Validating TPM Measured Boot and Attestation
Legal Notice: Perform TPM operations only on systems you own or are authorized to assess. Some operations (clearing the TPM, taking ownership, defining NV indices) are destructive or can lock the device. This skill is for defensive integrity verification and authorized assessment.
Overview
A Trusted Platform Module (TPM 2.0) is a hardware root of trust that supports measured boot: each stage of the boot chain hashes ("measures") the next stage and extends that measurement into a Platform Configuration Register (PCR) before handing off control. PCRs cannot be set arbitrarily — they can only be extended (new = hash(old || measurement)), so the final PCR value is a tamper-evident summary of everything that executed. The TCG firmware profile assigns specific meanings: UEFI firmware code/config measure into PCR 0–7 (PCR 7 specifically captures Secure Boot policy), bootloaders measure the kernel into PCR 8–9, and Linux IMA measures executables into PCR 10.
Two complementary verifications matter. Local validation reads current PCRs (tpm2_pcrread) and replays the TPM event log (tpm2_eventlog on `/sys/ke…
