What are some differences between a Single photon QKD system (BB84) and an EPR photon-pair QKD system (BBM92) for quantum public key distribution?

  • $\begingroup$ Is there a reason for using "public" in the question? $\endgroup$
    – fgrieu
    Mar 6, 2018 at 10:51
  • $\begingroup$ yes, I was referring to public key cryptography. $\endgroup$
    – Nathan Aw
    Mar 6, 2018 at 11:03
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    $\begingroup$ It is very unusual to combine public key cryptography with quantum cryptography. The main virtue of the later is to replace the unproven mathematical assumptions of the former by laws of quantum physics. $\endgroup$
    – fgrieu
    Mar 6, 2018 at 11:46
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    $\begingroup$ @fgrieu: actually, I would hope that in practical QKD systems, some sort of conventional cryptography (symmetric or asymmetric) is done in addition. QKD systems are still working out their side channel issues (which are much more serious than in conventional cryptography), not to mention the trust issues if you need to relay through multiple QKD links. If you're spending 20K on a QKD link, it'd make sense to spend a comparatively tiny amount on conventional crypto as well... $\endgroup$
    – poncho
    Mar 6, 2018 at 14:23
  • $\begingroup$ @poncho. Agreed. I wish I had written: it is very unusual to distribute the key of a public key cryptography system using quantum cryptography. $\endgroup$
    – fgrieu
    Mar 6, 2018 at 17:56


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