How encryption works

Internet security is an important topic to address for anyone who surfs the web. Many of us want to be sure that our private data is being handled securely. The most popular way to protect our data online is through encryption. Encryption of data simply means that the information is encoded so that it can only be read by a key used to decode it. It sounds like super spy stuff, and in a way it is (that is a German enigma machine pictured above). In this article, we will discuss some of the ways that encryption is used to protect our data on the internet.

Computer encryption is based on cryptography, the practice and study of techniques to secure information. If you have ever heard of the Caesar cipher, that is a form of encryption. In our modern era, computers are generating complex algorithms that are used as the ciphers that crack the code.

There are two main modes of encryption: symmetric key and public key.

Symmetric key encryption

Caesar_Cipher
Caesar Cipher by prize Lerthirunvibul

The Caesar cipher is a great example of this. A letter is written to a friend, but all the words are spelled out by rotating the letter in the alphabet 4 spaces. This makes the letter nonsensical to anyone who intercepts it. But the friend it was written to knows the code (shift 4 spaces) and can therefore decode the letter.

The same happens in computing. Each computer has a secret code. The is a packet of information that is transported between the two computers. Once the transfer is complete the second computer decodes the encrypted packet.

Examples of this type of encryption: Hard drives, Private networks

 

Public key encryption

public key encryption
PublicKeyEncryption by Kalani Hausman

Sometimes this is called asymmetric key encryption. The main difference here is that each party does not have the same code to encrypt the message. Instead this method uses two different keys at once, a public key and a private key. The private key is know only to your computer. While, the public key is given to any computer that may want to communicate with it.

To decode a message a computer must use the public key (provided by the computer that it is communicating with) and it’s own private key.

In the example, Sally wants to send Bill a message. To do that, Sally needs to use Bill’s public key which is available to anyone. When Sally uses the public key it encrypts the message so that no one can read it. The only way that Bill will be able to see the message is when he uses his private key, the one that only he has (and is the only way to decode the encryption).

The message is available to anyone because all you need is the public key to pick it up. But, you won’t be able to read that message without a private key. The keys are a long string of numbers, and since they are based only on prime numbers, it makes this system very secure.

Examples of this type of encryption: Digital banking, Secure websites(https, SSL)

Photo Caesar Cipher by prize Lerthirunvibul

Photo PublicKeyEncryption by Kalani Hausman

Photo: WW2 Encryption: Enigma German Machine – cover off by Anthony Catalano [Creative Commons Attribution-NonCommercial-NoDerivs]

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About the author: Astrid Countee

Astrid Countee
Astrid is an Anthropologist, Data Analyst and Software Engineer who has always felt like a writer. She enjoys telling stories about science and technology and their effect on humanity. When she is not writing, she can be found reading and curled up with a cup of tea.

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