NationStates Jolt Archive


Quantum Encryption Perfected In Warmaster

The Warmaster
01-04-2005, 23:17
WARNING: QUANTUM PHYSICS AHEAD. READ ALL OF IT, NO MATTER HOW BORING OR CONFUSING IT IS.

Holy Empire of the Warmaster
National News Broadcast
WBSN Radio/Television Tower

Quantum theory has existed for centuries. It is the theory that deals with the behavior of objects at the microscopic level. Classical physics, the realm of the visible, can explain the trajectory of a cannonball, but scientists must resort to quantum physics to explain the trajectory of an electron. With recent advances in quantum theory, it has been proved that the world’s most powerful existing ciphers can be shattered by a “quantum computer”, a computer that utilizes quantum theory to process information infinitely quicker than the most advanced modern supercomputer.
The most secure cipher in the world, PGP (Pretty Good Privacy), invented by Phil Zimmerman in 1991, relies essentially on the fact that it is much easier to multiply two numbers than to factor them. Thus, by generating two prime numbers, preferably with hundreds of digits, and multiplying them, one can encrypt a message that would take billions of years to decrypt. However, the blinding speed of a quantum computer could render secure communication a thing of the past. Right now, it is physically impossible to construct a working machine to house the quantum programming. The physics are very complicated, but basically this is because either the photons within the machine must occupy all possible states of existence or be in more than one universe at once. Needless to say, this is believed to be far beyond human engineering talents at this time.
But word has reached the Sacred Emperor that several nations with an interest in information supremacy desire nothing more than to invade the computers of their enemies. The information supremacy of any one nation is a terrible threat to free societies in the increasingly digitalized world of today. As a preemptive defense against such an assault, the Emperor had the head of the Imperial Quantum Physics Research Department unveil quantum cryptography to the masses.
Quantum cryptography is unbreakable by any machine, even a quantum computer. It, very much simplified, is based on several things. One, the best, and as far as I know only way to measure photons (particles of light) is through a filter known as a Polaroid. Second, the one-time or one-use pad, the cipher that quantum encryption uses, is mathematically unbreakable, if it is completely random, which is far more possible with photons than with letters.
Photons, let us assume, spin only four different ways: right, left, up and down. To filter the photons you want to send, you place a + shaped filter to allow horizontal and vertical photons to pass, and for diagonal photons you use an x shaped filter. Let us suppose that in the + filter, horizontal photons are enciphered as 1, and vertical ones are enciphered as 0. In the x filter, diagonally rising to the right is 1, and diagonally rising to the left is 0. So, if you want to send 1101101001 in binary, the transmission would be vertical, right diagonal, horizontal, right diagonal, right diagonal, left diagonal, vertical, horizontal, left diagonal, and right diagonal. You see, the user has a random choice of which filter to use to encipher binary 1: x or +. An eavesdropper cannot pick the right sequence of filters merely by guessing, and so will be wrong half the time. If an eavesdropper uses the wrong filter, he will misinterpret the digit. Further, the sender and the receiver can agree on the right sequence on a normal unsecured phone line in perfect secrecy in three steps.
1. The sender, Jack, transmits a random series of 1's and 0's using a random choice of + and x filter schemes.
2. The receiver, Sarah, has to measure the polarization of these photons. She does not know what filter scheme Jack has used and so guesses. Like an eavesdropper, she is wrong an average of half the time.
3. Now, Jack has sent a series of 1's and 0's and Sarah has detected some correctly, some incorrectly. To clarify things, Jack then calls Sarah on a normal unsecured phone line and tells Sarah the filter scheme he used but not how he used it. For example, he says he used the + scheme, but not whether it was horizontal or vertical. Sarah tells Jack on which occasions she guessed the right filter scheme. Discarding the ones she got wrong, they now share a shorter series of 1's and 0's, without tipping off the eavesdropper.
It is still random, because the first transmission was random and the times Sarah used the right filter are random. The random sequence becomes the key to a one-time pad, which is completely unbreakable, due to the fact that a truly random cipher cannot be deciphered accurately. It will yield the correct answer, yes, but every other possible answer as well. ATTACKTHEVALLEYATDAWN, the correct message, will appear, but every possible combination of letters in that amount of spaces will appear, for example, HKLKHSTRADSEFIFDSIBUC, or DEFENDTHE HILLATSUNSET. It is impossible to distinguish between the possible messages.
Even better, since Jack and Sarah can determine what the correct sequence of photons should be, eavesdropping is impossible. Interfering in any way with the protons will cause them to behave differently than they should, tipping off the sender when the receiver tells them they have received an extremely confusing message.
The Emperor’s encryption plan calls for every digital communication to be encrypted with quantum cryptography. All computers holding sensitive documents such as the personal computers of the Emperor’s staff or the High Command will have their internal code encrypted, to prevent invasion completely. A lockdown system will be installed, so that technicians in the Center for Digital Communication will be able to seal off an infected computer, preventing a foreign program or intelligence from spreading.
In the words of the Emperor, “My friends, when this is finished, the evolution of cryptography will end. Our country shall be utterly immune to any sort of electronic assault. Consider this, my loyal subjects, a new Wonder of the World: a massive, invisible wall of light. We can now sit back and grin, saying to the world, we are finished. We have gathered, we have sown, and now we reap. It is finished, and we are invulnerable at last.”