Legacy in-vehicle networks operated under the flawed perimeter model: anything inside the vehicle's physical wiring harness was considered trusted. Modern software-defined vehicles enforce Zero Trust: every microservice, whether steering actuation or climate display, must mutually authenticate using cryptographic tokens (mTLS, SPIFFE/SPIRE) on every transaction. Never trust, always verify.
In an SDV, how does the steer-by-wire daemon know that a incoming gRPC trajectory command comes from the verified autonomous driving planner, and not an injected malware thread? The SPIRE agent queries the Linux kernel for the caller's process ID, inspects its binary hash in `/proc/<pid>/exe`, validates its SELinux security context, and matches it against cryptographic attestation rules before minting a short-lived X.509 certificate. If the binary hash does not match the signed release manifest, communication is denied.