What are best practices for secure firmware development?

Secure firmware practices: Secure boot chain (root of trust, cryptographic verification), Encryption (data at rest and in transit, AES hardware acceleration), Key management (hardware secure storage, key derivation), Authentication (mutual authentication for communication), Secure update (signed firmware, anti-rollback), Side-channel protection (constant-time cryptography, power analysis countermeasures), Secure coding (bounds checking, input validation, no buffer overflows), Debug protection (disable JTAG in production, secure debug authentication), and Secure development process (threat modeling, code review, penetration testing). Utilize hardware security features: TrustZone, secure boot ROM, hardware RNG.