This video demonstrates a newly developed over-the-air (OTA) flasher for the "Call Me Smart Ring," which eliminates the need for previous interception methods. The flasher leverages Web Bluetooth, enabling direct firmware updates from modern browsers on both smartphones and PCs. The process is showcased, involving connection, firmware selection, and flashing, with a change in the device's Bluetooth name serving as confirmation of a successful update. The video also details the firmware's structure, highlighting the inclusion of a data length and CRC (Cyclic Redundancy Check) value within its header, and demonstrates how to verify this checksum. A significant finding is the absence of any signing or encryption on the firmware, indicating a remarkably open and easy update mechanism for the device.
Summarizing the Call Me Smart Ring OTA Flasher
0:02 Over-the-Air Flasher: The video introduces a new over-the-air (OTA) flasher for the "Call Me Smart Ring," simplifying the update process previously requiring application interception.
0:06 Web Bluetooth Compatibility: The flasher uses Web Bluetooth, making it accessible and compatible with most newer browsers on both smartphones and PCs.
0:39 Flashing Demonstration: The creator demonstrates the flashing process by connecting to the ring (initially named "r02"), selecting a new firmware file, and initiating the write operation.
1:19 Firmware Update Confirmation: After the firmware is written, the ring disconnects, its LED briefly blinks, and it reappears with a new Bluetooth name (e.g., "ATC 1086"), confirming the successful update.
1:48 Firmware Header Structure: The firmware includes a header with crucial information, such as the length of the raw firmware data (repeated twice) and a CRC value for integrity checking.
2:16 CRC Verification: The video illustrates how to calculate and verify the CRC value of the firmware using a hex editor (HxD), noting that the CRC needs to be entered in reverse.
2:40 Open Update Mechanism: A key takeaway is that the smart ring's firmware is not signed or encrypted, suggesting a straightforward and open mechanism for custom or modified firmware updates.