OPTIGA™: Cryptography

This example uses an OPTIGA™ Trust M v3 secure element on a PSOC™ 6 MCU to execute example code to perform available crypto operations on the secure element. This example outputs the result and the time taken to perform the crypto operations in a UART terminal.

View this README on GitHub.

Provide feedback on this code example.

Requirements

• ModusToolbox™ v3.1 or later (tested with v3.1)
• Board support package (BSP) minimum required version: 4.0.0
• Programming language: C
• Associated parts:
  • All PSOC™ 6 MCU parts
  • OPTIGA™ Trust M v3

Supported toolchains (make variable 'TOOLCHAIN')

• GNU Arm® Embedded Compiler v11.3.1 (GCC_ARM) - Default value of TOOLCHAIN
• Arm® Compiler v6.16 (ARM)
• IAR C/C++ Compiler v9.30.1 (IAR)

Supported kits (make variable 'TARGET')

• Rapid IoT connect Developer Kit (CYSBSYSKIT-DEV-01) - Default value of TARGET
• PSOC™ 62S2 Evaluation Kit (CY8CEVAL-062S2, CY8CEVAL-062S2-LAI-43439M2, CY8CEVAL-062S2-LAI-4373M2, CY8CEVAL-062S2-MUR-43439M2, CY8CEVAL-062S2-MUR-4373EM2)
• PSOC™ 62S2 Pioneer Kit in combination with OPTIGA™ Trust Adapter (CY8CKIT-062S2-43012)

To use this code example on different hardware, follow this guide. To use kits which are based on the OPTIGA™ Trust M Express or OPTIGA™ Trust M MTR Shields, read the Enabling the Shielded Connection Section carefully.

Hardware setup

This example uses the board's default configuration for all the supported kits except CY8CKIT-062S2-43012. This kit requires the OPTIGA™ Trust Adapter and any OPTIGA™ Trust M Shield (e.g. OPTIGA™ Trust M Express or OPTIGA™ Trust M MTR) to be plugged on it. See the kit user guide to ensure that the board is configured correctly

Software setup

See the ModusToolbox™ tools package installation guide for information about installing and configuring the tools package.

Install a terminal emulator if you don't have one. Instructions in this document use Tera Term.

Enabling the shielded connection

By default, the shielded connection (encrypted communication over I2C) is disabled to improve the out-of-the-box experience. However, the security of some examples would benefit from having the shielded connection enabled.

The shielded connection requires a shared "Platform Binding Secret" (PBS) on the Host MCU and the OPTIGA™ Trust M, which will be used for a session-based key-derivation and following encryption of the I2C. Read more here

The shielded connection can be enabled by uncommenting the macro #define OPTIGA_COMMS_SHIELDED_CONNECTION in optiga_lib_config_mtb.h.

The OPTIGA™ Trust M (v3) comes without a pre-provisioned PBS, meaning it can generate one at runtime and work out-of-the-box with this example.

OPTIGA™ Trust M Express and OPTIGA™ Trust M MTR come with a pre-provisioned PBS. This PBS must also be known to the host if the shielded connection will be used. If you want to use it in combination with OPTIGA™ Trust M Express or MTR chips, remember to set the matching secret uint8_t optiga_platform_binding_shared_secret in COMPONENT_OPTIGA_CYHAL/pal_os_datastore.c. If some examples report a failure with error code 0x0107 this is due to a non-matching PBS on the host and OPTIGA™ Trust M.

Using the code example

Create the project

The ModusToolbox™ tools package provides the Project Creator as both a GUI tool and a command line tool.

Use Project Creator GUI

1. Open the Project Creator GUI tool.

   There are several ways to do this, including launching it from the dashboard or from inside the Eclipse IDE. For more details, see the Project Creator user guide (locally available at {ModusToolbox™ install directory}/tools_{version}/project-creator/docs/project-creator.pdf).

2. On the Choose Board Support Package (BSP) page, select a kit supported by this code example. See Supported kits.

   Note: To use this code example for a kit not listed here, you may need to update the source files. If the kit does not have the required resources, the application may not work.

3. On the Select Application page:

   a. Select the Applications(s) Root Path and the Target IDE.

   Note: Depending on how you open the Project Creator tool, these fields may be pre-selected for you.

   b. Select this code example from the list by enabling its check box.

   Note: You can narrow the list of displayed examples by typing in the filter box.

   c. (Optional) Change the suggested New Application Name and New BSP Name.

   d. Click Create to complete the application creation process.

Use Project Creator CLI

The 'project-creator-cli' tool can be used to create applications from a CLI terminal or from within batch files or shell scripts. This tool is available in the {ModusToolbox™ install directory}/tools_{version}/project-creator/ directory.

Use a CLI terminal to invoke the 'project-creator-cli' tool. On Windows, use the command-line 'modus-shell' program provided in the ModusToolbox™ installation instead of a standard Windows command-line application. This shell provides access to all ModusToolbox™ tools. You can access it by typing "modus-shell" in the search box in the Windows menu. In Linux and macOS, you can use any terminal application.

The following example clones the "mtb-example-optiga-crypto" application with the desired name "OptigaCrypto" configured for the CYSBSYSKIT-DEV-01 BSP into the specified working directory, C:/mtb_projects:

project-creator-cli --board-id CYSBSYSKIT-DEV-01 --app-id mtb-example-optiga-crypto --user-app-name OptigaCrypto --target-dir "C:/mtb_projects"

The 'project-creator-cli' tool has the following arguments:

Argument	Description	Required/optional
--board-id	Defined in the field of the BSP manifest	Required
--app-id	Defined in the field of the CE manifest	Required
--target-dir	Specify the directory in which the application is to be created if you prefer not to use the default current working directory	Optional
--user-app-name	Specify the name of the application if you prefer to have a name other than the example's default name	Optional

Note: The project-creator-cli tool uses the git clone and make getlibs commands to fetch the repository and import the required libraries. For details, see the "Project creator tools" section of the ModusToolbox™ tools package user guide (locally available at {ModusToolbox™ install directory}/docs_{version}/mtb_user_guide.pdf).

Open the project

After the project has been created, you can open it in your preferred development environment.

Eclipse IDE

If you opened the Project Creator tool from the included Eclipse IDE, the project will open in Eclipse automatically.

For more details, see the Eclipse IDE for ModusToolbox™ user guide (locally available at {ModusToolbox™ install directory}/docs_{version}/mt_ide_user_guide.pdf).

Visual Studio (VS) Code

Launch VS Code manually, and then open the generated {project-name}.code-workspace file located in the project directory.

For more details, see the Visual Studio Code for ModusToolbox™ user guide (locally available at {ModusToolbox™ install directory}/docs_{version}/mt_vscode_user_guide.pdf).

Keil µVision

Double-click the generated {project-name}.cprj file to launch the Keil µVision IDE.

For more details, see the Keil µVision for ModusToolbox™ user guide (locally available at {ModusToolbox™ install directory}/docs_{version}/mt_uvision_user_guide.pdf).

IAR Embedded Workbench

Open IAR Embedded Workbench manually, and create a new project. Then select the generated {project-name}.ipcf file located in the project directory.

For more details, see the IAR Embedded Workbench for ModusToolbox™ user guide (locally available at {ModusToolbox™ install directory}/docs_{version}/mt_iar_user_guide.pdf).

Command line

If you prefer to use the CLI, open the appropriate terminal, and navigate to the project directory. On Windows, use the command-line 'modus-shell' program; on Linux and macOS, you can use any terminal application. From there, you can run various make commands.

For more details, see the ModusToolbox™ tools package user guide (locally available at {ModusToolbox™ install directory}/docs_{version}/mtb_user_guide.pdf).

Operation

1. Connect the board to your PC using the provided USB cable through the KitProg3 USB connector.

2. Open a terminal program and select the KitProg3 COM port. Set the serial port parameters to 8N1 and 115200 baud.

3. Program the board using one of the following:

   Using Eclipse IDE

   1. Select the application project in the Project Explorer.

   2. In the Quick Panel, scroll down, and click <Application Name> Program (KitProg3_MiniProg4).

   In other IDEs

   Follow the instructions in your preferred IDE.

   Using CLI

   From the terminal, execute the make program command to build and program the application using the default toolchain to the default target. The default toolchain is specified in the application's Makefile but you can override this value manually:

   make program TOOLCHAIN=<toolchain>
   

   Example:

   make program TOOLCHAIN=GCC_ARM
   

4. After programming, the application starts automatically. Confirm that the following examples are displayed on the UART terminal.

   Figure 1. Terminal output on program startup

   

Debugging

You can debug the example to step through the code.

In Eclipse IDE

Use the <Application Name> Debug (KitProg3_MiniProg4) configuration in the Quick Panel. For details, see the "Program and debug" section in the Eclipse IDE for ModusToolbox™ user guide.

Note: (Only while debugging) On the CM4 CPU, some code in main() may execute before the debugger halts at the beginning of main(). This means that some code executes twice – once before the debugger stops execution, and again after the debugger resets the program counter to the beginning of main(). See KBA231071 to learn about this and for the workaround.

In other IDEs

Follow the instructions in your preferred IDE.

Design and implementation

This example initializes the OPTIGA™ Trust device by calling a dedicated function from the Platform Abstraction Layer (PAL). This function initializes all hardware- and system-relevant components. Afterwards, the example sequentially calls isolated sub-examples to showcase various API combinations.

All examples follow the same pattern init function, do_crypto function, and an optional deinit function. The following snippets provide an overview:

void example_main(void)
{
   uint8_t random_data_buffer [32];
   optiga_crypt_t * me_crypt_instance = NULL;
   optiga_lib_status_t return_status = !OPTIGA_LIB_SUCCESS;

   do
   {
      /*
      * Step 1. Initialize the OPTIGA device
      */
      example_optiga_init();

      /*
      * Step 2. Create an instance of optiga_crypt to perform any crypto operation on the OPTIGA device.
      */
      me_crypt_instance = optiga_crypt_create(0, optiga_lib_callback, NULL);
      if (NULL == me_crypt_instance)
      {
            break;
      }

      /*
      * Step 3..n-1. Perform any operation with the OPTIGA device; e.g., get a true random number.
      * random_data_buffer should contain the resulting random number.
      */
      optiga_lib_status = OPTIGA_LIB_BUSY;
      return_status = optiga_crypt_random(me_crypt_instance,
                                          OPTIGA_RNG_TYPE_TRNG,
                                          random_data_buffer,
                                          sizeof(random_data_buffer));

      WAIT_AND_CHECK_STATUS(return_status, optiga_lib_status);

      /* Step n. De-initialize the OPTIGA device. This step is optional in many cases because some resources on MCU-based systems cannot be de-initialized.
      */
      example_optiga_deinit();
   } while (FALSE);
}

OPTIGA™ init and deinit functions simply allocate a new command context and send an OpenApplication command to the chip. The while loop is required to synchronize the state machine. The application is free to implement this differently and check the status occasionally; the rest might be in an idle state.

#include "optiga/optiga_crypt.h"
#include "optiga/optiga_util.h"
#include "optiga/optiga_lib_config.h"


optiga_util_t * me_util_instance = NULL;
optiga_crypt_t * me_crypt_instance = NULL;

/**
 * Callback when optiga_util_xxxx operation is completed asynchronously
 */
static volatile optiga_lib_status_t optiga_lib_status;
//lint --e{818} suppress "argument "context" is not used in the sample provided"
static void optiga_lib_callback(void * context, optiga_lib_status_t return_status)
{
   optiga_lib_status = return_status;
   if (NULL != context)
   {
      // callback to upper layer here
   }
}

// Check return status
#define WAIT_AND_CHECK_STATUS(return_status, optiga_lib_status)\
                            if (OPTIGA_LIB_SUCCESS != return_status)\
                            {\
                                break;\
                            }\
                            while (OPTIGA_LIB_BUSY == optiga_lib_status)\
                            { }\
                            if (OPTIGA_LIB_SUCCESS != optiga_lib_status)\
                            {\
                                return_status = optiga_lib_status;\
                                break;\
                            }

void example_optiga_init(void)
{
    optiga_lib_status_t return_status = !OPTIGA_LIB_SUCCESS;

    do
    {
        if (NULL == me_util_instance)
        {
           /*
           Create an instance of optiga_util to open the application on the OPTIGA device.
           */
           me_util_instance = optiga_util_create(0, optiga_lib_callback, NULL);
           if (NULL == me_util_instance)
           {
               break;
           }
        }

        /**
         * Open the application on the OPTIGA device which is a precondition to perform any other operations
         * using the optiga_util_open_application.
         */
        optiga_lib_status = OPTIGA_LIB_BUSY;
        return_status = optiga_util_open_application(me_util_instance, 0);

        WAIT_AND_CHECK_STATUS(return_status, optiga_lib_status);

    }while(FALSE);
}

void example_optiga_deinit(void)
{
    optiga_lib_status_t return_status = !OPTIGA_LIB_SUCCESS;

    do
    {
        /**
         * Close the application on the OPTIGA device after all the operations are executed
         * using optiga_util_close_application.
         */
        optiga_lib_status = OPTIGA_LIB_BUSY;
        return_status = optiga_util_close_application(me_util_instance, 0);

        WAIT_AND_CHECK_STATUS(return_status, optiga_lib_status);

        // Destroy util and crypt instances
        optiga_util_destroy(me_util_instance);
        me_util_instance = NULL;
    }while(FALSE);
}

Resources and settings

Table 1: OPTIGA™ Trust M pins and their default-assigned GPIOs

OPTIGA™ Trust M pins	Assigned GPIOs by default	Notes
I2C SDA (I/O)	CYBSP_TRUSTM_I2C_SDA	Any GPIO connected to the I2C SDA line can be used
I2C SCL (Clock)	CYBSP_TRUSTM_I2C_SCL	Any GPIO connected to the I2C SDA line can be used
RST (Reset)	CYBSP_TRUSTM_RST	An optional control pin if defined in optiga_lib_config_mtb.h
VDD (Power control)	(Optional) CYBSP_TRUSTM_VDD	An optional control pin if defined in optiga_lib_config_mtb.h

Table 2: Description of optiga_lib_config_mtb.h macros

optiga_lib_config_mtb.h macros	Description	Default value
OPTIGA_CRYPT_XXXX	Controls whether to enable or disable the selected crypto support on the host library side	All enabled
OPTIGA_COMMS_SHIELDED_CONNECTION, OPTIGA_COMMS_DEFAULT_PROTECTION_LEVEL	Together define whether to use the shielded connection (encrypted and integrity-protected I2C communication) and the extent of its usage	Defined
OPTIGA_COMMS_SHIELDED_CONNECTION	If this and the OPTIGA_COMMS_DEFAULT_PROTECTION_LEVEL macro are set to OPTIGA_COMMS_NO_PROTECTION, the user must decide the API to protect and the extent of protection right before that API is called by calling OPTIGA_CRYPT_SET_COMMS_PROTECTION_LEVEL() and OPTIGA_CRYPT_SET_COMMS_PROTOCOL_VERSION()	OPTIGA_COMMS_SHIELDED_CONNECTION: Defined OPTIGA_COMMS_DEFAULT_PROTECTION_LEVEL: Set to OPTIGA_COMMS_NO_PROTECTION
OPTIGA_COMMS_DEFAULT_RESET_TYPE	The reset type if VDD or RST pin is defined. Choose 1 or 2 depending on the combination used. VDD can be used in certain cases as a reset line, but it is recommended to use them separately.	2
OPTIGA_CMD_MAX_REGISTRATIONS	Controls the number of crypt or util registrations allowed. In a very basic scenario, this can be reduced to 2 (one registration each for crypt and util).	6
OPTIGA_MAX_COMMS_BUFFER_SIZE	Maximum buffer size that the command layer should be able to store intermediately	0x615
OPTIGA_LIB_ENABLE_LOGGING	Controls whether logging can be enabled in general	Defined
OPTIGA_LIB_ENABLE_UTIL_LOGGING	If defined together with OPTIGA_LIB_ENABLE_LOGGING, outputs messages relevant to the util API	Undefined
OPTIGA_LIB_ENABLE_CRYPT_LOGGING	If defined together with OPTIGA_LIB_ENABLE_LOGGING, outputs messages relevant to the crypt API	Undefined
OPTIGA_LIB_ENABLE_CMD_LOGGING	If defined together with OPTIGA_LIB_ENABLE_LOGGING, outputs the application protocol data unit (APDU) sent to the OPTIGA™ Trust M external interface (See the solution reference manual)	Undefined
OPTIGA_LIB_ENABLE_COMMS_LOGGING	If defined together with OPTIGA_LIB_ENABLE_LOGGING, prints out I2C frames	Undefined

Related resources

Resources	Links
Application notes	AN228571 – Getting started with PSOC™ 6 MCU on ModusToolbox™ AN221774 – Getting started with PSOC™ 6 MCU on PSOC™ Creator AN210781 – Getting started with PSOC™ 6 MCU with Bluetooth® Low Energy connectivity on PSOC™ Creator AN215656 – PSOC™ 6 MCU: Dual-CPU system design
Code examples	Using ModusToolbox™ on GitHub
Device documentation	PSOC™ 6 MCU datasheets PSOC™ 6 technical reference manuals OPTIGA™ Trust M datasheets
Development kits	Select your kits from the Evaluation Board Finder page.
Libraries on GitHub	mtb-pdl-cat1 – PSOC™ 6 Peripheral Driver Library (PDL) mtb-hal-cat1 – Hardware Abstraction Layer (HAL) library retarget-io – Utility library to retarget STDIO messages to a UART port
Middleware on GitHub	optiga-trust-m – OPTIGA™ Trust M library and documents capsense – CAPSENSE™ library and documents psoc6-middleware – Links to all PSOC™ 6 MCU middleware
Tools	ModusToolbox™ – ModusToolbox™ software is a collection of easy-to-use libraries and tools enabling rapid development with Infineon MCUs for applications ranging from wireless and cloud-connected systems, edge AI/ML, embedded sense and control, to wired USB connectivity using PSOC™ Industrial/IoT MCUs, AIROC™ Wi-Fi and Bluetooth® connectivity devices, XMC™ Industrial MCUs, and EZ-USB™/EZ-PD™ wired connectivity controllers. ModusToolbox™ incorporates a comprehensive set of BSPs, HAL, libraries, configuration tools, and provides support for industry-standard IDEs to fast-track your embedded application development.

Other resources

Infineon provides a wealth of data at www.infineon.com to help you select the right device, and quickly and effectively integrate it into your design.

For PSoC™ 6 MCU devices, see How to design with PSOC™ 6 MCU - KBA223067 in the Infineon Developer Community.

Document history

Document title: CE233693 – OPTIGA™: Cryptography

Version	Description of change
1.0.0	New code example
2.0.0	Updated to support ModusToolbox™ v3.0 and BSPs v4.X
2.1.0	Added support for new kits
2.2.0	Added support for the OPTIGA Trust M Express and MTR chips

All referenced product or service names and trademarks are the property of their respective owners.

The Bluetooth® word mark and logos are registered trademarks owned by Bluetooth SIG, Inc., and any use of such marks by Infineon is under license.

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