How to Enable Hardware Crypto on STM32H750VBT6 : A Comprehensive Tutorial

The STM32H750VBT6 microcontroller is designed to deliver outstanding performance, and one of its Power ful features is its ability to offload cryptographic tasks to specialized hardware. Enabling hardware cryptography on this microcontroller can drastically improve the efficiency of security operations and offer significant performance improvements over software-based encryption. In this first part of the tutorial, we will explore the importance of hardware cryptography and outline the setup steps required to enable and configure cryptographic functions on the STM32H750VBT6.

Understanding Hardware Cryptography

In embedded systems, cryptography plays a crucial role in ensuring data security, confidentiality, and integrity. Hardware cryptographic module s, like the ones found in the STM32H750VBT6, are designed to accelerate cryptographic processes and reduce the CPU load by performing encryption, decryption, and key Management operations directly in hardware. This enables systems to achieve higher throughput and faster response times compared to purely software-based implementations.

STM32H750VBT6 comes equipped with a dedicated hardware crypto engine capable of supporting several cryptographic algorithms, such as AES, RSA, SHA, and HMAC. These hardware accelerators are optimized for speed, energy efficiency, and secure key handling, making them an ideal choice for applications in security-sensitive fields like IoT devices, automotive systems, and industrial control systems.

Why Use Hardware Crypto?

Enabling hardware-based cryptography offers numerous advantages for embedded systems:

Performance Improvement: Hardware accelerators are specifically designed to perform cryptographic operations faster than general-purpose processors, which translates into significant performance gains, especially in applications requiring real-time encryption and decryption.

Reduced Power Consumption: Hardware crypto modules are optimized to perform cryptographic tasks with minimal power consumption. This makes them perfect for battery-powered or low-power devices, where energy efficiency is essential.

Security Enhancements: By using hardware-based cryptography, you can ensure better protection against side-channel attacks, reverse engineering, and other security vulnerabilities. The keys are securely stored in hardware, preventing unauthorized Access .

Offloading CPU: By offloading cryptographic operations to the hardware engine, the microcontroller’s CPU can focus on other tasks, improving the overall system’s efficiency.

STM32H750VBT6 Hardware Crypto Features

The STM32H750VBT6 microcontroller is part of the STM32H7 series, which features a rich set of peripherals, including the integrated hardware crypto engine. Here’s a quick overview of the key cryptographic features available:

AES (Advanced Encryption Standard): A widely used symmetric encryption algorithm for securing data. The STM32H750VBT6 supports AES encryption and decryption with key sizes of 128, 192, and 256 bits.

RSA: An asymmetric encryption algorithm used for secure data transmission. RSA is supported for both encryption and signature verification.

SHA (Secure Hash Algorithm): A family of cryptographic hash functions, including SHA-1, SHA-224, SHA-256, SHA-384, and SHA-512, which are essential for ensuring data integrity.

HMAC (Hash-Based Message Authentication Code): Used to verify data authenticity by combining a cryptographic hash function and a secret key.

Random Number Generation: A true random number generator (TRNG) is also available to produce high-quality random numbers for cryptographic operations.

Setting Up the Development Environment

Before diving into the hardware crypto configuration, you’ll need to set up the STM32 development environment. The STM32CubeMX tool is highly recommended for configuring the STM32H750VBT6 microcontroller and generating the initialization code.

Step 1: Download and Install STM32CubeMX

STM32CubeMX is a graphical configuration tool provided by STMicroelectronics to simplify microcontroller setup. It allows you to easily configure peripherals, including the hardware crypto engine, and generates the necessary initialization code.

Visit the STMicroelectronics website to download the latest version of STM32CubeMX.

Install the software following the instructions provided.

Step 2: Create a New Project

Once STM32CubeMX is installed, launch the application and follow these steps to create a new project for the STM32H750VBT6:

Click on "New Project."

Select the STM32H750VBT6 microcontroller from the list or use the part number search feature.

Choose the correct board if you are using a development board.

Set up the project settings (e.g., project name, toolchain).

Step 3: Enable Hardware Crypto Features

Now that your project is created, it's time to enable the cryptographic features of the STM32H750VBT6.

In the STM32CubeMX interface , navigate to the "Peripherals" section.

Locate the "Crypto" section under the “Middleware” tab and enable the "Hardware Crypto" option.

Enable the cryptographic algorithms you intend to use. For example, if you plan to use AES encryption, select the AES module. For RSA, enable the RSA module.

Set up any additional options, such as the key size, operation modes (encryption or decryption), or hash algorithms.

Step 4: Generate Code

Once the hardware crypto modules are enabled, you can generate the initialization code for your project. This step will configure the microcontroller’s hardware and prepare the codebase for use with the selected cryptographic features.

Click "Project" in STM32CubeMX.

Choose your IDE (e.g., KEIL, STM32CubeIDE).

Click "Generate Code."

With the code generated, you can now move on to configuring the cryptographic algorithms and incorporating them into your application.

Now that the hardware crypto engine is enabled, it’s time to dive into using the cryptographic features in your application. In this part of the tutorial, we’ll cover how to write the code to perform various cryptographic operations, such as AES encryption, SHA hashing, and RSA key generation. We’ll also touch on some optimization techniques and best practices for working with the hardware crypto engine.

Using the Hardware Crypto Engine

The STM32H750VBT6’s hardware crypto engine is easily accessible through the HAL (Hardware Abstraction Layer) libraries, which provide convenient functions to configure and use the cryptographic modules. Let’s look at how you can use these functions to implement common cryptographic operations.

AES Encryption and Decryption

AES is one of the most commonly used symmetric encryption algorithms, and the STM32H750VBT6 makes it easy to implement AES encryption in hardware. Here’s an example of how to perform AES encryption using the hardware crypto engine:

#include "crypto.h"

HAL_CRYP_Encrypt(&hcryp, inputData, inputSize, outputData, timeout);

In this code snippet:

hcryp is the handle for the CRYP peripheral (the hardware crypto engine).

inputData is the data to be encrypted.

inputSize is the size of the input data.

outputData is where the encrypted data will be stored.

timeout is the maximum time the operation should take.

You can also perform AES decryption by using the HAL_CRYP_Decrypt function.

SHA Hashing

The STM32H750VBT6 supports various SHA algorithms, such as SHA-256. To perform SHA hashing, you can use the following code:

HAL_CRYP_SHA256_Start(&hcryp, inputData, inputSize, outputHash, timeout);

This function computes the SHA-256 hash of the input data and stores the result in outputHash.

RSA Encryption and Signature

RSA encryption and digital signatures are essential for secure communication. The STM32H750VBT6 supports RSA key generation, encryption, and signature verification.

To generate RSA keys, use the following function:

HAL_CRYP_RSA_GenerateKeys(&hcryp, &publicKey, &privateKey);

For RSA encryption or signature verification, you would use the respective functions to encrypt data or verify signatures.

Optimizing Performance

To maximize the performance of the hardware crypto engine, you can follow these best practices:

Minimize Interrupts: Hardware crypto operations should be executed with minimal interruption. If possible, disable interrupts while performing crypto operations to avoid context switches.

Use DMA (Direct Memory Access): The STM32H750VBT6 supports DMA for fast data transfer. Using DMA with the crypto engine can significantly improve throughput and reduce CPU load.

Key Management: Ensure that cryptographic keys are managed securely. Store sensitive keys in secure memory and avoid exposing them in software.

Conclusion

Enabling hardware cryptography on the STM32H750VBT6 can dramatically improve the performance and security of embedded systems. By using the hardware crypto engine, developers can offload cryptographic tasks from the CPU, enhance system security, and achieve better performance in resource-constrained environments. By following the steps outlined in this tutorial, you can easily integrate cryptographic operations into your application and leverage the full potential of the STM32H750VBT6 microcontroller.

With hardware acceleration at your fingertips, the possibilities for creating secure and efficient embedded applications are limitless.