secure_boot_hash_and_verify.c

// root_of_trust.c
#include "sha3/sha3.h"

/* The location and size of the bootloader in DRAM
are linked into the boot ROM image. */
extern const void * bootloader_ptr;
extern const size_t bootloader_size;

/* the expected SHA-3-512 hash is also a constant
linked into the boot ROM image */
extern const uint64_t bootloader_expected_hash[8];

bool rot_hash_and_verify() {
  /* Reserve stack space for hash of bootloader in DRAM */
  uint64_t bootloader_hash[8]; // 512-bit (64 byte) hash

  // Compute 64 Byte sha-3 hash of the trusted bootloader DRAM */
  sha3(&bootloader_ptr, bootloader_size, bootloader_hash, 64);

  /* Compare the root of trust hash againt an expected value
  (there is no private information to clean up afterward) */
  for (unsigned int i=0; i<8; i++) {
    if (bootloader_hash[i] != bootloader_expected_hash[i]) {
      return false;
    }
  }
  return true;
}