How to connect to AWS IoT Core using AWS Embedded SDK from coreMQTT library using mbedTLS

Hi misterb.

The fleet provisioning demo uses mbedTLS: https://github.com/aws/aws-iot-device-sdk-embedded-C/blob/main/demos/fleet_provisioning/fleet_provisioning_with_csr/mqtt_operations.c#L673lL692

Implementation of the transport layer here: https://github.com/aws/aws-iot-device-sdk-embedded-C/blob/main/platform/posix/transport/src/mbedtls_pkcs11_posix.c

You can find more examples in the FreeRTOS and amazon-freertos repos.

Please see here: https://www.freertos.org/network-interface.html

The transport interface implementations included in the FreeRTOS download are split into two files - a wrapper C file specific to the TCP stack, and a supplemental C file specific to using a TLS stack with the selected TCP stack. For example, to use FreeRTOS+TCP with mbedTLS, build sockets_wrapper.c from the network_transport/freertos_plus_tcp directory in the source code distribution, then build using_mbedtls.c from the using_mbedtls subdirectory.

Available transports: https://github.com/FreeRTOS/FreeRTOS/tree/main/FreeRTOS-Plus/Source/Application-Protocols/network_transport

mbedtls in particular: https://github.com/FreeRTOS/FreeRTOS/blob/main/FreeRTOS-Plus/Source/Application-Protocols/network_transport/using_mbedtls/using_mbedtls.c

And part of the demos that use it: https://github.com/FreeRTOS/FreeRTOS/blob/main/FreeRTOS-Plus/Demo/AWS/Mqtt_Demo_Helpers/mqtt_demo_helpers.c#L614-L624

The amazon-freertos repo contains embedded reference implementations for many boards. You can find a coreMQTT demo there: https://github.com/aws/amazon-freertos/blob/main/demos/coreMQTT/mqtt_demo_mutual_auth.c

An mbedtls transport implementation here: https://github.com/aws/amazon-freertos/blob/main/libraries/freertos_plus/standard/tls/src/iot_tls.c

The demo calls this through one of the secure sockets implementations:

• https://github.com/aws/amazon-freertos/blob/main/libraries/abstractions/secure_sockets/freertos_plus_tcp/iot_secure_sockets.c
• https://github.com/aws/amazon-freertos/blob/main/libraries/abstractions/secure_sockets/lwip/iot_secure_sockets.c