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Hardware Security Module

Overview⚓︎

At this design stage the module is mounted and verified to be functional. The HSM could be used for e.g. secure boot and key storage.

Typical Use Cases for HSM Module with U-Boot and Yocto Linux System⚓︎

An HSM (Hardware Security Module) integrated into a Yocto Linux system with U-Boot can provide various security features, such as:

1. Secure Boot⚓︎

  • Use case: Ensure that the system boots only from a trusted source, preventing unauthorized firmware or OS from being loaded.
  • How it works: U-Boot uses the HSM to validate the digital signatures of the bootloader, kernel, and device tree during the boot process. The HSM stores the root of trust, ensuring only authenticated code is executed.

2. Cryptographic Key Management⚓︎

  • Use case: Securely generate, store, and manage cryptographic keys for applications, system components, or communication.
  • How it works: The HSM securely stores private keys, which can be used for encryption/decryption operations, such as TLS/SSL or VPN. Keys never leave the HSM, reducing the risk of compromise.

3. Encrypted Storage⚓︎

  • Use case: Protect sensitive data stored on the device, such as user credentials or encryption keys, from unauthorized access.
  • How it works: The HSM is used to manage encryption keys for encrypting/decrypting data stored in the filesystem. The kernel or applications running in userspace access data only after the proper decryption keys are provided by the HSM.

4. Digital Signatures⚓︎

  • Use case: Ensure data integrity and authenticity by signing or verifying signatures of files, logs, or messages.
  • How it works: The HSM performs digital signing or verification operations using secure private keys, such as signing a software update package or verifying a message's authenticity in secure communication protocols.

5. Secure Firmware Updates⚓︎

  • Use case: Safeguard the firmware update process against tampering or malicious alterations.
  • How it works: Before applying an update, U-Boot and the operating system verify the integrity and authenticity of the firmware by using keys stored in the HSM. This ensures the firmware is from a trusted source and hasn’t been altered.

6. Public Key Infrastructure (PKI) Integration⚓︎

  • Use case: Facilitate secure device authentication and secure communication in a network of IoT devices.
  • How it works: The HSM manages public and private key pairs for device identification. It can be used to authenticate the device to a network, ensuring secure communication via protocols like SSH, TLS, or secure MQTT.

7. Random Number Generation⚓︎

  • Use case: Provide high-quality, hardware-based random numbers for cryptographic operations.
  • How it works: The HSM's secure random number generator can be used for generating keys, nonces, or other cryptographic values needed by the operating system for secure operations.

8. Secure Networking (TLS/SSL)⚓︎

  • Use case: Secure communications between the device and external services via encrypted channels.
  • How it works: The HSM provides key storage and cryptographic operations needed to establish and manage TLS/SSL connections. The keys used for authentication and encryption are stored in the HSM, reducing the risk of key theft.