WeekEnd Feature:In two minds about it!­

by Ian Thompson, CCSP Staff Editor
Aug 14, 2004

I'm sitting in my chair. In front of me is my keyboard, sitting beside it is the mouse. Forgive this seemingly basic introduction to the immediate layout of my office, but it serves to point out what we know as obvious things can only be in one place at a time. I mean, I cannot be sitting here whilst simultaneously at work marking projects and fixing servers. Sorry, boss! However, this may be because I'm just too damn big read on!­

Physics

For all of us, we live in a physical world where, if I punch a glass window, my hand would pass through it leaving a hole (just shortly before the falling glass would do likewise to my hand, no doubt...). We live a world of certainties like this, otherwise how could we be sure of all those NCAP figures and stats showing which car is safest to have a crash in (quite a few), or would cause least damage to pedestrians and cyclists who get in the way (almost none).

We are also used to newer, faster CPUs from AMD, Intel and so on that follow Moore's Law quite well. Whenever the problems of overheating become a problem, they just handily develop a way of cramming more stuff closer together onto smaller pieces of silicon. I remember buying stuff that boasted the distance of 0.25 I'm between components. Now, given that the latest Pentium CPUs are built on 0.09 I'm ˇ®fabs', which is to say a fabrication plant capable of dealing with gaps of just 90nm, we can see the advances made. Things will get even tinier for the Xbox-2. However, it can't go on indefinitely!­

How low can you go?

You see, as things get smaller and ever smaller, there comes a point at which the normal physical rules with which we're all so familiar just stop working. I'm talking quantum limits here!

­ Quantum physics is a bizarre place to exist. You get terms like superposition, uncertainty and entanglement used by scientists who are rock-solid sure that scissors beat paper, rock beats scissors and paper wins over rock. They are certain of the laws defined by Sir Isaac Newton. They know that light is just a part of a huge electromagnetic spectrum that can be split up and controlled in ways that are repeatable time and again.

So why did Einstein resort to using the term "spooky interaction"? That sounds like things happening that even he could not fathom. Great names have had difficulty understanding quantum physics even Niels Bohr admitted that anyone who could contemplate quantum mechanics without getting dizzy hadn't properly understood it.

As cables get closer together, the gaps become so tiny that quantum effects begin to take over, which mean that standard technology methods of producing CPUs will cease to follow Moore's Law in about 15-20 years. However, that's getting off-topic for this site let's swing back to security!­

Uncrackable?

Hands up all those who use PGPˇ­ One, two, three ­ okay, so that's several million of all online users. PGP is a technology that allows secure encryption of messages whilst also using public key distribution, thus getting around the problem of eavesdroppers stealing the unlock key to private messages. It's secure enough to get its creator into trouble with the US government, under the rules of exporting ordinance not the first time that computing technology has been considered to be as dangerous as a ballistic weapon in the wrong hands. However, it still relies on a mathematical method to encode/decode the plaintext. Here's a piece on the USG's rules.

As can be seen time and again, mathematical methods can be broken. It just takes time. The first programmable computer, created by a UK GPO telephone engineer and used in Station-X, Bletchley Park in the Second World War, was used to break the German Enigma cipher on a daily basis. PGP is several steps above this, though and back in 1997 it was estimated that all 260 million PCs in the world couldn't crack a PGP-encoded message in less than 12 million times the age of the universe. This is a long time in anyone's estimation.

However, this assumes that a brute-force method is used the low-rent approach that tries every available key combination (and PGP has trillions of them). Even the Station-X was able to use mathematicians to spot short-cuts, and a combination of methods (including a brute-force method once the code-breakers had narrowed things down significantly) resulted in a relatively quick unlocking of secret communiques.

The process of mathematically breaking a coded message is called factoring. This involves finding two very large numbers that can be multiplied together to break the cipher. Peter Meyer's "Introduction to the use of encryption" is a good start to finding out a bit more on this subject, as is TheFreeDictionary.com's article, which includes a huge number of cross-references.

Factoring has been successful in the past (a 50-bit key was cracked in 1980, and a 75-bit one in 1984), but equally successful has been to exploit the weaknesses in implementation of security standards, such as the WiFi WEP system, with its unencrypted initialization vector (IV) issue leading to an easy scalp for the serious codebreakers out there. Any foolproof system is open to flaws simply because it's been developed by people.

Quantum computing

Quantum computing relies on those principles of superposition, entanglement and uncertainty that made Niels Bohr's head spin and Einstein resort to Scooby-Doo phrases. It also relies on light, and this is the next key step in computing the optical processor. The light is polarised to carry the data stream, but it's the action of polarising light where the first oddity of quantum physics comes in!

­ Superposition is the ability to be in two places at once. That which my boss wishes I had, and I wish my cash had (you know, spend it but still have it in my wallet ¨C or is that just another definition of a credit card?). When the individual photons are polarised, it is placed in an orientation that we observe as cutting out glare on water, or making our photographs look more like those brochure shots of Greece very blue sky and sea, etc. However, until we observe it, the photon has actually been following both the polarised and unpolarised positions at the same time. This is what make quantum physics difficult to follow that a particle can be aligned and unaligned right up until we see it, whereupon it decides to be just one of these possibilities. Freaky.

You have reached the Quantum Physics support hotline. For a better explanation, please enter the exact answer of 22 divided by 7

Superposition can lead to extremely fast computers. Interesting discussions include"The Quantum Computing Revolution" and other places, including some really neat pictures that demonstrate superposition.

However, moving on to entanglement means that there may indeed be a way of transmitting information instantly and over any distance. Change one sub-atomic particle on Earth, and its entangled partner on Mars immediately reflects this change!­ Beam me up now.

And, even more briefly, the uncertainty of position means that we have to have the correct filter to decode the message, or our incorrect first attempt will actually change the message so that any subsequent attempt will be on a corrupted message. This means that something encoded by quantum cryptography can never be cracked, not ever, no matter what method is used. Until observed, the code remains in superposition after observation, superposition is lost and the coded message is useless. It also means attempts to crack the code are recorded by the code itself.

Right, I need more help on this­ let's see­ 3.1415926535897932384626433832795028841971693993751058209749445923078164062862089986280348253421170679821480865132823066470938446 ­etc.