Hardware Root of Trust

The HRoT contains the first code executed by the processor at power-on, stored in non-writable masked ROM or one-time programmable memory. This code is physically impossible to alter after manufacturing, ensuring the boot sequence always begins from a known-good state. Any attempt to modify this initial firmware would require physical silicon alteration, making it the ultimate trust anchor in the chain of trust.

A unique, device-specific Endorsement Key (EK) is burned into the HRoT during manufacturing. This asymmetric key pair, generated in a controlled factory environment, provides a cryptographically verifiable identity for the platform. The private key never leaves the hardware, enabling:

• Device authentication to networks and services
• Binding of software licenses to specific silicon
• Foundational key derivation for all platform secrets

The HRoT provides a shielded location for cryptographic material, isolated from the main operating system and application processors. This secure key storage is implemented in dedicated, access-controlled memory that resists physical probing, side-channel analysis, and fault injection attacks. Private keys generated or stored within the HRoT are never exposed in plaintext to any external bus or untrusted software, preventing extraction even if the OS is fully compromised.

The HRoT implements a measured boot process that cryptographically verifies each stage of firmware before execution. Starting from the immutable ROM, each subsequent bootloader and OS component is hashed and its signature validated against a stored public key or fused digest. If verification fails at any stage, the boot process halts, preventing the execution of rootkits, bootkits, or unauthorized firmware modifications that could compromise the entire software stack.

The HRoT can generate a cryptographically signed report—a quote—containing platform measurements and the device's unique identity. This allows a remote verifier to:

• Confirm the platform is genuine hardware
• Validate the exact firmware and software versions running
• Establish trust before provisioning secrets or granting network access This remote attestation protocol is the foundation for Confidential Computing and zero-trust network architectures.

HRoT hardware is engineered with multiple layers of defense against physical adversaries. These include:

• Active shielding that detects drilling or decapsulation attempts
• Environmental sensors monitoring voltage, temperature, and clock glitches
• Secure manufacturing processes that prevent supply-chain key injection Upon detecting a tamper event, the HRoT can instantly zeroize all stored secrets, rendering extracted silicon useless to an attacker.

A dedicated, passive microcontroller that implements the Hardware Root of Trust specification. It securely stores platform measurements, cryptographic keys, and certificates. Unlike a CPU-based TEE, the TPM is a discrete, tamper-resistant chip that provides measured boot and remote attestation capabilities but does not execute arbitrary application code.

• Stores Endorsement Key (EK) burned in at manufacture
• Provides Platform Configuration Registers (PCRs) for integrity measurement
• Performs cryptographic operations without exposing private keys to the host OS

A boot process where each firmware and software component is cryptographically hashed and the measurement is recorded into a Platform Configuration Register (PCR) before execution. This creates an unforgeable audit log anchored in the Hardware Root of Trust.

• Extends PCRs using the formula: New PCR = Hash(Old PCR || New Measurement)
• Enables detection of rootkits and bootkits
• Forms the evidence basis for remote attestation

A security standard that ensures a device boots using only software that is trusted by the Original Equipment Manufacturer (OEM). The Hardware Root of Trust stores the authorized signing keys and verifies digital signatures of each boot component before allowing execution.

• Prevents loading of unauthorized UEFI drivers and OS bootloaders
• Establishes the initial link in the chain of trust
• Revocation of compromised keys via Key Exchange Key (KEK) updates

A physical hardware security primitive that exploits microscopic manufacturing variations in silicon to generate a unique, device-specific fingerprint. This fingerprint derives a root key without storing it digitally, making extraction via physical probing or reverse engineering infeasible.

• Generates SRAM PUF keys from power-up state patterns
• Eliminates the need for non-volatile key storage
• Provides intrinsic tamper-evidence: physical attacks alter the PUF response

A hierarchical validation sequence starting from the immutable Hardware Root of Trust and extending through each subsequent software layer. Each stage cryptographically verifies the next before passing control, ensuring that a single compromised component breaks the chain and prevents the system from reaching a trusted state.

• Root of Trust for Verification (RTV) validates the first mutable code
• Root of Trust for Measurement (RTM) records integrity metrics
• Extends from Boot ROM → Bootloader → OS Kernel → Applications

Cryptographic operations that bind secrets to a specific platform state. The Hardware Root of Trust derives unique keys based on its immutable identity and the current PCR values, ensuring secrets can only be unsealed when the platform is in a known-good configuration.

• Seal: Encrypts data to a specific PCR state
• Unseal: Decrypts only if current PCRs match the specified policy
• Prevents offline decryption if the disk is moved to another machine