Alice wants to send Bob a message.
Thursday, 11 March 2010 10:21
So I've had a very long day. I didn't really get any work done on my Kuala Lumpur piece, but I have made considerable progress in other aspects of my life that had been getting neglected. (IE: Housework!)
I'm on my way to bed, but there's something I've been thinking about that I want to put out there to my lovely viewers in hope I get some insight.
The topic is quantum crytpography.
A brief overview: Quantum cryptography relies on the principals of quantum mechanics to secure data using the transmission of photons through polarized filters to the other end where they are received and decoded with the use of corresponding filters. Based on the alignment of the photons they can be assigned a 1 or a 0 producing binary data.
Alice would start sending Bob a set of photons randomly polarized rectilinearly. Bob would use a randomly assigned set of filters to decode the message keeping the photons that matched and discarding the photons that didn't match to create a key.
Now let's say Chuck wants to eavesdrop to figure out what this key is. Chuck can't start listening in without intercepting some of the photons which, in turn, alerts Alice and Bob to an eavesdropper therefor letting them create a new key.
My question is this: How much knowledge of said eavesdropper are you given? By intercepting and changing the stream of photons one would naturally be aware of their existence, but is the way in which they interrupt measurable? The anomalies are detectable, yes, but do they leave a trail back to the eavesdropper? Would the data leave behind any fingerprints, so to speak, of who or where the eavesdropper is?
I'm off to bed!
(Left to my own devices this is the kind of shit I think about that keeps me up nights.)