Encryption
Encryption is a security measure used to try to prevent unauthorised access to data during transmission from one system or network to another.
Encryption is designed to scramble data so that if an unauthorised person or organisation manage to steal data packets, they will be unable to understand the content.
In computing, encryption:
- makes use of algorithms to create simple keys that can encrypt data
- keeps the simple key secure by using public and private keys during transmission of data
- only the correct combination of public and private key will allow access to the simple key
- the simple key is then used again to decrypt the data
Development of encryption
The concept of encryption dates from before computers. It has roots in cryptography - the process of scrambling a message using a secret simple key.
If someone wanted to send the message, 'Hello' but did not want anyone who might intercept the message to be able to understand it, they could create a 'simple key'. The simple key is only known by the sender and receiver.
A commonly used example of a simple key from early cryptography is the 'Caeser Cipher'.
When using the Caeser Cipher, the simple key is 'move 3' which means each letter in the original message is replaced with the letter that comes three places after it in the alphabet.
'Hello' would be sent as 'Khoor' because each letter moves three places:
- H → I → J → K
- e → f → g → h
- l → m → n → o
- l → m → n → o
- o → p → q → r
To decrypt the message the receiver would reverse the simple key. They would move three places back from each letter so that ‘Khoor’ could be unscrambled back to 'Hello'.
- K → J → I → H
- h → g → f → e
- o → n → m → l
- o → n → m → l
- r → q → p → o
Simple cryptography like the Caeser Cipher would not provide adequate security when sending data on networks.
For this reason, programmers create more complex algorithms to create simple keys. They add another layer of protection by only transferring simple keys using public and private keys. When a message is received, the public key used to send the data must be recognised as the key that corresponds to the private key used to receive the data.
