Research And Design Of Firmware Upgrade System For Internet Of Things Devices Based On BLE

Online firmware upgrade is one of the main methods of software iterative update in Internet of Things devices.Hundreds of devices can be easily upgraded by wirelessly transmitting firmware.Although the way of upgrading in the air is convenient,there are many security risks in the process of upgrading.In addition,the upgrade for a long time may affect the normal use of devices.The application programming upgrade has certain requirements on the memory of embedded devices.To solve the above problems,this paper designs a safe,efficient and universal remote firmware upgrade scheme.The main tasks are as follows:(1)Analyze the potential physical attack and wireless attack in the firmware upgrade process,and deeply explore the threat model of firmware upgrade.Aiming at these risks,a firmware upgrade security model suitable for Internet of Things devices is proposed to improve the firmware information security of devices from the aspects of firmware data packaging,wireless transmission,identity verification and terminal device storage protection.(2)Designed the firmware upgrade system of Internet of Things devices based on BLE.Two OTA server implementations,System on Chip(So C)mode and Network Co-processor(NCP)mode,are proposed to upgrade the firmware of remote OTA clients.The realization mechanism of serial port transmission in NCP mode is designed,and the firmware upgrade scheme is designed for the lower computer through serial port transmission.(3)The realization principle of LZ4,Deflate and LZMA data compression algorithm is studied.By testing and comparing the performance parameters of these three compression algorithms in compression ratio,running time and memory occupancy,the optimal parameters of LZMA algorithm suitable for data compression processing of Io T devices are selected and applied to the system implementation.Based on the above research,a Bootloader with data decompression,security design functions and serial port data communication is implemented.(4)A test environment for firmware upgrade was established to test the function and performance of the firmware upgrade system based on BLE and verify that the system can effectively resist possible hacker attacks through security encryption,digital signature,and other methods.The firmware upgrade system was also tested with a 2M PHY data rate in conjunction with the new features of the Bluetooth 5.0 specification.