If you landed on this blog post, chances are that you care about keeping your API secure. It's an important topic to discuss: API exploits are on the rise, and you don't want unauthorized users accessing your data. A big part of that security is implementing API authentication and API authorization. These API access control measures are a foundational aspect of API security.

But if you're thinking you might not be doing enough to control access to your API, it's not too late to correct course. This article has all the info you need to learn about authentication and authorization, the most popular authentication methods, and get help selecting the best method for you.

Difference between authentication and authorization?

It's easy to confuse API authentication and API authorization. You may know that both help ensure that the right people access the right data, but what's the difference between the two? And why should you care about enforcing both of them?

Here's one way to think of it: imagine your API was a library, and your sensitive data was a rare first-edition book. The API authentication would check each potential borrower's government ID to make sure they're really the person they claim to be. Once their identity was proven to be authentic, the API authorization would check their library card to see if they're allowed to access the section with rare books.

Authentication and authorization work together to keep your API secure. In the previous example, a borrower might have proven their identity, but may not have access to the restricted section from which the rare book came. So authentication may prove successful, but authorization may still prevent borrowing that book. In the same way, you can use authentication and authorization together to make sure the right people access the right data using your API.

What is API authentication?

API authentication verifies that a user is who they claim to be. There are many types of API authentication, and we'll explore a few of them later in this article. But no matter what method you use, you want to make sure that each user (or client application) connecting to your API proves their identity.

What is API authorization?

After you prove the user's identity, you can check which data that user is allowed to access. That process is authorization. Authorization ensures that the user is authorized to view or edit a specific set of data.

The benefits of API authentication

API authentication is critical to the security of your data. By proving a user is who they say they are, you get the following benefits.

Protect against unauthorized access: Proving a user's identity prevents bad actors from pretending to be an authorized user and gaining access to sensitive data they shouldn't see.

Ensure data integrity: Not only can a bad actor with unauthorized access see sensitive data, they can change or drop entire datasets. Even non-malicious users can unintentionally compromise data integrity if you don't authenticate users.

Regulate access control: When you authenticate API users, you don't have to set data permissions for each user individually. You can leverage access control policies to apply rules across groups of users to control who can access which resources.

Improve auditability: It's much easier to determine who has accessed your data and when if you use API authentication. Audit logs can help with debugging in case of issues, tracking suspicious activity, and compliance with security standards (if applicable to your organization).

Simplify integrations: Many products with which your API can integrate require authentication. Collecting this information when they connect to your API makes it easier to connect to the integration without supplying additional information.

Most Used API Authentication Methods

So API authentication is critical, but how can you start implementing it?

The first step is choosing an authentication method. There are multiple authentication methods available, and different methods are appropriate for different situations. Understanding the differences can help you select the best method for you. Here are four of the most popular API authentication methods used to secure the APIs of countless organizations.

Basic authentication

Basic HTTP authentication is the simplest method of API authentication. It involves adding a username and password to the request in every API call.

Pros of basic authentication

• It's lightweight and easy to implement. Basic authentication doesn't require cookies or a login page; you can implement it right in the HTTP header.

Cons of basic authentication

• It's vulnerable to security breaches. While this method is easy to implement, it's not very secure. The username and password are encoded with Base64, but they aren't encrypted and can easily be decoded by a third party. Once decoded, the third party has a valid username and password that can be used to access your API. Additionally, there is no protection against brute-force password attacks, which can also result in unauthorized access. And of course, some users will choose weak passwords that can be easily guessed.
• Users can't easily reset their password. If a user forgets their password, there's no option to reset it easily in basic authentication, which can be an administrative headache for your organization.

Token Authentication

Token authentication is also known as bearer authentication. To use it, you just specify Authorization: Bearer <token>, where the token is a string that represents the user’s identity and permissions. If you have (bear) the token, you can get the appropriate access to the API.

Pros of token authentication

• It's more secure than basic authentication. The token is encrypted, so it can't be decoded and stolen like a username and password. You can also specify an expiration for the token, so it doesn't provide access forever.
• It can also be used for authorization. A bearer token can simplify the authentication and authorization process by providing both at once.

Cons of token authentication

• Tokens have shorter lifespans than usernames and passwords. While the expiration date for a token is a security benefit, it can also be annoying for users that need to generate new tokens often because the old one has expired.

• In the event that a token is stolen, attackers have access to secure data. While token authorization is more secure than basic authentication, it's not foolproof. It's possible for an attacker to get the token and use it to access the data until the token expires.

• It's tougher to implement than basic authentication. There's more work involved in implementing token authorization than the very simple basic authorization.

OAuth authentication

OAuth is an open authorization framework that uses a type of token authentication, but it leverages credentials from one service provider to log into other service providers.

Pros of OAuth authentication

• Creates an easy single sign-on (SSO) experience for users. Users can specify their login credentials once to one service provider in an easy-to-use GUI and use it to generate a token. Then, they can use that authenticated identity across other service providers. For example, you might use OAuth to allow users to log into your application with their Google account.

• It's more secure than basic authentication. Like bearer tokens, OAuth is more secure than basic authentication.

• It can also be used for authorization. Like bearer tokens, OAuth can both authenticate and authorize users.

• It's wildly popular and secure. OAuth is used by most organizations for their APIs, which is a testament to its security (for the reasons mentioned above for token auth). It also means a lot of resources are available to help you implement it.

Cons of OAuth authentication

• In the event that a token is stolen, attackers have access to secure data. Similar to token authorization explained above, OAuth tokens can be stolen and used to get temporary access to the data.
• It's tougher to implement than basic authentication. Like bearer tokens, OAuth requires more work to implement than basic authorization.

API key authentication

API keys are also way more secure than basic authentication and grant access via a string of text, but they are different from token authentication in one crucial aspect.

While token authentication proves who the user is that's accessing the API, it doesn't identify the application making the request. APIs are the opposite of this: they provide info about the application making the request, but they don't supply user-specific information.

Pros of API key authentication

• They facilitate easy programmatic access for your users. Since they're specific to an application and not to the user, they can easily be included in scripts for programmatic access.

• It can also be used for authorization. Like bearer tokens and OAuth, API keys can both authenticate and authorize API access.

Cons of API key authentication

• They're more secure than basic authentication, but less secure than token authentication and OAuth. This is because multiple users can use the same API key for access; it's specific to the application making the request, not the user.
• API keys don't expire. If an attacker gets hold of an API key, it doesn't expire like tokens do, so it can mean they have access to sensitive data for longer.

Note: it's possible to use API keys together with token authentication or OAuth, which mitigates some of the cons.

How to select the right API authentication method

To select the right API authentication method for you, you need to weigh the pros and cons and consider the needs of your organization. It's also important to consider the clients connecting to the API and what they will support.

Are you currently running an API without any authentication at all and need the easiest, quickest security implementation? Basic authentication may be a good stop-gap that you can put in place quickly. On the other hand, if your organization's databases house sensitive user data, you'll want to opt for something more secure, like OAuth or API Key authentication.

You also want to think about the user experience you want to create. Are your users tech-savvy folks that need programmatic access? They might prefer API keys. If, on the other hand, they're looking for an easy login experience for a non-programmatic user, they might prefer OAuth to allow SSO via an application they already know and trust.

No matter which method you choose, you now know the basics of API authentication and authorization. Make sure you're using both to keep your data safe.

Continued Learning and Related Content

• API Gateway vs Load Balancer: Which is Right for Your Application?
• API Gateway vs API Proxy: Understanding The Differences

• Control Plane vs. Data Plane – What’s the Difference?
• What's the Difference: Kubernetes Controllers vs Operators?