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Raspberry Pi 5 - secure boot

This directory contains the beta bootcode5.bin (recovery.bin) and a pre-release pieeprom.bin bootloader release. Older bootloader and recovery.bin releases do not support secure boot.

Required packages

sudo apt install xxd python3-pycryptodome

Optional. Specify the private key file in an environment variable.

Alternatively, specify the path when invoking the helper scripts.

export KEY_FILE="${HOME}/private.pem"

Optional. Customize the EEPROM config.

Custom with the desired bootloader settings. See: Bootloader configuration

Setting SIGNED_BOOT=1 enables signed-boot mode so that the bootloader will only boot.img files signed with the specified RSA key. Since this is an EEPROM config option secure-boot can be tested and reverted via RPIBOOT at this stage.

Sign the EEPROM and the second stage bootloader

The BCM2712 boot ROM requires the second stage firmware (recovery.bin / bootcode5.bin) to be counter-signed with the customer private key in secure-mode. Pass the f flag to enable firmware counter-signing.

../tools/update-pieeprom.sh -f -k "${KEY_FILE}"

If secure-boot has already been enabled on the device then recovery.bin must then also be counter-signed. However, booting a counter-signed recovery.bin image on a fresh board without secure-boot enabled will fail because the ROM is effectively checking this against a key hash of zero.

../tools/update-pieeprom.sh -fr -k "${KEY_FILE}"

pieeprom.bin can then be flashed to the bootloader EEPROM via rpiboot.

Program the EEPROM image using rpiboot

  • Power off DUT
  • Set nRPIBOOT jumper (or hold power button before power on) and remove EEPROM WP protection
cd secure-boot-recovery5
../rpiboot -d .
  • Power ON the DUT

Locking secure-boot mode

After verifying that the signed OS image boots successfully the system can be locked into secure-boot mode. This writes the hash of the customer public key to "one time programmable" (OTP) bits. From then onwards:

  • The 2712 boot ROM verifies that the secondstage firmware (recovery.bin / bootsys) are signed with the customer private key in addition to the Raspberry Pi private key.
  • The bootloader will only load OS images signed with the customer private key.
  • The EEPROM configuration file must be signed with the customer private key.
  • It is not possible to downgrade to an old version of the bootloader that doesn't support secure boot.
  • BETA bootloader releases are not signed with the ROM secure boot key and will not boot on a system where revoke_devkey has been set.

WARNING: Modifications to OTP are irreversible. Once revoke_devkey has been set it is not possible to unlock secure-boot mode or use a different private key.

To enable this edit the config.txt file in this directory and set program_pubkey=1

  • program_pubkey - If 1, write the hash of the customer's public key to OTP.

Revoking the dev key - NOT SUPPORTED YET

  • revoke_devkey - If 1, revoke the ROM bootloader development key which requires secure-boot mode and prevents downgrades to bootloader versions that don't support secure boot.

Disabling VideoCore JTAG

VideoCore JTAG may be permanently disabled by setting program_jtag_lock in config.txt. This option has no effect unless the public key hash (program_pubkey) has been successfully programmed.

See config.txt