In the past few years, smart healthcare has become a popular topic. Many users wear smart devices to monitor their health conditions. To provide information for health analysis, many sensors are installed in smart wearable devices to collect personal health data. Due to the limitation of space and computational power, private health data is not processed locally. Instead, it is usually sent to a mobile phone for further analysis, which required wireless data exchange between the mobile phone and smart wearable devices. To protect a user’s privacy, it is important to guarantee the connection security of the devices’ network as well as prevent information leakage. A possible method to secure the data exchange process is symmetric encryption. In this paper, we investigate the feasibility of symmetric key generation for communication between a mobile phone and smart wearable device using angular velocity data collected by gyroscopes as data source. We collected over 1000 samples of gait data, totally more than 20000 seconds of movements, using two industrial products including a smart watch and mobile phone placed on wrist and in pocket respectively. We successfully generated the same random number for mobile phone and smart wearable device in 78% samples.

Abstract In computed tomography, the simulation of x‐ray projection is very important for developing and evaluating image reconstruction methods. Currently, the computer aided design models have been used for projection simulation. Compared with the stereolithographic model, the Unigraphics NX (UG) model can describe complex objects with multiple materials. However, calculating the intersection of a ray with a UG model can only be performed by an internal function, which greatly decreases the efficiency of the projection simulation. Therefore, we propose a fast method for projection simulation based on multi‐core. In this method, we use the internal function to calculate the intersection points and the corresponding face normal vectors for a ray. By computing the dot product between the direction vector of the ray and the face normal vectors, we can determine the entry and exit point pairs, and further obtain the simulation projection. On this basis, the projection simulation tasks are evenly decomposed to multiple processes. Then, we invoke these processes by multi‐thread in a main process, and realize parallel implementation of the projection simulation. Numerical experiments demonstrate the accuracy and effectiveness of the method, and we can obtain nearly linear speedup of the multi‐core acceleration.

Recently there has been a growing interest in short-range communication using audio channels for device pairing and as a self-jamming communication medium. Given that such channels are audible to participants they are considered more resistant to active attacks, i.e., the attack signal would be heard by the participants. In this paper, we investigate the validity of this assumption using two prominent acoustic self-jamming systems implementations. We show that basic overshadowing attacks are possible in these systems and that these attacks cannot be effectively detected by the participants if the attacker is close to the receiving device. Finally, we propose a novel physical-layer solution for effectively detecting overshadowing attacks, which can improve state-of-the-art acoustic self-jamming systems by ensuring channel integrity while not requiring fundamental modifications to these schemes.

Relay attacks is a serious and practical threat to contactless systems that is becoming more attractive with the increased use and transaction value of contactless payments. Distance-bounding is a countermeasure widely studied in academic research but it has not transferred to commercial systems. Conventional communication channels cannot achieve the theoretical properties often required for the protocol to be secure and special channels might not be feasible to adopt. Our objective is to design `best-effort' distance-bounding channels suitable for real RFID systems. In this paper we discuss standard channel implementation using off-the-shelf emulators and readers, and discuss potential modifications to channels implementable on current devices that would results in more relay-resistant channel designs. We are present reference relay attacks for ISO 14443A and Felica type systems using our implemented devices.