Public Key Encryption: Definition & Example

Instructor: David Gloag

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

Protecting information transfers and e-commerce transactions is of vital importance these days. And with the ever-increasing number, that is sure to continue. In this lesson, we'll take a look at commonly use method, public key encryption, and how it works.

The Protective Barrier

If you are like many people in North America today, you have purchased something online. In fact, if you are like most, you have probably purchased many things online. It is becoming more and more popular every day. But have you ever wondered why criminals haven't attempted to steal the money you used, or at minimum, mess up the transaction? Well, the truth is somebody likely has. You don't hear about it though because there is an invisible barrier that protects you. That barrier is made up of encryption, and one specific type is public key encryption.

What is Encryption?

Encryption is the process of taking information in one form (which can be read by humans), and converting it to another form (which can't usually be read by humans). It is mathematically based, and 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 for various things. Common examples include storing personal information on social websites like Facebook, protecting information passed between your web browser and e-commerce websites like Amazon, and the login credentials stored on your personal computer. In each case, encryption is behind the scenes, working to protect you and your information.

What is Public Key Encryption?

Public key encryption is a form of encryption that uses two keys. A public key, which everyone knows, and a private key, which only you know. To encrypt, the public key is applied to the target information, using a predefined operation (several times), to produce a pseudo-random number. To decrypt, the private key is applied to the pseudo-random number, using a different predefined operation (several times), to get the target information back. The algorithm relies on the fact that encryption is easy, and decryption is hard, making decryption impractical without the key. It was the first system to allow secure information transfer, without a shared key.

What is It Used for?

Public key encryption is used commonly today for securing communications between web browsers, and e-commerce websites. In this scenario, the connection makes use of a Secure Socket Layer (SSL) certificate, which is created from the public and private keys mentioned above. The resulting pseudo-random number forms the basis for the certificate. The most common algorithm used for this encryption process is RSA, named after the researchers that initially proposed it (Rivest, Shamir, and Adleman). It is also the best understood algorithm, as it has been studied for years by a variety of researchers.

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