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Comment Kilimanjaro (Score 3, Funny) 28

by etnoy (#64847691) Attached to: Spacecraft Launches Toward Asteroid Knocked Off Course By NASA
Sir: Now let me fill you in. I'm leading this expedition and we're going to climb both peaks of Mount Kilimanjaro. Bob: I thought there was only one peak, sir. Sir: Well, that'll save a bit of time. Well done. Now the object of this expedition is to see if we can find any traces of last year's expedition. Bob: Last year's expedition? Sir: Yes, my brother was leading that, they were going to build a bridge between the two peaks. My idea I'm afraid.

Comment Re:Submitter has no clue what QC is. (Score 1) 101

by etnoy (#51160939) Attached to: Swedish Researchers Break 'Unbreakable' Quantum Cryptography

Semantics. QKD is a way of obtaining a secure key which we then use to perform one-time pad encryption. In other words, we use it for encrypting information.

I don't understand this. Sending a one-time pad key is equivalent to sending the plaintext, as far as information transfer goes. (Otherwise, it isn't a real one-time pad.) The only advantage of the 1TP is that we can send the pad when we can get a secure communications channel, and then send messages at arbitrary times over insecure channels. If you have a reliable and persistent secure channel, why bother with the 1TP key?

Excellent question! QKD is just what it means, key distribution. There is actually no transmission between sender and receiver, instead it randomly establishes a secret, shared key at Alice's and Bob's place. Therefore, to do transmission, you use OTP to perform encryption.

Comment Re:Move along, nothing new here (Score 1) 101

by etnoy (#51149341) Attached to: Swedish Researchers Break 'Unbreakable' Quantum Cryptography
Makarov's group attacked the E91 protocol, our paper attacks the Franson system. A significant difference is that we show the Franson system to be insecure even if the device is implemented with perfect devices. Makarovs papers are very well-written and interesting to read. I recommend starting to watch one of his YouTube lectures: https://ancillary-proxy.atarimworker.io?url=https%3A%2F%2Fwww.youtube.com%2Fwatch%3F... , it is entertaining, highly interesting and is on a reasonable level for the average ./ reader.

Comment Re:Submitter has no clue what QC is. (Score 1) 101

by etnoy (#51149327) Attached to: Swedish Researchers Break 'Unbreakable' Quantum Cryptography
It's hard to argue about QKD without understanding how it works. Your starting point about QKD transmitting keys in the clear is wrong, as the information does not even exist in the quantum channel. Alice's and Bob's measurement operations are what create the secret key. That key is then used in a one-time pad. Also, OTP is exactly what we use after finishing a QKD session. The key requirements you talk about is exactly what makes OTP 100% secure.

Comment Re: Submitter has no clue what QC is. (Score 1) 101

by etnoy (#51149309) Attached to: Swedish Researchers Break 'Unbreakable' Quantum Cryptography
The Franson interferometer is a QKD system that many (including senior researchers in the field!) believe is perfectly secure. Our paper shows it isn't and never will be. Also, there is no "general" QKD system, only a number of protocols, each with a corresponding security proof. The headline is correct.

Comment Re:quantum crypto is not "unbreakable" (Score 1) 101

by etnoy (#51149267) Attached to: Swedish Researchers Break 'Unbreakable' Quantum Cryptography
In the QKD picture, the security proofs place no restriction on the computational power of the attacker, so Diffie-Hellman, IPSec, VPN Tunnels, SSH, SSL/TLS all become broken. The one crypto method that remains safe is the one-time pad. (We call this information-theoretic security). What QKD does is allow Alice and Bob to randomly and secretly generate a key. Therefore, the system is completely safe. In fact, we can prove this mathematically, so the QKD layer is absolute...well, except for the system we just showed to have a flawed security proof ;)

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