Hardware Root of Trust#

In the realm of cybersecurity, establishing a foundation of trust is paramount to safeguarding digital assets and sensitive information. Ultimately, there has to be a point within the system architecture which we assume is a secure place from which to start our security processes. Ideally, this should begin with the system hardware, allowing us to boot to the operating system with confidence in maintaining confidentiality, integrity and availability - at least to that point. The Hardware Root of Trust (HRoT) aims to fulfil this function by laying the groundwork for a robust security architecture that bolsters the integrity of hardware and ensures the confidentiality of critical data.

Understanding the Hardware Root of Trust#

At its core, the Hardware Root of Trust comprises a set of hardware-based mechanisms and protocols that create a chain of trust within a computing system. At the root of this chain is often a hardware security module (HSM) or Trusted Platform Module (TPM) which provides critical cryptographic functions such as key storage and computation – these keys and functions are then used to validate each layer of hardware, with each then validating the next. The HRoT forms the bedrock upon which other security layers are then constructed.

Tip: The Hardware Root Of Trust is easier to understand once you have a grasp of how secure boot works, we’d recommend reading that article before going any further!

Components of the Hardware Root of Trust#

Understanding the Hardware Root of Trust is easiest when you have a clear picture of how the components function together.

  • Trusted Platform Module (TPM) - Central to HRoT is the Trusted Platform Module (TPM), a specialized microcontroller that assumes the role of a secure vault. Within this secure storage vault, cryptographic keys, certificates, and sensitive data are stored with the highest level of protection. Beyond storage, the TPM offers cryptographic functions and attestation capabilities, enabling the system to verify its own integrity to external entities.

  • Secure Boot Process - Securing the system’s boot process is vital in HRoT. Using the features provided by the TPM, the secure boot process ensures that the system initiates with firmware and software components that can be trusted. This guards against the execution of unauthorized or tampered code during boot-up, thereby pre-emptively defending against attacks attempting to infiltrate the system’s core.

  • Remote Attestation - HRoT extends its impact beyond local confines through remote attestation. This mechanism empowers a system to provide evidence of its own integrity to a remote verifier, once a boot is complete and validated. This capability is crucial for establishing trust between interconnected devices in scenarios like cloud computing and the Internet of Things (IoT), where remote parties need assurances about the system’s security status.

  • Key Management - HRoT depends upon meticulous key management. Cryptographic keys are generated within the secure confines of the hardware, ensuring that they are shielded from external access. This ensures that cryptographic operations are conducted in a secure environment and protected against unauthorized intrusion.

  • Chain of Trust - The concept of a Chain of Trust ensures a sequenced hierarchy of reliability. The trust established by the HRoT extends through successive layers of the system’s architecture, with each layer cryptographically validating the integrity of the next. This forms an unbroken continuum of trust, starting from the root (Usually the TPM or HSM) where each link is fortified by the preceding one.

Benefits of the Hardware Root of Trust#

When these elements all work together, security professionals can be confident that each aspect has properly validated the one which follows it, which gives us a safe starting point to which we can assume systems are secure. Most typically this will be the boot sequence, with the HRoT functioning to ensure that at boot time at least, the system is in the correct state.

The key advantages of the Hardware Root of Trust are:

  • The Hardware Root of Trust establishes a robust foundation for all subsequent security measures.

  • The ability to remotely attest to a system’s integrity, enabling trust to be extended across networked devices in diverse contexts like cloud computing and the Internet of Things.

  • HRoT thwarts common threats such as malware and unauthorized code execution by enforcing a secure boot process, a vital barrier against compromise.

  • The secure storage of cryptographic keys and sensitive data assures confidentiality, impeding unauthorized access even in the face of a breach.

Final words#

The Hardware Root of Trust is a concept which illustrates how a well designed system can act as a self-validating chain, providing a high degree of security assurance. By establishing a foundation of trust, HRoT ensures that every layer of a system’s architecture adheres to the highest standards of security and integrity.