Our world runs on random numbers and without them a surprising proportion of modern life would break down. So, why are they so hard to find?

Randomness

There are some things that computers, for all their prowess, don’t do well – and one of them is randomness. Sure, computers spit out data all the time, why not random numbers? The problem is that computers rely on internal mechanisms that are at some level predictable, meaning the outputs of computer algorithms eventually become predictable, too, which is not what you want if you’re running a casino. The same issue can cause headaches for cryptographers. When you encrypt information, you want the keys to the code to be as random as possible, so that no-one can work out how you garbled the original text since that could allow them to read the secret message.

People have long sought external sources of randomness as the basis of random number generators. In this search for true randomness, they have looked practically everywhere for chaotic phenomena that can’t be predicted or manipulated. They have listened to the racket of electrical storms, captured pictures of raindrops on glass, and played with the tiniest particles in the known Universe. The search is far from over.

If you never enter the lottery or have no intention of taking part in a clinical trial, you might think that random numbers don’t really matter to you. But you’d be wrong.

So, how do they work?

Every time you choose a new password, even one you think of yourself, a computer adds another chunk of data to it. This scrambles the password for storage meaning that, if someone hacks a database and steals your password, they can’t easily unscramble it and use it to access your account. That chunk of data added to the password is called a salt and it is derived from a random number.

“We’re using them every day without really knowing,” says Alan Woodward, a computer security expert at the University of Surrey.

Random numbers are essential for securing information, he points out, since they are used whenever a computer encrypts data so that it looks to any casual observer like mere gobbledegook. When you visit a website that begins “https://”, for example, you’re asking your computer and the server that stores the website to, among other things, generate some random numbers, exchange them and then use them to encrypt the data sent back and forth as you load the website and go on to use it. (This is an enormous simplification of the exchange that takes place in just a few milliseconds, but you get the drift.)

When sensitive data is flying around computer networks, especially those accessible by the public, it’s essential to secure that information. Cloudflare, a tech firm that provides cloud security services, uses a lot of random numbers at its data centres. The company has sought some eye-catching ways of generating randomness – including a collection of lava lamps.

Source: BBC

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