What are the different types of authentication?

The goal of authentication is to confirm that the person attempting to access a resource is actually who they say they are. 

There are many types of authentication used to achieve this, ranging from traditional passwords to modern approaches like Multi-Factor Authentication (MFA) and Single Sign-On (SSO). 

However, these methods only touch on the problem, without addressing the deeper technical challenges behind it.

In this guide, we’ll provide an overview of the most common types of authentication, along with the most popular protocols, that businesses can use to verify a person’s identity and keep systems secure.

Authentication vs. Authorization: What’s The Difference?

Authentication and authorization work together, but they serve different purposes:

• Authentication validates the identity of a user. 
• Once that is done, authorization verifies their permission level. 

For example, authentication is necessary for a user to enter the company database, but authorization is what decides what information they are allowed to view and change.  

Authentication Protocols vs. Authentication Methods

“Protocols” and “methods” have two different meanings for authentication.

An authentication protocol is an underlying framework that lays out the rules for verification. 

For example, the Password Authentication Protocol (PAP) verifies users by checking a submitted username and password against stored values.

On the contrary, an authentication method is how a user proves their identity. It works on top of a protocol and can include something they know (like a password), something they have (like a one-time code sent to their phone), or something they are (like a fingerprint). 

For example, Two-Factor Authentication (2FA) combines a password with a temporary code by layering security on top of the protocol beneath it. This makes it much harder for attackers to get access with only a stolen password.

With one or more methods of authentication in place, authentication protocols can verify that a user is who they say they are.

Common authentication methods

To protect sensitive systems and data, organizations often implement multiple types of authentication. Because the more privileged the user or sensitive the data, the stronger the authentication should be.

So, let’s look at some common authentication methods: 

Multi-Factor Authentication

MFA requires users to verify their identity using two or more factors from different categories. 

It could be something you know (like a personal question), something you have (like a one-time code or hardware token), or something you are (like a fingerprint or face scan).

This way, after entering a valid username and password, you might be prompted to approve a push notification, enter a one-time code from an app like Authenticator, or verify a code sent to your phone. 

Alternatively, you may be asked to verify a code that was sent to your email, depending on how the authentication method is configured.

This is becoming more common because passwords alone are no longer considered a secure method. 

Why?

Because even strong passwords can be cracked with modern tools. But what’s even worse is that many users unintentionally make it easier by reusing the same password across accounts or choosing weak, guessable ones.

Two-factor authentication 

2FA is a subset of MFA. 

Unlike MFA, 2FA requires exactly two methods of verification, which would mean entering the user’s password in addition to one of the methods mentioned above (e.g., verifying a code sent to their phone, email, or app).

It’s becoming more common with consumer applications because it offers much more security than a password alone, without causing a lot of inconvenience for the user. 

2FA works best when the two verification factors come from different categories, such as something you know (like a password) and something you have, such as a phone (used to receive a one-time code or push notification) or a hardware token like a YubiKey, or something you are, such as a biometric identifier like a fingerprint or facial scan.

Single Sign-On

SSO lets you log in once and gain access to multiple systems without re-entering credentials. 

Rather than signing into each website or application individually, you authenticate through a centralized identity provider, a trusted service that confirms your identity on behalf of connected apps.

Here’s how it works:

• You sign in to this identity provider using a secure protocol like SAML or OAuth. 
• Once authenticated, you can access all participating services automatically. 

Note: You may be prompted to reauthenticate periodically, but as long as your session remains active, the experience feels smooth and uninterrupted.

When an enterprise uses an SSO provider, its employees need to log in only once each day. From there, authentication takes place behind the scenes as the identity provider exchanges verification keys with all of the websites and apps that you have set up to use SSO. 

Can SSO and MFA/2FA Be Used Together?

Yes, and it’s actually the recommended approach. 

With SSO, you only need to remember one strong password, which reduces login fatigue and encourages better password hygiene. 

But adding MFA on top of that introduces another layer of defense, like a push notification or one-time code, making it much harder for attackers to break in with stolen credentials.

Many organizations apply MFA selectively to their most sensitive systems. This way, employees enjoy the convenience of SSO for everyday apps but face additional verification when accessing critical data. 

Security frameworks like HIPAA, PCI-DSS, and GDPR encourage this combination because it strengthens defenses against phishing and credential theft while still keeping the login process user-friendly.Biometric Authentication

Biometric authentication verifies your identity by measuring unique biological characteristics such as fingerprints, facial recognition, iris scans (verifies identity by analyzing the unique patterns in the colored part of the eye), or even voice patterns. 

Because these traits are difficult to replicate, biometrics provide a strong layer of security that goes beyond passwords or tokens.

When you use facial recognition to unlock a phone or access a system, the process is quick and seamless. But in some cases, environmental factors or hardware limitations might cause it to fail, so you would have to use an alternative authentication method. 

Unlike passwords, biometric data cannot be changed if compromised. This is why organizations must encrypt biometric data and tightly control access through strong governance and compliance practices.

Certificate-Based Authentication

Certificate-based authentication uses digital certificates to verify the identity of users, devices, or machines. 

A certificate is a digital file that contains the public key and identity details of the entity it represents. When someone attempts to access a system, the certificate is validated, and access is granted only if the corresponding private key is present by ensuring that the user or device is who they claim to be.

This method is highly secure because it relies on cryptographic techniques, making it difficult for unauthorized users to access the system. 

However, managing digital certificates can be complex because it involves issuing, renewing, and revoking certificates at scale, all while ensuring they remain trusted and up to date. 

This requires a robust Public Key Infrastructure (PKI), which is the system of technologies, policies, and processes that securely manage keys and certificates to enable trusted communication. 

Because of this strong security, certificate-based certificates are particularly helpful in environments where secure communication is critical, such as in banking or government sectors.

Token-Based Authentication

Token-Based Authentication involves using a physical or digital token to verify your identity. 

These tokens can be hardware devices like USB sticks or smart cards, or software-based tokens that generate one-time passcodes (OTPs). 

When logging in, you have to provide your usual credentials and then enter a code generated by the token.

This adds an extra layer of security by ensuring that access is granted only when the user possesses the physical or digital token. While very secure, token-based authentication can be inconvenient if the token is lost, forgotten, or becomes inaccessible. Because then you may require additional steps to regain access.

Token-based authentication is often combined with other types of authentication (like MFA) to strengthen overall access controls, especially for VPNs, remote systems, or privileged user accounts.

Choose the Right Authentication Method for Your Needs

To help you decide which authentication method best suits your needs, here’s a comparison of the most commonly used options:

Authentication Protocols: The Backbone Of Security

Authentication protocols lay out the underlying rules that verify that users are who they say they are. 

The least secure protocol is PAP, which asks a user to enter a password that matches the one saved in the database. It does not use any encryption, which is why it is considered insecure and outdated.

A number of other authentication protocols have been introduced over the years, all with the goal of improving security. 

Let’s look at the most common ones. 

Security Assertion Markup Language

SAML  support SSO by allowing you to log in to an identity provider, which verifies your identity each time you request access to an app or site through a participating service provider. 

SAML was designed to simplify user access to multiple apps without requiring multiple logins. In fact, it still remains the go-to protocol for enterprise SSO, especially in large organizations and B2B environments where legacy systems and a wide range of SaaS applications must be connected securely. 

Open Authentication

OAuth allows apps to grant “secure designated access.” It is one of the most popular authentication protocols on the web. 

Facebook uses OAuth to allow users to grant websites permission to view and post on their timeline without sharing the user’s Facebook password.

OAuth is the go-to protocol for delegated authorization, widely used to secure APIs and enable “sign in with” options in web, mobile, and consumer applications.

OpenID Connect 

Built upon OAuth 2.0, which is an authorization service, OIDC protocol adds a simple identity layer on top of the authorization service, allowing clients/service providers to verify the end user’s identity. 

It is the go-to protocol for authentication in cloud-native, SaaS, and mobile applications, valued for its lightweight JSON-based design and smooth integration with APIs and microservices.

Lightweight Directory Access Protocol

LDAP is best suited for organizations that use Active Directory or other directory services to store user information. AD holds this information as raw data, and LDAP is needed to retrieve it in a usable, structured form—such as user names, groups, and permissions. In practice, LDAP is used as an authentication protocol, since many applications rely on it to validate user credentials against AD or another directory.

WS-Federation

WS-Federation builds on WS-Trust and provides a way for different security realms to share identities. 

It enables you to access applications across organizational boundaries using a single set of credentials. 

While WS-Federation has been largely replaced by SAML and OIDC in modern systems, it is still supported in many Microsoft identity platforms for compatibility.

Kerberos

Kerberos is a network authentication protocol that uses secret-key cryptography and tickets to securely verify user identities. 

It is the default protocol in Windows Active Directory environments and is widely used in enterprise networks for secure, mutual authentication between users and services.

SAML vs. Other Protocols: Which Is Best for Your Business?

With all these authentication protocols, it may be difficult for you to determine which one is best for your needs. However, when it comes to security and reliability, SAML is considered the industry standard. 

Here’s a tabular comparison between SAML with OAuth and OIDC to help you understand why is that so: 

Why SAML Is Ideal for Businesses

For businesses that are interested in adding SSO capability, many are inclined to go down the route of creating a proprietary solution. 

Often, this process begins with good intentions and is typically under the false mindset that a proprietary solution will be the most secure, the most flexible, or even the most cost-effective.

But in reality, proprietary SSO solutions rarely work out as intended. At the enterprise level, implementing a proprietary SSO solution could mean that connecting with each app or software requires a new integration or implementation, which represents major development resources and a lot of unnecessary complexity. 

So, if you are thinking about creating a proprietary authentication platform, think twice. 

Here’s why SAML is a better option: 

• Connect with many partners through one implementation without heavy coding or testing
• Scale reliably to meet the needs of large enterprise environments
• Adapt flexibly with XML and support multiple identity providers if needed
• Integrate seamlessly with SSO and pair with MFA for stronger security and usability
• Rely on a proven standard trusted for secure authentication across industries

Supporting Cybersecurity and Data Governance

You need the right authentication protocol to protect your business. But authentication is only one layer of your security framework. So if you treat it as the whole solution, you leave gaps that attackers can exploit.

Because cyberattacks are becoming more frequent and more sophisticated every day, you can’t only focus on logins and passwords. You have to step back and look at the bigger picture: how cybersecurity connects with data governance.

Why Data Governance Is Important

Data governance is about control. 

You need to know what data you have, where it lives, how sensitive it is, who should access it, and what happens if it goes outside your walls.

When you compare authentication methods—say, SAML vs. MFA—you’re shaping how your organization manages identities, assigns roles, and controls access. In other words, every authentication decision becomes a governance decision.

Why Visibility Should Be Your Priority

If you can’t monitor your data, you can’t protect it. Without transparency, your security team doesn’t know what’s at risk or how to respond.

That’s why monitoring is so important. 

LogicMonitor gives you real-time visibility across your infrastructure. With it, you can strengthen security, enforce access policies, and maintain compliance without adding endless manual work.

The payoff for you? 

Your security team knows what to protect, so operations run smoothly.