Service-to-Service Authentication and Authorization#

In a microservice architecture, services communicate over the network. Without authentication, any process that can reach a service can call it. Without authorization, any authenticated caller can do anything. Zero-trust networking assumes the internal network is hostile and requires every service-to-service call to be authenticated, authorized, and encrypted.

Mutual TLS (mTLS)#

Standard TLS has the client verify the server’s identity. Mutual TLS adds the reverse – the server also verifies the client’s identity. Both sides present certificates. This provides three things: encryption in transit, server authentication, and client authentication.