API Authentication: what it is, how it works and benefits

When we talk about API Authentication Methods, we refer to the different authentication systems used in API infrastructures to verify the identity of users.

There are various API authentication mechanisms: some are encrypted and some are in plain text, some use a username and password, some use API keys, and others work through tokens.

Each authentication method has its advantages and disadvantages, characteristics that make it more or less suitable for a given application. However, all these processes have a common goal: to protect sensitive data and ensure that the API is not misused.

What is API Authentication?

API Authentication is the process that validates the identity of users when they try to connect to an application. API authentication mechanisms ensure that only recognized users can access applications, and for this reason, they are the foundation of API infrastructure security.

When a user makes an API request, a software protocol sends the access credentials that must be used for the request.

The operation of this mechanism can vary greatly from one case to another: for example, if you are using API Basic Authentication, the user will enter a username and password within the header of each API call, while if you choose to implement the OAuth method, the process involves a more complex, but also more secure, flow.

Let’s see what the most used API authentication methods are and how they work.

HTTP Basic Authentication

This authentication method is by far the simplest to implement in your systems, as it does not require login pages, IDs, or handshakes of any kind.

In HTTP Basic Authentication, the client sends requests by including a username and password (encoded in Base64) within the HTTP header used for transmission. The credentials must be included in every API call.

It is generally discouraged in contexts that handle sensitive data due to its inherent vulnerability: the credentials are quite easy to decode, so every time the username and password are shared, there is a risk they could be intercepted by malicious users. For this reason, it is recommended to use it only over HTTPS (SSL).

API Token Authentication: Bearer Authentication

Another possible method for API Rest Authentication is the Bearer token system. In this type of HTTP authentication, the client has a token that allows access to a specific resource and must include it in the Authorization header when making requests to protected URLs. If the request does not contain a valid token, it is rejected.

This type of authentication is much more secure: firstly, using tokens avoids sending credentials within every request. Additionally, unlike HTTP Basic authentication credentials, tokens have an expiration date.

API Key Authentication

API Keys are fundamental elements of API authentication: conceived as a possible solution to the problems of HTTP Basic authentication, API keys are unique values assigned to each user upon first access, and are subsequently used to prove that it is the same user.

API Keys can be used in combination with various authentication methods, and in practice, they behave exactly like a password. Depending on the settings, the client can…