How do SoCs implement secure boot and trusted execution environments (TEE)?
Modern System-on-Chip ( SoC ) designs implement secure boot and Trusted Execution Environments (TEEs) to protect against firmware tampering, unauthorized code execution, and side-channel attacks. Here’s how they work: 1. Secure Boot Purpose: Ensures only authenticated code runs during boot. Implementation Steps: a. Boot ROM (Immutable Root-of-Trust) Hard-coded in silicon, executes first. Verifies the digital signature of the next bootloader stage (e.g., First-Stage Bootloader (FSBL) ). Uses asymmetric cryptography (e.g., RSA/ECDSA) or symmetric keys (e.g., HMAC). b. Chain of Trust Each subsequent stage (bootloader, OS kernel) is cryptographically verified before execution. Example: ARM Trusted Firmware (TF-A) verifies U-Boot. U-Boot verifies the Linux kernel. c. Anti-Rollback Protection SoCs store a security version number (SVN) in eFuses. Prevents downgrading to older, vulnerab...