Q41: What is Mutual TLS (mTLS) and how does it secure API communications?
In standard TLS, only the server presents an X.509 certificate to prove its identity to the client.
In Mutual TLS (mTLS), both the client and server present and validate X.509 cryptographic certificates during the initial TLS handshake.
Benefits for API Security:
- Establishes cryptographically authenticated transport channels before any HTTP application bytes are processed.
- Protects microservices against unauthorized connection attempts, IP spoofing, and rogue client access.
Key Takeaways
- mTLS enforces bidirectional X.509 certificate authentication during the TLS transport handshake.
- Commonly deployed in zero-trust service meshes (Istio, Linkerd) and financial open banking APIs.