Secure TCP client

This code example demonstrates the implementation of a secure TCP client with PSOC™ 6 MCU with AIROC™ CYW43xxx Wi-Fi & Bluetooth® combo chips.

In this example, the TCP client establishes a secure connection with a TCP server through an SSL handshake. After the SSL handshake completes successfully, the TCP client turns the user LED ON or OFF based on the command received from the TCP server. The Wi-Fi device can be brought up in either STA interface or Soft AP interface mode. Additionally, this code example can be configured to work with IPv4 or link-local IPv6 addressing mode.

This example uses the Wi-Fi Core FreeRTOS lwIP mbedtls library of the SDK. This library enables application development based on Wi-Fi, by pulling wifi-connection-manager, FreeRTOS, lwIP, Mbed TLS, Secure sockets, and other dependent modules. The Secure sockets library provides an easy-to-use API by abstracting the network stack (lwIP) and the security stack (Mbed TLS).

View this README on GitHub.

Provide feedback on this code example.

Requirements

• ModusToolbox™ v3.2 or later (tested with v3.3)
• Board support package (BSP) minimum required version: 4.0.0
• Programming language: C
• Associated parts: All PSOC™ 6 MCU parts, AIROC™ CYW20819 Bluetooth® & Bluetooth® LE SoC, AIROC™ CYW43012 Wi-Fi & Bluetooth® combo chip, AIROC™ CYW4343W Wi-Fi & Bluetooth® combo chip, AIROC™ CYW4373 Wi-Fi & Bluetooth® combo chip, AIROC™ CYW43439 Wi-Fi & Bluetooth® combo chip, AIROC™ CYW43022 Wi-Fi & Bluetooth® combo chip

Supported toolchains (make variable 'TOOLCHAIN')

• GNU Arm® Embedded Compiler v11.3.1 (GCC_ARM) – Default value of TOOLCHAIN
• Arm® Compiler v6.22 (ARM)
• IAR C/C++ Compiler v9.50.2 (IAR)

Supported kits (make variable 'TARGET')

• PSOC™ 62S2 Wi-Fi Bluetooth® Prototyping Kit (CY8CPROTO-062S2-43439) – Default value of TARGET
• PSOC™ 6 Wi-Fi Bluetooth® Prototyping Kit (CY8CPROTO-062-4343W)
• PSOC™ 6 Wi-Fi Bluetooth® Pioneer Kit (CY8CKIT-062-WIFI-BT)
• PSOC™ 62S2 Wi-Fi Bluetooth® Pioneer Kit (CY8CKIT-062S2-43012)
• PSOC™ 62S1 Wi-Fi Bluetooth® Pioneer Kit (CYW9P62S1-43438EVB-01)
• PSOC™ 62S1 Wi-Fi Bluetooth® Pioneer Kit (CYW9P62S1-43012EVB-01)
• PSOC™ 62S3 Wi-Fi Bluetooth® Prototyping Kit (CY8CPROTO-062S3-4343W)
• PSOC™ 64 "Secure Boot" Wi-Fi Bluetooth® Pioneer Kit (CY8CKIT-064B0S2-4343W)
• PSOC™ 62S2 Evaluation Kit (CY8CEVAL-062S2-LAI-4373M2, CY8CEVAL-062S2-LAI-43439M2, CY8CEVAL-062S2-MUR-43439M2, CY8CEVAL-062S2-MUR-4373EM2, CY8CEVAL-062S2-MUR-4373M2, CY8CEVAL-062S2-CYW43022CUB, CY8CEVAL-062S2-CYW955513SDM2WLIPA)
• XMC7200 Evaluation Kit (KIT_XMC72_EVK_MUR_43439M2)
• PSOC™ 6 AI Evaluation Kit (CY8CKIT-062S2-AI)

Hardware setup

This example uses the board's default configuration. See the kit user guide to ensure that the board is configured correctly.

Note: The PSOC™ 6 Bluetooth® LE Pioneer Kit (CY8CKIT-062-BLE) and the PSOC™ 6 Wi-Fi Bluetooth® Pioneer Kit (CY8CKIT-062-WIFI-BT) ship with KitProg2 installed. ModusToolbox™ requires KitProg3. Before using this code example, make sure that the board is upgraded to KitProg3. The tool and instructions are available in the Firmware Loader GitHub repository. If you do not upgrade, you will see an error like "unable to find CMSIS-DAP device" or "KitProg firmware is out of date".

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.

Install the Python interpreter if you do not have one. This code example is tested using Python 3.7.7.

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 "Secure TCP client" application with the desired name "SecureTcpClient" configured for the CY8CPROTO-062S2-43439 BSP into the specified working directory, C:/mtb_projects:

project-creator-cli --board-id CY8CPROTO-062S2-43439 --app-id mtb-example-wifi-secure-tcp-client --user-app-name SecureTcpClient --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

If using a PSOC™ 64 "Secure" MCU kit (like CY8CKIT-064B0S2-4343W), the PSOC™ 64 device must be provisioned with keys and policies before being programmed. Follow the instructions in the "Secure Boot" SDK user guide to provision the device. If the kit is already provisioned, copy-paste the keys and policy folder to the application folder.

Note: Use policy_single_CM0_CM4_smif_swap.json policy instead of using the default one "policy_single_CM0_CM4_swap.json" to provision CY8CKIT-064B0S2-4343W device.

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

2. The kit can be configured to run either in the Wi-Fi STA interface mode or in AP interface mode. The interface mode is configured using the USE_AP_INTERFACE macro defined in the network_credentials.h file. Based on the desired interface mode, do the following:

   Kit in STA mode (default interface):

   1. Set the USE_AP_INTERFACE macro to 0. This is the default mode.

   2. Modify the WIFI_SSID, WIFI_PASSWORD, and WIFI_SECURITY_TYPE macros to match with the Wi-Fi network credentials that you want to connect. These macros are defined in the network_credentials.h file. Ensure that the Wi-Fi network that you are connecting to is configured as a private network for the proper functioning of this example.

   Kit in AP mode:

   1. Set the USE_AP_INTERFACE macro to 1.

   2. Update SOFTAP_SSID, SOFTAP_PASSWORD, and SOFTAP_SECURITY_TYPE macros as desired. This step is optional.

3. Configure the IP addressing mode. By default, IPv4-based addressing is used. To use IPv6 addressing mode, set the USE_IPV6_ADDRESS macro defined in the secure_tcp_server.h file as follows:

   #define USE_IPV6_ADDRESS				      (1)
   

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

5. 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
   

   After programming, the application starts automatically. Confirm that the text as shown in either one of the following figures is displayed on the UART terminal. Note that the Wi-Fi SSID and the IP address assigned will be different based on the network that you have connected to; in AP mode, the AP credentials will be different based on your configuration in Step 2.

   Figure 1. Wi-Fi connection status (IPv4 address and STA mode)

   

   
   

   Figure 2. Wi-Fi connection status (IPv6 address and STA mode)

   

   
   

   Figure 3. Wi-Fi connection status (IPv4 address and AP mode)

   

   Similarly, when the code example is configured for IPv6 and AP mode, the IPv4 address displayed in Figure 3 will be replaced by the IPv6 address.

6. Connect your PC to the Wi-Fi AP that you have configured in Step 2:

   • In STA mode: Connect the PC to the same AP to which the kit is connected.

   • In AP mode: Connect the PC to the kit's AP.

7. Determine the PC's IP address.

   To determine the IP address, type the following command in the command shell based on your operating system:

   Windows: ipconfig

   Linux: curl ifconfig.me

   macOS: ifconfig |grep inet

8. Ensure that the Python interpreter (see Software setup) is installed on your PC.

9. Open a command shell from the project directory and run the Python TCP secure server ({project directory}\python-secure-tcp-server).

10. In the command shell opened in the project directory, type the following command based on the IP addressing mode configuration:

    For IPv4-based addressing:

    python tcp_secure_server.py
    

    For link-local IPv6-based addressing:

    python tcp_secure_server.py ipv6
    

    Note: Ensure that the firewall settings of your PC allow access to the Python software so that it can communicate with the TCP client. For more details on enabling Python access, see this community thread.

11. In the terminal program, enter the IP address determined in Step 7.

12. From the Python secure TCP server, send the command to turn the LED ON or OFF to the TCP client ('0' to turn the LED OFF and '1' to turn the LED ON). Observe the user LED (CYBSP_USER_LED) turning ON/OFF on the board.

Figure 4. LED status on TCP server (IPv4 addressing mode)

Figure 5. LED status on TCP client (IPv4 addressing and STA mode)

Figure 6. LED status on TCP client (IPv4 addressing and AP mode)

Figure 7. LED status on TCP server (IPv6 addressing mode)

Figure 8. LED status on TCP client (IPv6 addressing and STA mode)

When the code example is configured in AP and IPv6 mode, the only change from Figure 4 is the IPv6 address being displayed instead of IPv4.

Note: Instead of using the Python TCP server (tcp_secure_server.py), you can use the mtb-example-wifi-secure-tcp-server example to run as the TCP server on the second kit. See the code example documentation to learn how to use the example.

If you are using the example as the server, the IP address (TCP_SERVER_IP_ADDRESS) configured in Step 6 in the Operation section should be that of the IP address assigned to the kit in the example.

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

Resources and settings

This example uses the Arm® Cortex®-M4 (CM4) CPU of PSOC™ 6 MCU to execute an RTOS task: TCP client task. At device reset, the default Cortex®-M0+ (CM0+) application enables the CM4 CPU and configures the CM0+ CPU to go to sleep.

In this example, the TCP client establishes a secure connection with the TCP server through an SSL handshake. During the SSL handshake, the client presents its SSL certificate (self-signed) for verification and also verifies the server's identity to which it is connecting.

Once the SSL handshake completes successfully, the TCP client controls the user LED to turn ON or OFF based on the command received from the TCP server.

Table 1. Application resources

Resource	Alias/object	Purpose
SDIO (HAL)	sdio_obj	SDIO interface for Wi-Fi connectivity
UART (HAL)	cy_retarget_io_uart_obj	UART HAL object used by retarget-io for debug UART port
LED (BSP)	CYBSP_USER_LED	User LED to show output

Creating a self-signed SSL certificate

The TCP client demonstrated in this example uses a self-signed SSL certificate. This requires OpenSSL which is already preloaded in ModusToolbox™. Self-signed SSL certificate means that there is no third-party certificate issuing authority, commonly referred to as CA, involved in the authentication of the client.

Note: Servers connecting to this client must have an exact copy of the SSL certificate to verify the client's identity.

Generate SSL certificate and private key

Follow these steps to generate a self-signed SSL certificate:

1. Run the following command with a CLI (on Windows, use the command line modus-shell program provided in ModusToolbox™ instead of a standard Windows command-line application) to generate the CA certificate using the following commands. Follow the instructions in the command window to provide the details required.

   openssl ecparam -name prime256v1 -genkey -noout -out root_ca.key
   openssl req -new -x509 -sha256 -key root_ca.key -out root_ca.crt -days 1000
   

2. Generate the client key pair and client certificate (signed using the CA certificate from Step 1). Follow the instructions in the command window to provide the details required.

   openssl ecparam -name prime256v1 -genkey -noout -out client.key
   openssl req -new -sha256 -key client.key -out client.csr
   openssl x509 -req -in client.csr -CA root_ca.crt -CAkey root_ca.key -CAcreateserial -out client.crt -days 1000 -sha256
   

3. Follow the instructions in the command window to provide the details required for creating the SSL certificate and private key.

   Note: The client.crt file is your client's certificate and client.key is your client's private key.

Related resources

Resources	Links
Application notes	AN228571 – Getting started with PSOC™ 6 MCU on ModusToolbox™ 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
Development kits	Select your kits from the Evaluation board finder.
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	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.

Document history

Document title: CE229252 - Secure TCP client

Version	Description of change
1.0.0	New code example
1.1.0	Updated for ModusToolbox™ 2.1 Code updated to use secure sockets and Wi-Fi connection manager libraries
1.2.0	Makefile updated to sync with BSP changes Code updated to use binary semaphore
1.3.0	Updated to add link-local IPv6 support
2.0.0	Major update to support ModusToolbox™ v2.2, added support for new kits Added soft AP Wi-Fi interface mode This version is not backward compatible with ModusToolbox™ software v2.1. Updated to support FreeRTOS v10.3.1
2.1.0	Updated to FreeRTOS v10.4.3 Added support for new kits
3.0.0	Updated to support ModusToolbox™ v2.4 Added support for new kits Updated the BSPs to v3.X
4.0.0	Major update to support ModusToolbox™ v3.0 and BSPs v4.X. This version is not backward compatible with previous versions of ModusToolbox™
4.1.0	Added support for CY8CKIT-064B0S2-4343W
4.2.0	Added support for CY8CEVAL-062S2-LAI-43439M2
4.3.0	Added support for CY8CPROTO-062S2-43439
4.4.0	Added support for CY8CEVAL-062S2-MUR-4373EM2 and CY8CEVAL-062S2-MUR-4373M2
4.5.0	Added support for KIT_XMC72_EVK_MUR_43439M2 Updated to support mbedtls v3.4.0 and ModusToolbox™ v3.1.
4.6.0	Added support for CY8CEVAL-062S2-CYW43022CUB
4.7.0	Added support for CY8CKIT-062S2-AI
4.8.0	Added support for CY8CEVAL-062S2-CYW955513SDM2WLIPA
4.8.1	Disabled D-cache for XMC7000 based BSPs
4.9.0	Updated Python script to filter input data Enabled D-cache support for XMC7000 devices

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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