Thursday, May 26, 2022

Ep. 4 – Ideal World vs. Real World, Quantum Cryptography & The Lorenz Cipher | Ask the Professor

so someone's asked about what is the difference between the ideal world in the real world well these are terms we use in multi-party computation to actually establish security so what we kind of imagined is that there's this ideal world which computes the function for us without revealing any of the data .

So imagine we've got some godlike figure who actually computes what we want for us now in MPC which is the real world what we try to do is come up with a protocol which emulates the ideal world so someone asked whether quantum key distribution otherwise known as Crompton cryptography will replace classical cryptography in my view it never will .

Quantum key distribution is a very very niche market a very niche area that doesn't really deploy to what the type of systems that we actually use in cryptography at the moment cryptography is a very wide subject it allows us to authenticate data it allows us to communicate between people who have never met before it allows us to engage .

In complicated protocols like electronic auctions electronic voting systems attestation of devices etc none of these issues are dealt with by quantum key distribution it just solves a very very small part of the puzzle so in some sense quantum key distribution is only ever going to be a tiny tiny part if any part of the .

Cryptographic ecosystem someone has asked about was enigma the only cipher used by the Germans actually it wasn't there was a much more important cipher used called Lorentz which was to communicate between the German High Command and the Divisional Commanders out in the field so for example there might have been a single radio signal .

That went from Berlin to Paris to send instructions backwards and forwards from the French command to Berlin and this was encrypted using the Rennes which was a far more complicated encryption algorithm than the Enigma machine the British cracked Lorentz and in doing so they actually brought in the modern digital age because to do so they had to .

Build the world's first digital programmable computer called Colossus which was a huge machine which enabled people to break the Lorenz cipher the successive Lorentz was such that the allies could work out that they're faint of pretending to invade the particle in region had been completely swallowed by the Germans and therefore the Normandy .

Landings could proceed with these facing much less resistance than they would have otherwise have expected and this was because we knew this was going to happen because Lorentz had been broken a few months before the Normandy landings


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