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An application programming interface (API) key is a code used to identify and authenticate an application or user. API keys are available through platforms, such as a white-labeled internal marketplace. They also act as a unique identifier and provide a secret token for authentication purposes.

APIs are interfaces that help build software and define how pieces of software interact with each other. They control requests made between programs, how those requests are made, and the data formats used. They are commonly used on Internet-of-Things (IoT) applications and websites to gather and process data or enable users to input information. For example, users can get a Google API key or YouTube API keys, which are accessible through an API key generator.

An API key is passed by an application, which then calls the API to identify the user, developer, or program attempting to access a website. It can help break development silos and will typically be accompanied by a set of access rights that belong to the API the key is associated with. 

Why Use API Keys

API keys are commonly used to control the utilization of the API’s interface and track how it is being used. This is often as a precaution to prevent abuse or malicious use. Common reasons why to use API keys include:

API Keys for Project Authorization

API keys are used in projects, providing authentication to identify users and the project itself. API keys provide project authorization through:

Project Identification

API keys can be used to identify a specific project or the application making the call to the API. While API keys are not as secure as the tokens that provide authentication, they help identify the project or application that makes the call. This ensures they can also be used to designate usage information to a specific project and reject unauthorized access requests.

Project Authorization

API keys are commonly used to check that the application making the call to the API has access to do so. Authorization will also check that the API being used in the project is enabled.

API Keys for Authentication of Users

Authentication schemes are used to identify the caller requesting API access. Endpoints or devices can check the authentication token to confirm the user has permission to make the call, while the API server can use authentication token information to make a decision on whether to authorize a request. 

API keys can be used for the following authentication purposes:

User Authentication

This verifies that the person making the call is the person they claim to be by checking or authenticating the identity of the user.

User Authorization

This checks whether the user making the call has permission to make the kind of request they have issued.

Security of API Keys

API security is increasingly important, especially given the rapid rise in IoT usage. APIs transmit sensitive user data between the applications and systems they access and interact with. Therefore, an insecure API could be a high-value and easy target for attackers to obtain critical data and gain unauthorized access to computers and networks. They are often the subject of broken access control, distributed denial-of-service (DDoS), injection, and man-in-the-middle (MITM) attacks, which means they need to be extremely secure.

A common method for securing your API is representational state transfer, or REST API, which controls the data that an API can access as it operates through a Hypertext Transfer Protocol (HTTP) Uniform Resource Identifier (URI). This helps prevent attackers from introducing malicious data to an API.

When To Use API Keys

There are several common usages for API keys, including:

Block Anonymous Traffic

Anonymous traffic can be an indicator of potentially malicious activity or traffic. API keys can identify application traffic, which can be used to debug issues or analyze application usage.

Control the Number of Calls Made to Your API

Controlling the number of calls made to an API helps to govern API consumption, limit traffic and usage, and ensure only legitimate traffic accesses the API.

Identify Usage Patterns in Your API's Traffic

Identifying usage patterns is crucial to spotting malicious activity or issues within the API.

Filter Logs

Activity on the API server can be logged as a series of events, which can be filtered by the specific API key.

API Keys Cannot Be Used For

API keys cannot be used for the following purposes:

Secure Authorization

API keys cannot be used for secure authorization because they are not as secure as authentication tokens. Instead, they identify an application or project that calls an API.

Identifying the Creators of a Project

API keys are generated by the project making a call but cannot be used to identify who created the project.

Identifying Individual Users

API keys are used to identity projects, not the individual users that access a project.

How Fortinet Can Help

Fortinet provides API security that protects organizations against data breaches and security attacks that target APIs. It provides Security Assertion Markup Language (SAML) capabilities that enable them to authenticate and authorize users across all their systems and APIs, which is crucial to mitigating cyberattacks. 

Fortinet also provides network access control (NAC), a zero-trust network solution that enhances visibility into IoT devices accessing corporate networks.