NRF52 - Zephyr 2.4.4 - MCUboot image encryption

[Canadian_EE]

inter_less8_exer1_dualDFU_customkey_encryption.zip

I have attached a sample project. I end up with these sorts of errors, I am unclear how to resolve. 

[Canadian_EE]

Error: /src/boot_serial.c:634: undefined reference to `...\boot_handle_enc_fw' collect2.exe: error: ld returned 1 exit status ninja: build stopped:

...

FATAL ERROR: command exited with status 1: '...\bin\cmake.EXE' --build '...\inter_less8_exer1_dualDFU_customkey_encryption\build'