Security

mTLS

Mutual TLS — both client and server present certificates.


In plain terms

Service mesh default for cross-service auth. Token-binding alternative is DPoP.

Origin

Mutual TLS is just TLS with client authentication enabled — the option has been in TLS since SSL 3.0 (1996). Made operationally practical at scale by service-mesh tooling around 2017.

Where it shows up in production
  • Istio / Linkerd Automatic mTLS between every pod via injected sidecars. Zero-touch for the application.
  • SPIFFE / SPIRE Workload identities issued as X.509 certs; mTLS is the default transport.
  • Cloudflare Access Replaces VPNs with mTLS-authenticated zero-trust access to internal services.
On Semicolony
Sources & further reading
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