A client example failed when proper entropy collector has not been implemented

[toyowata]

In K64F platform, the macro MBEDTLS_ENTROPY_HARDWARE_ALT is defined in the target.json and proper implementation has been done in the HAL.

ARMmbed/mbed-os#1879

Some platforms do not support RNG hardware and expect to use software solution. e.g. build client example without MBEDTLS_ENTROPY_HARDWARE_ALT macro.

In that case, I got connection error below if I removed the MBEDTLS_ENTROPY_HARDWARE_ALT macro in K64F platform (as non RNG support device).

Starting mbed Client example...
Using Ethernet

Connected to Network successfully
IP address 10.128.4.32

SOCKET_MODE : UDP
Connecting to coap://api.connector.mbed.com:5684

[ERROR:] M2MInterface::SecureConnectionFailed

Attached files is mbed-trace log: trace_log_failed.txt

So, my question is:

• Is the MBEDTLS_ENTROPY_HARDWARE_ALT macro and entropy collector implementation mandatory feature, or optional?

If this is optional, the nanostack-hal-mbed-cmsis-rtos should also have software implementation and the client example should not fail.

https://github.com/ARMmbed/nanostack-hal-mbed-cmsis-rtos/blob/master/arm_hal_random.c#L28

[yogpan01]

@toyowata Please raise this issue for mbedTLS component, if underlying mbedTLS doesnt support other platform or then dont provide alternate software implementation, there is not much mbed CLient or for that matter any other component using mbedTLS can do about it

[toyowata]

@yogpan01 Thanks. I created the issue here.

[ciarmcom]

ARM Internal Ref: IOTCLT-878

[yogpan01]

Closing this issue as it is now solved by providing the work around for different hardware boards.