RAUC Streaming OTA: When the Sandbox User Can't Reach the TPM

Switching RAUC’s streaming mTLS client key from a file path to a PKCS#11 URI produced a one-line error with no obvious cause. The real problem was not the module path, not the engine, and not a missing PIN — it was the sandbox user’s group membership and what tpm2-pkcs11 needs to initialise.

April 21, 2026 · 7 min · Umair Ahmed Shah