Append appropriate
PASSWORD
(SEC_ZONEx_UNENC_PWD)
to the payload at the end of the
PAYLOAD
Update
firmware or data
(PAYLOAD)
PASSWORD
Update
firmware or data
(PAYLOAD)
Device Security
278
SLAU356I – March 2015 – Revised June 2019
Copyright © 2015–2019, Texas Instruments Incorporated
System Controller (SYSCTL)
The user can choose between an encrypted update (AES256-CBC enc 128-bit password
authenticated) or unencrypted update (authenticated by a 128-bit password) for a particular IP protected
secure zone. The use of an encrypted or unencrypted update is controlled by the user securing the IP
protected zone at the time of IP protection setup. IP protected secure zones configured with unencrypted
updates can be updated using unencrypted update only. Similarly, IP protected secure zones configured
with encrypted updates can be updated using the Encrypted update only.
4.8.5.4.1 Unencrypted Update: IP Protected Device
The unencrypted update of an IP protected secure zone uses a password-based mechanism to ensure
that a valid user is trying to update a secure area. To use this mode, first append the 128-bit password to
the end of the data to be updated (see
).
Figure 4-3. Data Setup for IP Protected Secure Zone Unencrypted Update
The password used here should be the same as SEC_ZONEx_UNENC_PWD provided when setting up
the IP protected secure zone and is different from the BSL password. The payload is now transmitted
through BSL into a free space in Bank 1 of the device main flash memory.
This is followed by a boot override into the design with the command SEC_ZONEx_UPDATE. See
for details on boot-overrides.
The device boot code now finds a boot override command. Boot code checks for the authenticity by
comparing the SEC_ZONEx_UNENC_PWD from the payload against the values that were provided during
IP Protected secure zone setup and then performs the update if the passwords match. The status of the
update is indicated in the ACK field of the specific command in the boot override mailbox.
4.8.5.4.2 Encrypted Update: IP Protected Device
The encrypted update of an IP protected secure zone is similar to the encrypted update of a device with
JTAG and SWD lock enabled.
A data setup phase is needed prior to use of the Encrypted update. This is shown in
. The
password shown here should be the same as the password used when enabling the IP Protected secure
zone in the boot override mailbox (SEC_ZONEx_UNENC_PWD). This password is first appended to the
end of the firmware or data to be updated and then taken through an AES-CBC encryption. The encrypted
payload is now transmitted through BSL into a free space in Bank 1 of the device main flash memory.
This is followed by a boot override into the design with the command SEC_ZONEx_UPDATE. See
for details on boot overrides.
The device boot code now finds a boot override command. Boot code decrypts the encrypted packet and
checks for the authenticity by comparing the SEC_ZONEx_UNENC_PWD from the decrypted packet
against the value that were provided during IP Protected secure zone setup and then performs the update
if the passwords match. The status of the update is indicated in the ACK field of the specific command in
the boot override mailbox.
4.8.6 Boot-Overrides
Applications running on MSP432P4xx devices can initiate boot-overrides into the system. Boot-overrides
are special boot modes in the system, where application can send a command to the device boot-code.
The following are the main uses of boot-overrides:
•
Setting up device JTAG and SWD lock.