Securing Microservices: mTLS in Kubernetes

Zero Trust mandates that internal traffic be encrypted and authenticated. **mTLS (mutual TLS)** achieves this by requiring both client and server to present certificates. In Kubernetes, Service Meshes like Istio automate this entirely.

How Istio Handles mTLS

sequenceDiagram
    participant PodA as Pod A (Envoy Sidecar)
    participant PodB as Pod B (Envoy Sidecar)
    participant Istiod as Istiod Control Plane
    
    Istiod->>PodA: Push Certificate
    Istiod->>PodB: Push Certificate
    PodA->>PodB: mTLS Connection
    PodB-->>PodA: Verify Client Cert

Enabling Strict Mode

apiVersion: security.istio.io/v1beta1
kind: PeerAuthentication
metadata:
  name: default
  namespace: my-namespace
spec:
  mtls:
    mode: STRICT

Key Takeaways

• Certificate rotation is automatic (usually 24 hours).
• Use AuthorizationPolicies to control which services can talk to each other.