Dell Update Packages User's Guide

A Trusted Platform Module (TPM) is a secure microcontroller with cryptographic capabilities designed to provide basic security‑related functions involving encryption keys. It is installed on the motherboard of the system, and communicates with the rest of the system using a hardware bus. You can establish ownership of the system and its TPM using the BIOS setup commands.

TPM stores the platform configuration as a set of values in a set of Platform Configuration Registers (PCRs). Thus one such register may store, for example, the motherboard manufacturer; another, the processor manufacturer; a third, the firmware version for the platform, and so on. Systems that incorporate a TPM create a key that is tied to platform measurements. The key can only be unwrapped when those platform measurements have the same values that they had when the key was created. This process is called sealing the key to the TPM. Decrypting is called unsealing. When a sealed key is first created, the TPM records a snapshot of configuration values and file hashes. A sealed key is only unsealed or released when those current system values match the ones in the snapshot. BitLocker uses sealed keys to detect attacks against the integrity of the system. Data is locked until specific hardware or software conditions are met.

BitLocker is designed for systems that have a compatible TPM microchip and BIOS. A compatible TPM is defined as a version 1.2 TPM. A compatible BIOS supports the TPM and the Static root of Trust Measurement. BitLocker seals the master encryption key in the TPM and only allows the key to be released when code measurements have not changed from a previous secure boot. It forces you to provide a recovery key to continue boot if any measurements have changed. A one‑to‑many BIOS update scenario results in BitLocker halting the update and requesting a recovery key before completing boot.

BitLocker protects the data stored on a system through full volume encryption and secure startup. It ensures that data stored on a system remains encrypted even if the system is tampered with when the operating system is not running and prevents the operating system from booting and decrypting the drive until you present the BitLocker key.

TPM interacts with BitLocker to provide protection at system startup. TPM must be enabled and activated before it can be used by BitLocker. If the startup information has changed, BitLocker enters recovery mode, and you need a recovery password to regain access to the data.