Introduction
This document describes the debug authentication (DA) security service. When not specified, STM32 refers to all applicable
products present in Table 1. Applicable products.
The STM32 debug authentication controls the product life cycle, such as regressions (for more details about the life cycle, refer
to the reference manual), and debug reopening:
• Regression
The user leverages the regression service to erase the user firmware and data within the user flash memory, SRAM, and
option-byte keys (OBK) when OBK are supported by STM32. After a regression, STM32 falls back in product state open.
Depending on STM32 products, there can be several kinds of regression: full regression and partial regression Refer to
Section 3: STM32 debug authentication services description for more details.
• Debug reopening
The user leverages the debug reopening to safely reopen the debug on STM32 when it is in a product state different than
open.
When the STM32 product state is not open, the user can trigger the debug authentication services by sending a password or a
certificate chain to the STM32 device.
These two options are named the debug authentication methods.
The debug authentication protocol uses the STM32 device debug access port 0 (DAP0) and the DBGMCU IP for
communication.
Figure 1. Debug authentication interface
DT73818V1
STM32
Probe
Debug port
/ DBGMCU
Debug
Authentication
The STM32 debug authentication implements the Arm
®
PSA ADAC (authenticated debug access control) specification.
The Arm
®
PSA ADAC protocol is based on the certificate chain and the challenge/response principle.
Table 1. Applicable products
Type Product
Microcontrollers STM32H5 series, STM32H7R3/7S3, STM32H7R7/7S7 lines
Getting started with debug authentication (DA) for STM32 MCUs
AN6008
Application note
AN6008 - Rev 2 - May 2024
For further information contact your local STMicroelectronics sales office.
www.st.com
1 General information
This document applies to
•
STM32H5 series Arm
®
Cortex
®
‑M33‑based microcontrollers.
• STM32H7Rx/7Sx Arm
®
Cortex
®
M7 based microcontrollers.
Note: Arm is a registered trademark of Arm Limited (or its subsidiaries) in the US and/or elsewhere.
Table 2. Terms and abbreviations
Acronym Definition
AES Advanced encryption standard
ADAC Authenticated debug access control
DA Debug authentication
EPOCH Epoch
HDP Hidden protection
HDPL Hidden protection level
iRoT Immutable root of trust
JTAG Joint test action group
OBK Option-byte keys
OFTDEC On-the-fly decryption
PKA Public key accelerator
PSA Platform security architecture
SAES Secure advanced encryption standard
SoC System on chip
SDM Secure debug manager
STiRoT ST immutable root of trust
SWD Serial wire debug
TZ
Arm
®
TrustZone
®
TZEN
Arm
®
TrustZone
®
enabled
uRoT Updatable root of trust
WRP Write protection
Reference documents
Reference
Name/address Title
[1] DEN 0101
Authenticated Debug Access Control 1.0
(1)
[2] RM0481 STM32H573/56x & STM32H533/523 reference manual
[3] RM0492 STM32H503 reference manual
[4] AN6007 Application note for STiRoT
[5]
Security features on
STM32H5 MCUs
https://wiki.st.com/stm32mcu/wiki/Security:Security_features_on_STM32H5_MCUs
[6] RM0477 STM32H7Rx/7Sx reference manual
AN6008
General information
AN6008 - Rev 2
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