modular way from general primitives (e.g. oblivious transfer), which can later be instantiated under the assumptions you like (post-quantum or not). $\endgroup$ – Geoffroy Couteau Jul 15 '20 at 9:52
  • $\begingroup$ Thanks everyone for putting comments. I understand the current direction. I think this can be closed. $\endgroup$ – mallea Jul 16 '20 at 0:53
  • $\begingroup$ I think the question is actually interesting [hence edited]. The comments might be converted into answers if people have the inclination. $\endgroup$ – kodlu Jul 18 '20 at 0:38

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