The deeper penetration of cloud and internet-based applications is at an all-time high. Organizations are using project management, budgeting, team collaboration, automation, and a couple of other kinds of applications to attain perfection and productivity in the key workflow.
Regardless of the type of application used, API is always behind the curtain. Better to call it the means of communications for applications, without APIs, no application development is complete.
If codes are the building blocks of an application, API is the cement keeping every block or section joined as it empowers an app to communicate with the rest of the world.
The extended use of APIs has increased its exploitation risk. Each time an API endpoint communicates with the server, it has to change to get affected by malicious links, traffic, and even wrong usage. To control the above, we have API authentication.
Let’s dig a little further to find out about it in detail.
Authentication vs Authorization In API
Before we learn what web API authentication is, let’s find out what it is not.
To begin with, it’s not completely similar to authorization. Though these 2 terms collide and are used extensively in security domain when it’s about APIs, using them interchangeably will be wrong.
API authorization is all about allowing a user to use API in a permitted manner. It determines whether the concerned user is entitled to take the actions. For instance, 3rd party API users are not eligible to make changes in the source code. For that, someone with admin-level authority is needed.
With means like OAuth, API Keys, and many more, API developers can decide which user can take what actions. It ensures controlled and monitored usage of API while helping greatly in its exploitation.
It ensures that the access is happening with strict adherence to rules & regulations. If any clause is overruled, it won’t make access possible. This is the stage that follows the authentication.
For effective API security, it is essential to have a way to authenticate users. After verifying their identity, authorization must be a part of your strategy too. Alone, auth mechanisms hardly make any sense.
API authentication deals with different aspects of API security. It’s enough even when it's used alone. It checks whether the user is who s/he is claiming to be.
The simplest explanation of this process is showing the employee ID card or ID credentials before accessing any company-owned resource or entity.
What is an API authentication?
Just now we cleared the air on the fact that it is not same as authorization. So, what it is then?
Well, it is the procedure that checks/confirms the prospective API user identity to prevent unauthorized access.
Just as one has to provide a passport as proof of identity while visiting another country, API users must provide an API keys or any similar credential to verify themselves before starting using the respective API.
This enables API developers to ensure that only verified or those who have paid for the APIs are accessing this powerful application communication tool. In a complex ecosystem, it’s hard to track API usage. But, implementation of API authentication practices automates user verification at every stage and even helps in forced access.
Common Methods of API Authentication
Now, the concerning aspect is how verification takes place. Well, we have four globally acceptable methods for this job.
HTTP Basic Authentication
Probably the oldest verification approach, HTTP basic authentication involves taking the help of an HTTP user agent whose job is to provide distinctive usernames and login passwords for every current API user. As soon as a user gets registered with an API, the HTTP user agent allots these unique credentials.
The users can log in to the API with the help of those details. No session IDs, cookies, or any lengthy login process is involved. The core of everything lies in the HTTP Header which eliminates the need for a handshake and automates the entire process from the basics.
The used HTTP Header makes external device-based communication possible. The communication channel is only created when authentication succeeds. An authentication session is generated using Basic Authentication while sessionid makes service availability possible in a highly stateful ecosystem. Sounds easy, right?
Yes, it’s straightforward but it’s not flawless. If the process lacks end-to-end encryption, the chances of a MITM attack are high. Skilled hackers will be able to break into the process and steal the login credential. If that happens, they will use the credential and start using API for ill-purposes.
This made the world look for improved and enhanced API authentication methods.
A modern API security approach, OAuth merges both the API authorization and authentication process so that the security wall is not permeable. This is why companies like Facebook, Google, and Twitter are using it for their API products. Note it here, it’s not necessary to deploy both aspects.
You can bring OAuth into action only for authorization. Speaking about its functionality, it goes like this:
Step 1: User initiates the login process.
Step 2: Concerned system asks for authentication in token form.
Step 3: User forwards the token to the authentication server.
Step 4: Server accepts or rejects the request based on the pre-defined authentication rules.
It seems simple from the surface but a complex algorithm runs behind it. As the token remains private, security is not compromised in this authenticate technique. It’s preferred by many because it defines the scope and validity of API security.
Presently, OAuth 2. is live and is the most preferred OAuth version and it’s easy to scale. Other than this, multiple OAuth varieties like one-legged and three-legged OAuth also exist. Use the first variety when sensitive data isn’t part of authentication. Consider read-only data a part of such data.
The latter variety, three-legged OAuth, is suitable for APIs dealing with mission-critical information. The related entities here are the main authentication server, the API server, and the end-user.
Even though OAuth alone is quite effective, combining it with OpenID Connect endows API developers with an utterly powerful security profile for APIs of all sorts.
It activates in the identity layer and assists in verifying the user identity by authentication-server side authentication.
API Key Authentication
API developers consider it as the fastest way to get started with APIs. Not only it showed up as a fix for pitfalls that the first API authentication method cause, its adoption is way too easy too.
As a remedial solution, it started generating a distinct value and pairing it with the first-ever user login session. For every next login, users have to enter that value to complete the process. The API key is unique because it uses the IP data and a few hardware details of the corresponding users.
We wished it to be all good stuff. But, this doesn’t always happen. API keys have high theft possibilities. Any weak network transmission can expose it and its related data causing severe threats.
Lastly, you can authenticate APIs without actually going through the exhaustive authentication process. The only thing developers have to do is to request the concerned URLs and get endowed with an appropriate response. Mostly, internal APIs are suitable for this method. But, as its viability is of the not highest grade, we don’t recommend it at all.
REST API Authentication: Quick Tips
One of the earliest API varieties, REST API, is used widely. With the REST framework, more and more web APIs are developed as it is easy and scalable. While you use REST for API development, don’t overlook the API authentication best practices that involve using tokens for validation, SSL usage, stopping the spread of error messages, and parameter validation.
APIs offered as a product are best protected with the help of a private key and client ID or deploying a subscription mechanism to keep tabs on access level, expiration dates, and call rates. Make sure private keys are accessible during the time of need.
For web-based REST API, adoption of TLS is non-negotiable as it restricts the concerned API to share information to unverified resources. The encryption model protects the data in transit and prevents any invasion.
It’s better to make your REST APIs to be optimized for SSO or Single Sign On. With this approach, API providers take the help of a 3rd party provider for user verification. The 3rd party service provider allows a token to the user and API provider. During the login process, a token of both sides will be accessed and login is only possible when two tokens are mismatched.
Never have one kind of access strategy for all kinds of API endpoints. Try to diversify access as per its usage. You can easily make this happen by storing the permissions with the API keys in the strings list form. You don’t have to use complex strings for this job. Strings as simple as ‘write’ and ‘read’ are enough.
Adopt these and your REST APIs will be adequately protected from invasion or ill usage.
Tips to Choosing Correct API Authentication Method
The assorted that one gets to enjoy at API authentication practices tend to leave the adopter confused. Which one to pick and which one to drop? This constant struggle can take a toll on you. However, you don’t have to hustle too much as we’re going to explain how to make a wise choice when it comes to selecting a viable API authentication mechanism.
Understand the level of security you’re expecting
First thing first, you need to sort out your API security expectation. Figure out what kind of resilience you’re seeking. For instance:
Do you want to protect the client-side aspect only or the server-side will also be considered?
Are you looking for an easy deployment approach?
Is scalability counted?
Sort out all these things and then make a choice accordingly. Compare the available method and pick the one that is matching the best to your requirements. Consider this, you should use API Keys if you need to implement API authentication at the both application developer and provider level.
If you’re looking for a scalable solution, you can place your bet on OAuth Authentication. Since its launch, it’s evolving continuously and providing time-relevant security solutions. Currently, its 2.0 version is live and is winning hearts because of its outstanding scalability.
Moving from one version to another is smooth if you adopt OAuth. But, its implementation and maintenance aren’t an easy task. It’s daunting and demands commitment on every front. So, make a choice accordingly.
Move from easy to complex
Each method has a different complexity level and as a beginner, you must start with a simple approach first. Get a hang of the process and how effective authentication is. Once this is clear, move to a complex and effective approach.
If you adopt a complex approach first, the chances of being fed up at an early stage are high. This isn’t going to take you anywhere.
Pay attention to the existing authentication infrastructure
If you already have an authentication strategy in place, study it thoroughly and scale only when you find solutions that can fit well into it. What we meant to say here is that your existing and future authentication approaches should get along well.
For instance, if you try to combine HTTP Basic Authentication and OAuth 2.0 then chances are high that the API will only access OAuth if you’re using the same HTTP Header. You need to use distinctive authorization entities. This can solve the incompatibility issue up to great extent. So, it's important to keep the compatibility factor of two different API authentication mechanisms into consideration before merging them,
You have a set of powerful APIs to offer. But, with the lack of proper and viable security measures, your APIs are not going to earn a name and fame in the market. The lack of security can make all your API development efforts go wasted. Are you ready to take that chance?
If not, start to understand what API authentication means and how to bring it into action. The excerpt of the above text concludes:
It’s not API authorization
It must be implemented to every API, no exceptions are entertained
Multiple methods are available
Each method has a fair share of pros and cons
Adoption depends on the expectations
Careful inspection of the best approach to authenticate users can result in better decision-making
All of this may seem overwhelming but sorting them out is important if, as an API provider or developer, you do not want your APIs to be over-exposed and become a headache.
API authentication applied alone or in combination with other approaches, is a viable method. Adopt it today and enjoy everlasting API security. Always remember, a secured API is what is going to rule.