Let’s touch base with encryption before we dive into what a public key and a private key are.

Encryption is the process of keeping information safe by converting it into a secret code. With the increasing threat posed by hackers and other cybercriminals, encryption has become a necessity. When an authorized person receives data, he or she would need a public or private key or both to make sense of or decrypt it.

Now, how is the encryption process relevant? Well, public and private keys are used to encrypt (convert information into a scrambled secret code) and decrypt data (turn it back to its original and readable format).

Several people in an online directory can access a public key. In contrast, only the data owner and the people he or she shares it with will have access to a private key. The form of encryption one uses depends on the type of key he or she uses. The two forms of encryption are public key encryption and private key encryption. Let’s find out more about them in the succeeding sections.


What Is Public Key Encryption?

Public key encryption is an asymmetric form of encryption since it uses two different keys to encrypt and decrypt data. It uses a public key to encrypt information, and the intended recipient needs a private key to decrypt it. The public key is available to several people, while only the authorized recipient has access to the private key.

How Does Public Key Encryption Work?

The public and private keys in public key encryption are mathematically related. That means the information encrypted using a public key can only be decrypted with a corresponding private key.

When you buy an item from Amazon, for example, you use Secure Sockets Layer (SSL) to encrypt your web session. That way, hackers won’t be able to read sensitive data such as credit card details or PayPal information. When you start the web session, your browser sends information to Amazon’s server using a public key. From that point onward, every piece of data transmitted gets encrypted. Now, for Amazon to read what you sent, it needs to decrypt the data you sent using a corresponding private key.

Watch this video and learn more about public key encryption.

When Is Public Key Encryption Applied?

There are three primary applications of public key cryptography. These are:

Verifying Digital Signatures

Organizations use digital signatures (proof of a message’s, software’s, or digital document’s validity and authenticity) for their communications. Creating a digital signature requires the use of public key encryption in that the sender digitally signs a message, for instance, using his or her private key. The recipient then uses a public key to decrypt and read the message.

Securing Communications

Public key cryptography is normally used to ensure digital content confidentiality. In this scenario, the sender locks the data with his or her public key. And only the one (the intended recipient) with the correct private key can open it.

Enabling Password-Authenticated Key Agreements

A password-authenticated key agreement is an interactive way for two or more parties to create cryptographic keys based on one or more parties’ passwords. Say a person wants to pass on a secret message to another. Person A gets Person B’s password, encrypts it, and uses it as a private key. That way, when Person A sends the message encrypted with that key, only Person B can open it because he or she knows the password.

What Is Private Key Encryption?

Private key encryption is a form of encryption that uses only one private key to encrypt and decrypt data. As such, it falls under the symmetric encryption category.

How Does Private Key Encryption Work?

Remember that private keys are only available to data owners and the people they share them with. As such, when you send a file encrypted with a private key to a colleague, you need to give him or her the private key to decrypt it, too.

Public Key and Private Key Differences

The table below shows the five significant public and private key differences.

public and private key


Whether you use a public or private key for encryption, the most important thing is that you are protecting your files, emails, and web sessions. Both forms of encryption do not stop hackers from intercepting data but render it unusable and unreadable unless they also get hold of the private key.

Private Key Encryption Is Safer than Public Key Encryption.
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