Combinatorial designs are powerful structures for key management in wireless sensor networks to address good connectivity and also security against external attacks in large scale networks. Many researchers have used key pre-distribution schemes using combinatorial structures in which key-rings, are pre-distributed to each sensor node before deployment in a real environment. Regarding the restricted resources, key distribution is a great engagement and challenging issue in providing sufficient security in wireless sensor networks. To provide secure communication, a unique key should be found from their stored key-rings. Most of the key pre-distribution protocols based on public-key mechanisms could not support highly scalable networks due to their key storage overhead and communication cost that linearly increasing. In this paper, we introduce a new key distribution approach for hierarchical clustered wireless sensor networks. Each cluster has a construction that contains new points or that reinforces and builds upon similar ideas of their head clusters. Based on Residual Design as a powerful algebraic combinatorial architecture and hierarchical network model, our approach guarantees good connectivity between sensor nodes and also cluster heads. Compared with similar existing schemes, our approach can provide sufficient security no matter if the cluster head or normal sensor node is compromised Manuscript profile

Near Field Communication (NFC), as a short-range wireless connectivity technology, makes it easier for electronic devices to stay in touch. This technology, due to its advantages such as secure access, compatibility, and ease of use, can be utilized in multiple applications in various domains such as banking, file transferring reservations, booking tickets, redeeming, entry/exit passes, and payment. In this survey paper, various aspects of this technology, including operating modes, their protocol stacks, and standard message format are investigated. Moreover, future direction of NFC in terms of design, improvement, and user-friendliness is presented for further research. In addition, due to the disadvantages of banknote-based payment methods such as the high temptation to steal and the need for a safe, mobile payments, which include mobile wallets and mobile money transfers, are explored as a new alternative to these methods. In addition, the traditional payment methods and their limitations are surveyed along with NFC payment as a prominent application of this technology. Furthermore, security threats of NFC payment along with future research directions for NFC payment and its challenges, including protocols and standards, and NFC payment security requirements are addressed in this paper. It is hoped that effective policies for NFC payment development will be provided by addressing the important challenges and formulating appropriate standards. Manuscript profile