We all know that APIs are software protocols and tools that help clients and servers to communicate. However, the bugging question is; how does the server know that clients are who they claim to be for communication to take place. This write-up explores ways in which the identity of clients is stamped for them to be able to access their respective servers in what is referred to as API Authentication.
So, what is API Authentication?
Since API is a profound entity with an external resource that has the capability of accepting and responding to protected resource requests by users and clients, they must be equipped to ensure that applications and clients trying to access data are authentic, so that they can proceed to authorized full access when identity is confirmed. The processes of certifying the identity of users trying to access resources on the server and this is what is known as API authentication. And, before we delve deeper into this topic, let’s differentiate between authentication and authorization.
Authentication vs Authorization
Authentication is when an entity verifies the identity of a user. In other words, it proves that the clients trying to access a remote server are really who they say they are.
On the other hand, authorization is the next thing that happens after successful authentication. It is the approval that a certain client has the right to make a request. Simply, authorization is when an entity verifies that you have the right to access data or information on a given server.
However, as we scour through this topic of API authentication, it’s crucial to understand that we’re discussing a system that only proves identity (API Authentication).
Which are the most Common Methods of API Authentication?
Although there are several methods of API authentication, here are some of the most popular:
- HTTP Basic Authentication
- API Key Authentication
- OAuth Authentication
HTTP Basic Authentication
HTTP Basic Authentication is the simplest form of identification. This technique combines username and password to form a single value and passes it through a special HTTP header known as authorization where they are encoded with Base64. Therefore, when a client makes a request, the server checks the Authorization header and compares it to the credentials (username and password) it has stored. If they match, the server fulfills the client request, and if not, a special status code is sent back to inform clients that authentication has failed and their request denied.
API Key Authentication
API Key authentication is a technique that was invented to overcome the weaknesses of shared credentials which was a big problem in HTTP Basic authentication. The API key is usually a long series of numbers and letters that you either include in the request header or request URL. When the client authenticates the API key, the server stamps their identity and allows them to access data. API vendors might provide you with a public and private key depending on your needs, where the former can be used to limit users to certain functions, and the latter acts like a password that allows you full access.
Although this scheme is highly reliable, there some few tips that can make the API more secure:
- Make sure that you use HTTPS at all times.
- Keep it simple
- Avoid exposing information on URLs
- Use password hash
- Install some parameter validation
OAuth Authentication
Technically, Oauth is a technique that does both authentication and authorization. It is a form of API authentication that gives applications with the ability to communicate with API server to provide access. When a user logs into the system, it requests authentication in the form of a token. The client is required to forward the request to an authentication server, which either allows or rejects this it. OAuth authentication is fundamentally a more secure and powerful system than the rests, and it’s quickly becoming the number one choice for many clients and applications.
