Storage-Awareness: RFID Private Authentication based on Sparse Tree

As the growing use of radio frequency identification (RFID) technology to enhance ubiquitous computing environments, the privacy protection problem becomes a crucial issue. The objective of private authentication for RFID systems is to allow valid readers explicitly authenticate their dominated tags without leaking tags´ private information. To achieve strong privacy, recently, Lu et al. propose a Strong and lightweight RFID Private Authentication protocol (SPA), which enables dynamic key-updating mechanism for balanced tree based authentication approaches. However, due to its balanced tree structure, SPA is still susceptible to compromising attacks. In this paper, we propose a Storage-Aware Private Authentication protocol (SAPA). This scheme employs the sparse tree structure, and treats the path of each tag in the tree as an independent secret. As a result, SAPA enjoys perfect privacy and largely reduces the space for storing key sequence on the side of the tag, while keeping the key search complexity on the side of the reader still be logarithmic.