HTTPS Client

The HTTPS Client sample demonstrates a minimal implementation of HTTP communication. It shows how to set up a TLS session towards an HTTPS server and how to send an HTTP request. The sample connects to an LTE network using an nRF91 Series DK or to Wi-Fi using the nRF7002 DK through the connection manager API.

Requirements 

The sample supports the following development kits:

Hardware platforms	PCA	Board name	Build target
nRF9161 DK		`nrf9161dk_nrf9161`	`nrf9161dk_nrf9161_ns`
nRF9160 DK	PCA10090	nrf9160dk_nrf9160	`nrf9160dk_nrf9160_ns`
nRF7002 DK	PCA10143	nrf7002dk_nrf5340	`nrf7002dk_nrf5340_cpuapp`

When built for an _ns build target, the sample is configured to compile and run as a non-secure application with Cortex-M Security Extensions enabled. Therefore, it automatically includes Trusted Firmware-M that prepares the required peripherals and secure services to be available for the application.

Overview 

The sample first initializes the Modem library and AT communications. Next, it provisions a root CA certificate to the modem using the Modem key management library. When using an nRF91 Series device, the provisioning must be done before connecting to the LTE network, because the certificates can only be provisioned when the device is not connected.

The sample then establishes a connection to the network, sets up the necessary TLS socket options, and connects to an HTTPS server. It sends an HTTP HEAD request and prints the response code in the terminal.

Obtaining a certificate 

The sample connects to www.example.com, which requires an X.509 certificate. This certificate is provided in the samples/net/https_client/cert folder.

To connect to other servers, you might need to provision a different certificate. See Certificates for more information.

Using Mbed TLS and TF-M 

This sample supports using Mbed TLS and Trusted Firmware-M (TF-M). Instead of offloading the TLS sockets into the modem, you can use the Mbed TLS library from Zephyr. Using the Zephyr Mbed TLS, you can still use the offloaded sockets. Mbed TLS offers more configuration options than using the offloaded TLS handling.

When using TF-M and Mbed TLS with PSA crypto, all the crypto operations are run on the secure side on the device.

Sending traces over UART on an nRF91 Series DK 

To send modem traces over UART on an nRF91 Series DK, configuration must be added for the UART device in the devicetree and Kconfig. This is done by adding the modem trace UART snippet when building and programming.

Use the Cellular Monitor app for capturing and analyzing modem traces.

Building and running 

This sample can be found under samples/net/https_client in the nRF Connect SDK folder structure.

When built as firmware image for the _ns build target, the sample has Cortex-M Security Extensions (CMSE) enabled and separates the firmware between Non-Secure Processing Environment (NSPE) and Secure Processing Environment (SPE). Because of this, it automatically includes the Trusted Firmware-M (TF-M). To read more about CMSE, see Processing environments.

To build the sample with Visual Studio Code, follow the steps listed on the How to build an application page in the nRF Connect for VS Code extension documentation. See Building and programming an application for other building and programming scenarios and Testing and debugging an application for general information about testing and debugging in the nRF Connect SDK.

To build the sample with Mbed TLS and TF-M, add the following to your west build command:

-DOVERLAY_CONFIG=overlay-tfm_mbedtls.conf

The default packet data network (PDN) configuration is dual stack, which will use an IPv6 address if available (and IPv4 if not).

For testing IPv4 only, you might need to configure the packet data network settings, adding the following to your build command:

-DOVERLAY_CONFIG=overlay-pdn_ipv4.conf

Testing 

After programming the sample to your development kit, test it by performing the following steps:

Connect the USB cable and power on or reset your DK.
Open a terminal emulator and observe that the sample starts, provisions certificates, connects to the network and to example.com, and then sends an HTTP HEAD request.
Observe that the HTTP HEAD request returns HTTP/1.1 200 OK.

Sample output 

Output for the default configuration (dual stack, IPV4V6) where the carrier does not support IPv6:

HTTPS client sample started
Certificate match
Waiting for network.. PDP context 0 activated
OK
Waiting for IPv6..
IPv6 not available
Looking up example.com
Resolved 93.184.216.34 (AF_INET)
Connecting to example.com:443
Sent 61 bytes
Received 370 bytes

>        HTTP/1.1 200 OK

Finished, closing socket.
PDP context 0 deactivated

Output for the default configuration, where the carrier does support IPv6:

HTTPS client sample started
Bringing network interface up
Provisioning certificate
Certificate match
Connecting to the network
Looking up example.com
Resolved 2606:2800:220:1:248:1893:25c8:1946 (AF_INET6)
Connecting to example.com:443
Sent 61 bytes
Received 370 bytes

>        HTTP/1.1 200 OK

Finished, closing socket.
PDP context 0 deactivated

Output where you override the default packet data network (PDN) configuration to IPv4 only, via the overlay-pdn_ipv4.conf overlay:

HTTPS client sample started
Bringing network interface up
Provisioning certificate
Looking up example.com
Resolved 93.184.216.34 (AF_INET)
Connecting to example.com:443
Sent 61 bytes
Received 370 bytes

>        HTTP/1.1 200 OK

Finished, closing socket.

Dependencies 

This sample uses the following nRF Connect SDK libraries:

It uses the following sdk-nrfxlib library:

Modem library

In addition, it uses the following secure firmware component:

Trusted Firmware-M

This sample also offers a possibility to use the TF-M module that is at modules/tee/tfm/ in the nRF Connect SDK folder structure.