I installed SDK 15.3.0 build 59ac345 and started working though the DFU secure boot loader example. In the 15.3.0 documentation it says
Setup
You can find the source code and the project file of the example in the following folder: <InstallFolder>\examples\dfu\bootloader_secure_ble
But that boot loader_secure_ble directory isn't present. Did I miss a step here on installing the SDK?
RICHMAES-MBP:dfu richmaes$ pwd /opt/nRF5x/nRF5_SDK_15.3.0_59ac345/examples/dfu RICHMAES-MBP:dfu richmaes$ ls -alrt total 4 drwxr-xr-x 8 richmaes staff 256 Feb 14 13:06 open_bootloader drwxr-xr-x 4 richmaes staff 128 Feb 14 13:15 secure_dfu_test_images drwxr-xr-x 22 richmaes staff 704 Feb 14 13:19 secure_bootloader drwxr-xr-x 18 richmaes staff 576 Mar 15 08:41 .. drwxr-xr-x 6 richmaes staff 192 Mar 15 08:42 . -rw-r--r-- 1 richmaes staff 631 Mar 15 08:42 dfu_public_key.c RICHMAES-MBP:dfu richmaes$