# Mutual TLS in OpenAPI

# The Mutual TLS security scheme in OpenAPI

Mutual TLS (mTLS) is a security protocol that enhances the security of API
communication by requiring both the client and server to authenticate each other
using digital certificates. This two-way authentication ensures that only
trusted parties can establish a connection, providing an additional layer of
security.

OpenAPI lets you define a Mutual TLS security scheme using the `mutualTLS` type.

## Defining a Mutual TLS security scheme

Define a Mutual TLS security scheme in OpenAPI using the following
structure:

```yaml
components:
  securitySchemes:
    MutualTLS:
      type: mutualTLS
      description: Mutual TLS authentication for secure API communication.
```

The `mutualTLS` type requires no additional fields, as its primary purpose is
to indicate that the API requires mutual TLS authentication. However, you can use the
`description` field to provide API users with additional information about how to
obtain a certificate.

```yaml
components:
  securitySchemes:
    MutualTLS:
      type: mutualTLS
      description: >
        To access this API, you must provide a valid client certificate. 
        Please submit a request to the [infrastructure team](https://example.com) with 
        full information about what this application is to obtain a certificate.
```

Learn more about mutual TLS in the [OpenAPI Specification](https://spec.openapis.org/oas/v3.1.0#mutual-tls-security-scheme) or the [Cloudflare Learning Center](https://www.cloudflare.com/learning/access-management/what-is-mutual-tls/).