Integrate TPM 2.0 for Secure Boot and DICE on STM32 with Mbed TLS

Introduction

Integrating a TPM 2.0 chip with STM32 microcontrollers enhances the security of embedded systems by enabling secure boot processes and DICE (Dynamic Integrity Measurement Architecture) provisioning. This tutorial guides you through the steps required to set up and integrate a TPM 2.0 chip using Mbed TLS.

Prerequisites

• Basic knowledge of embedded systems and STM32 programming
• Familiarity with C programming language
• STM32 development board (e.g., STM32F4 series)
• TPM 2.0 chip compatible with your STM32 board
• Mbed TLS library
• Development environment set up (e.g., STM32CubeIDE)
• Hardware connections (wires, breadboard, etc.)

Parts/Tools

• STM32 development board
• TPM 2.0 chip (e.g., Infineon OPTIGA™ TPM)
• Mbed TLS library
• STM32CubeIDE or another IDE
• USB programmer/debugger
• Connecting wires

Steps

1. Set up your development environment
   • Install STM32CubeIDE and set up your STM32 development board.
   • Download and integrate the Mbed TLS library into your project.
2. Connect the TPM 2.0 chip
   • Identify the pins of the TPM chip and connect them to the STM32 board.
   • Common connections include:

     
                         TPM Pin   STM32 Pin
                         --------   ----------
                         SCL        I2C_SCL
                         SDA        I2C_SDA
                         GND        GND
                         VCC        3.3V
                     

3. Initialize the Mbed TLS library
   • Include the necessary headers in your source code:

   
                   #include "mbedtls/platform.h"
                   #include "mbedtls/tss.h"
               

   • Initialize Mbed TLS in your main function:

   
                   mbedtls_platform_context ctx;
                   mbedtls_platform_setup(&ctx);
               

4. Configure the TPM for secure boot
   • Use Mbed TLS to create a secure boot key pair:

   
                   mbedtls_tss_context tss;
                   mbedtls_tss_init(&tss);
                   mbedtls_tss_create_keypair(&tss, key, &public_key);
               

   • Store the key securely in the TPM.
5. Provision DICE
   • Use Mbed TLS to establish a secure channel with the TPM:

   
                   mbedtls_tss_create_session(&tss, session);
                   mbedtls_tss_open_session(&session);
               

   • Provision the DICE by measuring the integrity of the boot firmware.

Troubleshooting

• Issue: TPM not detected by STM32
• Check the wiring connections between the TPM and STM32.
• Ensure that the I2C interface is correctly configured in your STM32 project.
• Issue: Mbed TLS initialization failures
• Verify that the Mbed TLS library is correctly integrated into your project.
• Check for any missing dependencies or header files.
• Issue: Secure boot key pair creation fails
• Make sure the TPM is properly powered and configured.
• Review the Mbed TLS configuration settings for any discrepancies.

Conclusion

Integrating a TPM 2.0 chip with an STM32 microcontroller using Mbed TLS significantly enhances the security of your embedded applications. By following the steps outlined in this tutorial, you can successfully set up secure boot and provision DICE to ensure integrity and security. Continue exploring advanced features and configurations to further strengthen your application security.