https://devzone.nordicsemi.com/f/nordic-q-a/66841/dfu-dat-file-checksum-verificationHello, We are using nRF52840 with SDK 15.2.0, a bootloader and the SoftDevice. We are able to perform a DFU by downloading the .bin and .dat files of the new firmware in Flash memory, to fill the DFU settings structure with the correct values, and afteren-USTelligent Community 13Fri, 09 Oct 2020 09:23:43 GMThttps://devzone.nordicsemi.com/thread/273970?ContentTypeID=1Fri, 09 Oct 2020 09:23:43 GMT137ad170-7792-4731-bb38-c0d22fbe4515:65129943-6c49-4de4-a397-b83645f95d89Pierre cgwi22<p>Hi Amanda, thanks for your answer.</p> <p>Finally we have found the solution. With the help of the command &quot;<code>nrfutil pkg display my_file.zip&quot;</code> we have been able to discover where the SHA-256 hash of the .bin data is located in the .dat data. So now we can compute the hash of the .bin file and compare it to the expected hash in the .dat file.</p> <p>Our problem is solved.</p><div style="clear:both;"></div>https://devzone.nordicsemi.com/thread/273716?ContentTypeID=1Thu, 08 Oct 2020 11:49:03 GMT137ad170-7792-4731-bb38-c0d22fbe4515:4723a690-021e-48e0-ae70-b101ca047488Amanda Hsieh<p>Hi Pierre,&nbsp;</p> <p><span>Bootloader needs to know the checksum value of the application image in order to validate it on boot, and will fall back to DFU mode if it is unable to verify it.&nbsp; The checksum value along with other flags are stored in the bootloader settings page. You can take a look at&nbsp;<a title="BLE Secure DFU Bootloader" href="https://infocenter.nordicsemi.com/topic/sdk_nrf5_v17.0.2/ble_sdk_app_dfu_bootloader.html?cp=7_1_4_4_0">BLE Secure DFU Bootloader</a>&nbsp;on how to check CRC.&nbsp;</span></p> <p><span>-Amanda H.</span></p><div style="clear:both;"></div>