Security

The Link API is secured by OAuth2 (mandatory for production access) and mTLS (optional).

Mutual TLS (mTLS) and OAuth2 Client Credentials are two distinct security mechanisms that can complement each other to provide robust authentication and secure communication in API integrations.

Note: For testing purposes we also support an internal authentication method that requires client_id/client_secret with each API call. The code examples in this document use this particular method.

How mTLS and OAuth2 Client Credentials Complement Each Other

When used together, mTLS and OAuth2 Client Credentials Grant provide a powerful combination of strong client authentication and fine-grained authorization. Here’s how they complement each other:

Dual Authentication and Authorization

• mTLS provides a strong, cryptographic client authentication mechanism, ensuring that only authorized clients (those with valid client certificates) can establish a connection.
• OAuth2 Client Credentials provides a token-based mechanism for authorizing the client’s access to specific APIs or resources. The access token contains information about the client’s permissions and access scope.

Layered Security

By using both mTLS and OAuth2, you establish multiple layers of security. Even if an access token is somehow obtained by an attacker, mTLS ensures that only clients with a valid certificate can connect. Conversely, even if a client possesses a valid certificate, it still needs a valid access token to access protected resources.

Preventing Token Theft and Replay Attacks

With mTLS, the secure communication channel prevents token theft during transmission. Even if a token were somehow intercepted, it would be useless without the client’s certificate to establish the connection.

Enhanced Security for Sensitive Applications

For highly sensitive applications, combining mTLS with OAuth2 Client Credentials ensures that only authenticated clients (validated by their certificates) and authorized clients (validated by their tokens) can access resources. This is particularly important in zero-trust environments or for internal microservices communication.

Compliance and Regulatory Requirements

Some industries require strong client authentication and end-to-end encryption. Combining mTLS with OAuth2 can help meet these regulatory requirements by ensuring secure communication and controlled access.

Summary

By combining mTLS with OAuth2 Client Credentials Grant, you gain the benefits of both strong client authentication and fine-grained access control, enhancing the overall security posture of your application.