You don’t want to take on this man in the rink:

And you don’t want to take on his namesake in the scientific realm.

In my last post I wrote about the Kish Cypher protocol, and was wondering about its potential to supplant Quantum Cryptography.

The very same same day, as if custom ordered, this fighter’s namesake, no other than Charles Bennett himself, published this pre-print paper (h/t Alessandro F.).

It is not kind on the Kish Cipher protocol, and that’s putting it mildly.  To quote from the abstract (emphasis mine):

We point out that arguments for the security of Kish’s noise-based cryptographic protocol have relied on an unphysical no-wave limit, which if taken seriously would prevent any correlation from developing between the users. We introduce a noiseless version of the protocol, also having illusory security in the no-wave limit, to show that noise and thermodynamics play no essential role. Then we prove generally that classical electromagnetic protocols cannot establish a secret key between two parties separated by a spacetime region perfectly monitored by an eavesdropper. We note that the original protocol of Kish is vulnerable to passive time-correlation attacks even in the quasi-static limit.

Ouch.

The ref’s counting …