900 research outputs found
Efficient and Low-Cost RFID Authentication Schemes
Security in passive resource-constrained Radio Frequency Identification
(RFID) tags is of much interest nowadays. Resistance against illegal tracking,
cloning, timing, and replay attacks are necessary for a secure RFID
authentication scheme. Reader authentication is also necessary to thwart any
illegal attempt to read the tags. With an objective to design a secure and
low-cost RFID authentication protocol, Gene Tsudik proposed a timestamp-based
protocol using symmetric keys, named YA-TRAP*. Although YA-TRAP* achieves its
target security properties, it is susceptible to timing attacks, where the
timestamp to be sent by the reader to the tag can be freely selected by an
adversary. Moreover, in YA-TRAP*, reader authentication is not provided, and a
tag can become inoperative after exceeding its pre-stored threshold timestamp
value. In this paper, we propose two mutual RFID authentication protocols that
aim to improve YA-TRAP* by preventing timing attack, and by providing reader
authentication. Also, a tag is allowed to refresh its pre-stored threshold
value in our protocols, so that it does not become inoperative after exceeding
the threshold. Our protocols also achieve other security properties like
forward security, resistance against cloning, replay, and tracking attacks.
Moreover, the computation and communication costs are kept as low as possible
for the tags. It is important to keep the communication cost as low as possible
when many tags are authenticated in batch-mode. By introducing aggregate
function for the reader-to-server communication, the communication cost is
reduced. We also discuss different possible applications of our protocols. Our
protocols thus capture more security properties and more efficiency than
YA-TRAP*. Finally, we show that our protocols can be implemented using the
current standard low-cost RFID infrastructures.Comment: 21 pages, Journal of Wireless Mobile Networks, Ubiquitous Computing,
and Dependable Applications (JoWUA), Vol 2, No 3, pp. 4-25, 201
A Commentary on the Work of Saks and Wigderson 1986: Correlated Distributions on an Unbalanced Binary AND-OR Tree (Proof theory and related topics)
We discuss the game-theoretical equilibrium of an AND-OR tree. Here, correlated distributions on the truth assignments are taken into consideration. In the seminal paper of Saks and Wigderson (1986), they proposed a recurrence formula method to calculate the equilibrium value. They provided a proof only for the case of complete binary trees. As to unbalanced binary trees, without a proof, they wrote that the main result for the complete binary trees holds for nearly balanced trees. However, their definition of a nearly balanced tree is vague. This note is a commentary on the paper of Saks and Wigderson with a particular focus on unbalanced binary trees. We propose the concept of a weakly balanced tree as an alternative to the concept of a nearly balanced tree. We demonstrate that the recurrence formula method of Saks and Wigderson works well for weakly balanced trees
High pressure growth and electron transport properties of superconducting SmFeAsO1-xHx single crystals
We report the single crystal growth and characterization of the highest Tc
iron-based superconductor SmFeAsO1-xHx. Some sub-millimeter-sized crystals were
grown using the mixture flux of Na3As + 3NaH + As at 3.0 GPa and 1473 K. The
chemical composition analyses confirmed 10% substitution of hydrogen for the
oxygen site (x = 0.10), however, the structural analyses suggested that the
obtained crystal forms a multi-domain structure. By using the FIB technique we
fabricated the single domain SmFeAsO0.9H0.10 crystal with the Tc of 42 K, and
revealed the metallic conduction in in-plane (rhoab), while semiconducting in
the out-of-plane (rhoc). From the in-plane Hall coefficient measurements, we
confirmed that the dominant carrier of SmFeAsO0.9H0.10 crystal is an electron,
and the hydride ion occupied at the site of the oxygen ion effectively supplies
a carrier electron per iron following the equation: O2- = H- + e-.Comment: 4 figures, 2 table
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