Types of Authentication Protocol and How They Work

Maintaining a secure network ensures all of the data you have stored within your network stays private. Secure networks are important to protect yourself, your employees, and your clients. Even if you don’t deal with incredibly sensitive information, it’s important to invest in network security. A data breach of simple usernames and passwords could be very costly and devastating for users. 

Authentication protocols are a layer of network security that help ensure that users on your network are who they say they are, and they help keep data secure. They provide an invaluable way to increase security, and there are many different types of authentication protocols you can choose for your network. 

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What is Authentication Protocol? 

Whenever anybody attempts to access your network, it’s important to ensure they are authorized users and are who they say they are. An authentication protocol is one way you can accomplish this. By having a system or systems in place to authenticate users, you can cut down on hacking and data theft to help keep your information secure. 

While there are many different types of protocols, in general, they follow a set of rules that help the system identify the identity of the person or device that is trying to access the network. This might be a computer, phone, or individual user, for example. 

What is Authentication Protocol? 

How Does Authentication Protocol Work? 

There are many different types of authentication protocols, and each works a bit differently. In short, the receiving party, which is usually a server, verifies the identity of the other party, which is usually a person trying to access the system. Different protocols work better for different use cases and for different levels of security. 

Let’s take a look at some of the different authentication protocols and how they work. 

Password Authentication Protocol (PAP)

Password authentication protocol is one of the most basic and least secure forms of authentication protocol. It’s not encrypted, however, it is simple and easy to implement. With PAP, users submit a username and password into the system. Their credentials are then compared to a database to determine if they are correct. If the credentials are correct, they are authenticated. 

Challenge Handshake Authentication Protocol (CHAP)

Challenge handshake authentication protocol uses strong encryption, which makes it more secure than PAP. It uses a three-way exchange to authenticate users in the system. CHAP also works on an ongoing basis, rather than simply verifying users one time when they first attempt to access the system. This ongoing authentication adds to security. 

Here’s how the process works: first, a challenge is sent to the remote host. Then, the remote host responds with a hash function. The response hash value is then compared to what is expected. If it matches, then they are authenticated and a “handshake” is formed. 

Extensible Authentication Protocol (EAP)

Extensible authentication protocol is often used for wireless networks, point to point connections, smart cards, and more. It’s encrypted, making it a rather secure authentication protocol. 

In EAP, the server first sends a message to the client that the client then computes. The client then sends the results of the computation back to the server. This process can be repeated if the server needs more information. Once the information is verified, the authentication is complete. EAP can also happen multiple times during a session for a more secure protocol. 


Kerberos authentication protocol is often used for Windows systems. It works via secret key cryptography. It’s a common protocol to use, partly because a free version of the protocol is available via the Massachusetts Institute of Technology (MIT). 

Kerberos works when a client first requests an authentication ticket from the centralized key distribution center. Then, the key distribution center sends back an encrypted authentication ticket along with a session key. Next, the client will request access. This triggers an authentication ticket request at the key distribution center. The key distribution center then sends the ticket along with a session key. Then, the server authenticates the client after receiving the ticket. Finally, the server gives the client another authenticator and the authentication is complete. 

Lightweight Directory Access Protocol (LDAP) 

Lightweight directory access protocol is an open, vendor-neutral application protocol. It allows people to access organizations, individuals, and resources on public internet or intranet. When companies store information such as usernames, passwords, and other data, that information can then be accessed through LDAP. 

LDAP works rather simply. First, the user requests information stored in the database and provides credentials. If the credentials are authenticated, they are given access to the information they requested. 


OAuth2 is a popular authentication protocol for authenticating logins on third-party sites. For example, OAuth2 allows you to log in to Pinterest via Google. It’s an ideal authentication protocol because it provides limited access and doesn’t require shared credentials. 

Here’s how OAuth2 works: first, the application requests access for the user. Then, the user approves the request and the application gets an authorization grant. Next, the application requests an access token, and if the token is valid, you are granted access. 

Which Authentication Protocol is Best? 

Of course, no authentication protocol is going to be foolproof. There have been many examples over the years of data hacking and theft. For example, in 2017, Deloitte exposed client emails in a data breach, and in 2020, OAuth tokens were stolen from GitHub. Just because data breaches can happen, however, doesn’t mean you should give up on trying to prevent them. 

While some authentication protocols are more popular than others, there isn’t necessarily one best authentication protocol. Each has its place for specific applications and use cases. Within most networks, you’ll likely use various authentication protocols for various purposes. 

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