You're putting in your credit card details to make an online purchase. As you type in your card number, you feel slightly uneasy about sending it into cyberspace.
How often have you wondered whether your personal information is really safe from cyber-theft despite assurances that it is a 'secured connection' and your transaction is 'verified' by so-and-so? To put it in nerdy terms, has your information been encrypted effectively so it will not be understood even if a hacker gains access to it?
Encryption is the science of codifying a message so it will be unintelligible without the code, which usually comprises an algorithm and a key. Only the message's intended recipient, who has been given the algorithm and key, can decipher it.
For its modern mathematical incarnation, we must thank the brilliant British mathematician Alan Turing, whose 100th birthday was commemorated on June 23.
However, encryption is not a new science. One of the earliest recorded encryptions was used by Julius Caesar while he was waging the Gallic Wars (58 to 51BC) across Europe. To communicate with his supporters in Rome, he used a rudimentary encryption that came to be known as the 'Caesar cipher'.
He simply substituted one letter for another a certain number of places down the alphabet. For example, the letter A in the original text would become D in the encrypted text. Hence 'crossing the Rubicon' would become 'furvvlqj wkh uxelfrq'.