Introduction to Hardware and Hardware Security

Hardware refers to the physical components of technology, encompassing computer systems and embedded hardware. Similar to software, hardware is also vulnerable to security threats, necessitating robust security measures.

Hardware Security

Hardware security is critical because, like software, hardware can have vulnerabilities that pose significant risks. For software, common security mechanisms include Control-flow Integrity (CFI), Address Space Layout Randomization (ASLR), Web Application Firewalls (WAF), and Intrusion Detection and Prevention Systems (IDPS). Below is a comparison of typical software and hardware vulnerabilities:

Software Vulnerabilities and Threats:

1. Buffer overflows

2. Denial of service (DoS)

3. Privilege escalation

4. Malware

5. SQL Injection

Hardware Vulnerabilities:

1. Row hammer

2. Meltdown

3. Thunderclap

4. Screwed Drivers

5. Foreshadow

Common Weakness Enumeration (CWE)

The CWE is a comprehensive category system for identifying software and hardware vulnerabilities and weaknesses, encompassing over 600 categories. Examples of hardware-related weaknesses include:

- Memory and Storage Issues (CWE 1202): Related to weaknesses in memory (e.g., DRAM, SRAM) and storage technologies (e.g., NAND Flash).

- Manufacturing and Life Cycle Management Concerns (CWE 1195): Root-caused to defects during semiconductor manufacturing or the lifecycle and supply chain.

- Security Flow Issues (CWE 1196): Pertaining to improper design of full-system security flows, such as secure boot and secure update.

- Privilege Separation and Access Control Issues (CWE 1198): Concerning features and mechanisms that provide hardware-based isolation and access control.

Refer: https://cwe.mitre.org/data/definitions/658.html

Benefits of Secure Hardware

Securing hardware not only enhances security but also provides additional benefits:

1. Performance: Hardware solutions often offer increased performance compared to software solutions.

2. Enablement for Important Security Use Cases: Certain security use cases can only be effectively implemented through hardware solutions.

3. Cost Efficiency: Hardware solutions are more cost-effective when produced in large quantities.

Performance and Energy Efficiency Benefits:

- Speed and Performance:

  - Secure boot mechanisms provide fast authentication.

  - High communication bandwidth/packet rate.

- Energy Efficiency:

  - Crucial for battery-operated systems.

  - Reduces heat dissipation.

Examples of Hardware-Based Security Mechanisms:

- Secure Debug:Protects against unauthorized microcontroller access.

- Secure Boot/Authenticated Boot: Verifies code integrity before execution.

- Secure Flashing: Prevents flashing of malicious code through signature verification.

- Protection of Intellectual Property: Encrypts firmware with on-the-fly decryption at startup.

- Sensor/Actuator Protection: Ensures sensor/actuator authentication through challenge-response protocols.

- Authenticated Communication: Prevents message counterfeiting by adding signatures to messages.

 Trusted Execution Environment (TEE)

A Trusted Execution Environment (TEE) is a secure area within the main processor aimed at providing:

1. Execution Isolation

2. Secure Storage

3. Secure Applications

4. Authentication Verification

Five Levels of Isolation

To ensure secure hardware isolation, the following methods are employed:

1. Software Logic-Based Isolation: Prevents malicious actions from jumping between assets (e.g., processes, web pages).

2. Memory Management Unit (MMU)-Based Isolation: Splits memory into isolated regions managed by dedicated software.

3. Obfuscation: Protects against reverse engineering by making code difficult to understand.

4. Hardware-Based Isolation: Provides robust isolation through hardware mechanisms.

5. Sub-System Isolation: Isolates components with their own memory and power management.

Intel SGX (Software Guard Extensions)

Intel SGX is an instruction set for x86-based CPUs that enhances security by creating secure enclaves in memory. Key features include:

1. Splitting applications into secure and non-secure portions.

2. Creating protected enclaves at runtime.

3. Restricting external access to enclave data.

AMD SME (Secure Memory Encryption)

AMD Secure Memory Encryption (SME) is an x86 instruction set extension for encrypting memory at a page level using a single ephemeral key. Key features include:

1. Inline encryption/decryption by a hardware AES engine.

2. No application changes required.

3. Cryptographically isolates hypervisor and guest VMs.

Hardware Security Modules (HSM)

An HSM is a physical device that secures sensitive information, digital keys, certificates, and algorithms. Typical features include:

- Cryptographic accelerators in hardware.

- True Random Number Generators.

- Secure storage for cryptographic material.

- Secure execution environment.

- Mechanisms to detect/prevent attacks.

HSM Use Cases:

1. Generating secure cryptographic keys.

2. Storing cryptographic keys securely.

3. Managing keys and performing encryption/decryption processes.

By implementing these hardware security measures, organizations can achieve robust protection against a wide range of security threats, ensuring the integrity and confidentiality of sensitive data and functions.

Resources:

//https://www.nxp.com/docs/en/white-paper/Security-Subsystems-WP.pdf