Today the largest ever prime number was discovered.  It has some 17-million digits, far too many for this humble blog to list, and some would say a complete irrelevance.  But prime numbers, those only divisible by 1 and themselves, play a vital role in the internet.  Why is that?

Prime numbers play a key role in encrypting data to be sent across the internet and other networks, as well as in secure data storage.  Without the number prime, we wouldn’t be able to make our client’s precious data secure.  It does this using a fascinating trick of the primes themselves.

When data is encrypted to be transmitted, a key is generated based on the multiplication of two prime numbers.  The website knows these numbers, and the receiving end also knows these two numbers, but no-one else does.  So the data makes no sense if intercepted, and it is totally secure because of a cool trick of the primes. When you multiple two primes together, is it virtually impossible to reverse the action – you cannot work out the two source numbers from the original number.  And these numbers are massive – typically 1,000 digits long.

The number of digits used is reflected on the number of “bits” used in encryption: 64bit, 128bt, 256bit and so on.  So the more bits, longer the key is and therefore the more secure your data transmission is.

All of this goes on behind the scenes, but is the power behind the cherished padlock icon we have come to love.

By Colin Harris
Sources: http://www.guardian.co.uk/science/alexs-adventures-in-numberland/2013/feb/06/largest-prime-number-17-million-digits
http://www.bbc.co.uk/news/magazine-14305667