Symmetric Encryption: Types & Advantages

Instructor: David Gloag

David has over 40 years of industry experience in software development and information technology and a bachelor of computer science

In today's world, where many aspects of our lives are public, encryption is behind the scenes protecting us. In this lesson, we'll take a look at a specific method, symmetric encryption. At the end of the lesson, you should have a good understanding of this useful technology.

Our Social Nature

These days, we live more and more of our lives in the public eye. Social websites like Facebook, YouTube, and Twitter place personal detail front and center. And why not? Most of us are happy to tell the world of our adventures, even if they aren't that significant. But haven't you ever wondered why more accounts don't get broken into? We hear about that occasionally. Fortunately, it's nowhere near as frequent as it might be. It's like an invisible shield protects us from prying eyes.

What is Encryption?

Encryption is a conversion process that is part of the invisible protection. It takes information in one form (usually human-readable), and converts it to another form (not usually human-readable). Mathematically based, it makes use of an external piece of information, known as a key, to perform this conversion. There are several different types of encryption, and they are used in many places. Some are quite common. As an example, for the personal information stored on your favorite social website like Facebook, or login information for web-access to your bank card. In each case, encryption is behind the scenes doing its thing.

What is Symmetric Encryption?

Symmetric encryption uses the same key to encrypt and decrypt. This means that if you are sending information encrypted with a specific key to someone, they must have that same key to decrypt. For this reason, this method is normally used in localized situations. In the examples above, the key (password) needs to be known by only one person - you. Notable instances of this method include the Data Encryption Standard (DES), and the Advanced Encryption Standard (AES).

What Types of Symmetric Encryption Exist?

There are two basic types of symmetric encryption. The first is stream. It encrypts a message one character (digit) at a time, and sends it as it goes, hence the name stream. Many versions were available before 2005, but you don't see it much these days as most have been broken. A notable example of this encryption is RC 4. The second is block. This method breaks a message up into known sized pieces, and encrypts each piece before sending. DES and AES, mentioned above, are examples of this type of encryption.

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