Why did you make the secure dfu example so complicated ? The sample works but why is it so difficult??
@Hhuseyin: Have you tried to follow my guide here. I agree that getting started with the Secure DFU maybe a little bit complex but once you get used to the mechanism, it should be smooth.
We are actually working on Non-secure DFU so that if you want a smaller and more simple bootloader you can use it. But I don't know when it's available.
I follow the guide from Hung Bui which helps me: devzone.nordicsemi.com/.../