[14172] in cryptography@c2.net mail archive
Re: quantum hype
daemon@ATHENA.MIT.EDU (starwars)
Sun Sep 14 11:32:53 2003
X-Original-To: cryptography@metzdowd.com
X-Original-To: cryptography@metzdowd.com
From: starwars <nobody@tatooine.homelinux.net>
To: cryptography@metzdowd.com
Date: Sun, 14 Sep 2003 03:32:07 +0200 (CEST)
Martin F Krafft asked:
> So MagiQ and others claim that the technology is theoretically
> unbreakable. How so? If I have 20 bytes of data to send, and someone
> reads the photon stream before the recipient, that someone will have
> access to the 20 bytes before the recipient can look at the 20
> bytes, decide they have been "tampered" with, and alert the sender.
Well, there's a long explanation and a short one, and I don't think
you got the short one yet.
The short version is that you don't send your real data, you send
random bits. Once both sides have agreed that they were received OK and
not eavesdropped on (possible with QC because eavesdropping changes the
data), then you use those random bits as a one time pad, xor them with
your real data, and send that.
This way, if someone does tap the line, all they get is random data,
and their tappage will be discovered.
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