Tham khảo tài liệu 'development and implementation of rfid technology part 6', kỹ thuật - công nghệ, cơ khí - chế tạo máy phục vụ nhu cầu học tập, nghiên cứu và làm việc hiệu quả | Development of Sensing and Computing Enhanced Passive RFID Tags Using the Wireless Identification and Sensing Platform 141 The ghost then transmits the badges response to the reader and the door is unlocked. In this scenario the ghost may be at the building door while the leech is in a coffee shop down the street where the employee is having lunch. The enabler of this attack is that the context of the badge is not factored into the access system protocol. This is largely because standard RFID offers no input vector to detect the context of the device. The sensing capabilities of the WISP can provide this context awareness and in the case of ghost and leech attacks it can be used to detect user intent. In Czeski et al. 2008 the 3D accelerometer of the WISP was used to implement a secret hand shake based authentication system to protect against ghost and leech attacks. When the user wants to authenticate a transaction or gain building access they first perform a gesture with the card which unlocks the card and enables communication. The gesture could be a figure eight or any unique movement that the card would not experience in everyday activity. Only if this handshake is correct will the WISP unlock and transmits its ID to the reader. This approach leverages not only the computational power of the WISP but also its sensing capabilities to provide a level of security that is not possible using standard IC tags. Passive data logger Several authors have demonstrated novel applications of passive RFID technology which benefit from wireless battery-free operation. However these systems are inherently limited by the requirement of tag proximity to a reader for power and finite wireless range due to RF path loss over distance. One particularly interesting class of applications involves a tagged item that travels between two reader-equipped locations but does not have reader proximity during transit. For example this situation occurs during cold chain transport for food
