The Secret Behind Encryption

Symmetry-based encryption involves a secret code that computers communicating with each other use before sending information. For example, if the key is a transposition cipher, where each letter is replaced by a letter five letters down in the alphabet, the computers would both need to know the key to decode the information being sent. Systems using symmetric encryption usually have a new code for each session and discard each code once the session is over.

How public key encryption works.

Public key encryption uses a combination of a public key and a private key. The public key is sent out by your computer to other computers that are authorized to communicate with it, while the private key is only known by your computer. To decode a message, the computer must use both the public and private key. When these types of systems are used on a large scale, digital certificates are used for additional security and a certificate authority must attest that the web server is trustworthy.

But the codes themselves must be hard to crack to keep information secure. Currently, complex algorithms are used as keys and use the factors of 128 bit numbers, which means that the number of possible keys are 2 to the power of 128! This makes them almost impossible to crack, even by the most powerful computers, since it is virtually like looking for a specific grain of sand on a beach...

In the future, however, encryption may take a completely different form. Quantum computers, which essentially use quantum properties to process many things at the same time rather than one after another, have already been built. Although it is difficult for the computers we use today to crack 128 bit encryption, for a quantum computer it would not be difficult. Scientists are already looking at quantum cryptography as a way to provide a more secure way of protecting data and in 2004, it was announced that this method was used to transfer money between Vienna City Hall and an Austrian bank. Quantum cryptography is complicated to explain, but also makes use of quantum states and entanglement: the benefit is that if someone tries to intercept the code, it leaves a trace and destroys the information.

Will this mean that credit card fraud will become history? I guess we must hope that there won't also be any quantum hackers. If they can inhabit quantum states and be in more than one place at once, they will be almost impossible to catch...

For more information:

Howstuffworks - How Encryption Works
http://computer.howstuffworks.com/encryption.htm

Guardian Unlimited - Second Sight
http://technology.guardian.co.uk/online/comment/story/0,,1439237,00.html