WHAT IS ENCRYPTION?
Encryption is a way of disguising data so that no one can read it unless they know how to reverse the disguise. It is used for keeping information private on the internet, such as emails or bank details.
HOW DOES IT WORK?
Encryption is used to keep important data safe. We can consider how it works by imagining this data as a box containing valuable items.
Suppose I want to send you this box. I could put a lock on it, but I would have the key for that lock and you wouldn’t. Clearly there is no point sending the key with the box. I also cannot send the key separately, as it is not protected. How can I ensure the box reaches you safely?
I put my lock on the box and send it to you. Then you put a second lock on the box, one you have a key for, and send the box back to me. I now remove my lock and send it to you again. This time you can open it, as only your lock is on it. This is one way encryption can work.
You have a lock and a key. You send me your lock, and keep your key. Now I have the lock and you have the key, so I can lock the box and send it to you. This is how public key encryption works: anyone can get ahold of the lock, but only the recipient has the key.
WHAT ARE THESE LOCKS AND KEYS?
The ‘lock’ for an encryption is known as the encryption key, and the ‘key’ is known as the decryption key. The encryption key is used to scramble the data to make it unreadable. The decryption key is used to unscramble this data.
A SIMPLE EXAMPLE KEY
One basic encryption key for sending messages is the Caesar shift. Here, you take each letter from your message and, in the encrypted message, write the letter that comes after it in the alphabet. For example, the word ‘hello’ becomes ‘ifmmp’.
The decryption key for this tells us to take each letter from the encrypted message and replace it with the letter that comes before it in the alphabet. For example, if you received ‘hppeczf’, you could decrypt it to ‘goodbye’.
Today, our encryption keys need to be much more complicated than the Caesar shift. The power of computers means that basic encryptions can be easily unscrambled. This means computer scientists are constantly working to design more elaborate keys. Meanwhile, hackers are constantly working to discover the corresponding decryption keys.