Defining API security in OpenAPI specification

Introduction

When designing an API, security is a critical consideration. The OpenAPI specification provides several options for defining API security. In this post, we'll take a deep dive into the different security options available in the OpenAPI specification and how to document them.

API Security Options

There are several API security options available in the OpenAPI specification:

HTTP Authentication

HTTP authentication is a common method of API security. The OpenAPI specification supports two types of HTTP authentication: Basic and Digest.

To define HTTP authentication in your OpenAPI specification, you need to use the securitySchemes object. Here's an example of how to define basic authentication:

securitySchemes:
  basicAuth:
    type: http
    scheme: basic

You can then reference this security scheme in your API paths and operations using the security property:

security:
  - basicAuth: []

API Keys

API keys are a simple and effective way to secure your API. To use API keys, clients must send an API key with each API request.

To define API keys in your OpenAPI specification, you need to use the securitySchemes object. Here's an example of how to define an API key security scheme:

securitySchemes:
  api_key:
    type: apiKey
    name: api_key
    in: header

You can then reference this security scheme in your API paths and operations using the securityproperty:

security:
  - api_key: []

OAuth2

OAuth2 is a widely-used standard for authorization. The OpenAPI specification supports several OAuth2 grant types, including authorization code, implicit, password, and client credentials.

To define OAuth2 in your OpenAPI specification, you need to use the securitySchemesobject. Here's an example of how to define an OAuth2 security scheme:

securitySchemes:
  oauth2:
    type: oauth2
    flows:
      password:
        tokenUrl: https://example.com/token
        scopes:
          read: Grants read access
          write: Grants write access

You can then reference this security scheme in your API paths and operations using the security property:

security:
  - oauth2: ['read', 'write']

Conclusion

In this post, we've taken a deep dive into the different API security options available in the OpenAPI specification. We've covered HTTP authentication, API keys, and OAuth2. By understanding these security options and how to document them in your OpenAPI specification, you can create secure and reliable APIs that meet the needs of your users.