https://devzone.nordicsemi.com/f/nordic-q-a/25779/what-is-the-difference-b-w-legacy-dfu-and-secure-dfuhi, i am working on NRF52 with SDK v11, softdevice S132. i have implemented my application with DFU as per the HRM example in SDK v11. now i want to know about what is secure dfu and is it possible to edit my legacy DFU to make it as Secure DFU. anden-USTelligent Community 13Mon, 09 Oct 2017 12:04:58 GMThttps://devzone.nordicsemi.com/thread/101547?ContentTypeID=1Mon, 09 Oct 2017 12:04:58 GMT137ad170-7792-4731-bb38-c0d22fbe4515:8f17cf76-87d0-4804-9612-fb8a08930195J&#248;rgen Holmefjord<p>Hi,</p> <p>Secure DFU is more secure in the way that only signed and verified firmware images can be updated. You sign the firmwares using a private key, and the bootloader will verify the image using a matching public key. If the bootloader cannot verify the image, it will not update it. With the legacy bootloader, all valid firmware images would be accepted and updated, exposing the device for unauthorized firmware updates. You can read more about the <a href="http://infocenter.nordicsemi.com/topic/com.nordic.infocenter.sdk5.v12.0.0/lib_bootloader_modules.html?cp=4_0_5_3_4">details of the secure bootloader</a> in the infocenter.</p> <p>It is possible to update to the secure bootloader, but this will require that you have reserved more space on in flash that the size of the legacy bootloader. See <a href="https://devzone.nordicsemi.com/question/94387/is-bootloader-in-sdk12-compatible-with-the-bootloader-before-sdk12/?answer=94478#post-id-94478">this answer</a> for more details.</p> <p>Best regards,</p> <p>Jørgen</p><div style="clear:both;"></div>