Protecting against key-exposure: strongly key-insulated encryption with optimal threshold

Key-insulated encryption schemes use a combination of key splitting and key evolution to protect against key exposure. Existing schemes, however scale poorly, having cost proportional to the number t of time periods that may be compromised by the adversary, and thus are practical only for small values of t. Yet in practice t might be large. This paper presents a strongly key-insulated encryption scheme with optimal threshold. In our scheme, t need not be known in advance and can be as large as one less than the total number of periods, yet the cost of the scheme is not impacted. This brings key-insulated encryption closer to practice. Our scheme is based on the Boneh-Franklin identity-based encryption (IBE) scheme [9], and exploits algebraic properties of the latter. Another contribution of this paper is to show that (not strongly) key-insulated encryption with optimal threshold and allowing random-access key updates (which our scheme and all others known allow) is equivalent to a restricted form of IBE. This means that the connection between key-insulated encryption and IBE is not accidental. Supported in part by NSF grants CCR-0098123, ANR-0129617 and CCR-0208842, and by an IBM Faculty Partnership Development Award. Supported in part by an NSF graduate fellowship.     

Secure video communication using firefly optimization and visual cryptography

In recent years, we face an increasing interest in protecting multimedia data and copyrights due to the high exchange of information. Attackers are trying to get confidential information from various sources, which brings the importance of securing the data. Many researchers implemented techniques to hide secret information to maintain the integrity and privacy of data. In order to protect confidential data, histogram-based reversible data hiding with other cryptographic algorithms are widely used. Therefore, in the proposed work, a robust method for securing digital video is suggested. We implemented histogram bit shifting based reversible data hiding by embedding the encrypted watermark in featured video frames. Histogram bit shifting is used for hiding highly secured watermarks so that security for the watermark symbol is also being achieved. The novelty of the work is that only based on the quality threshold a few unique frames are selected, which holds the encrypted watermark symbol. The optimal value for this threshold is obtained using the Firefly Algorithm. The proposed method is capable of hiding high-capacity data in the video signal. The experimental result shows the higher capacity and video quality compared to other reversible data hiding techniques. The recovered watermark provides better identity identification against various attacks. A high value of PSNR and a low value of BER and MSE is reported from the results.

     

Spin valve effect in sputtered FL-MoS2 and ferromagnetic shape memory alloy based magnetic tunnel junction

In the last decade, two-dimensional (2D) transition metal dichalcogenides have been introduced with great significance in the spintronic devices for their extraordinary electrical, optical, and spin-dependent properties. In this work, we have fabricated a few-layer molybdenum disulfide (FL-MoS₂) (~6 nm) as a non-magnetic spacer layer in Ni–Mn–In/FL-MoS₂/Ni–Mn–In magnetic tunnel junction (MTJ) using DC magnetron sputtering. FL-MoS₂ thin film sandwiched between two ferromagnetic shape memory alloy based electrodes exhibit semiconducting behavior, confirmed by current-voltage (I–V) characteristics and temperature dependent resistance measurement. The fabricated MTJ shows spin valve effect in the presence of an external magnetic field. The tunneling magnetoresistance (TMR) has been recorded in 10 K–300 K temperature range. The highest TMR ratio of 0.51% was obtained at a low temperature ~10 K, corresponding to the spin polarization of ~5%. This TMR ratio reduces to a value of 0.032% as the temperature of the device increases up to 300 K, displaying a finite TMR at room temperature. A detailed study of thickness and temperature-dependent magnetization versus magnetic field (M ? H) hysteresis loops of Ni–Mn–In thin films has been performed to understand the complex TMR behavior. The present study paves the way for the use of sputtered FL-MoS₂ and ferromagnetic shape memory alloy in ultrafast spintronics for advanced magnetic devices application.     

Statistical analysis of manual segmentations of structures in medical images

The problem of extracting anatomical structures from medical images is both very important and difficult. In this paper we are motivated by a new paradigm in medical image segmentation, termed Citizen Science, which involves a volunteer effort from multiple, possibly non-expert, human participants. These contributors observe 2D images and generate their estimates of anatomical boundaries in the form of planar closed curves. The challenge, of course, is to combine these different estimates in a coherent fashion and to develop an overall estimate of the underlying structure. Treating these curves as random samples, we use statistical shape theory to generate joint inferences and analyze this data generated by the citizen scientists. The specific goals in this analysis are: (1) to find a robust estimate of the representative curve that provides an overall segmentation, (2) to quantify the level of agreement between segmentations, both globally (full contours) and locally (parts of contours), and (3) to automatically detect outliers and help reduce their influence in the estimation. We demonstrate these ideas using a number of artificial examples and real applications in medical imaging, and summarize their potential use in future scenarios.     

Hardystonite improves biocompatibility and strength of electrospun polycaprolactone nanofibers over hydroxyapatite: A comparative study

The aim of this study was to compare physico-chemical and biological properties of hydroxyapatite (HA) and hardystonite (HS) based composite scaffolds. Hardystonite (Ca₂ZnSi₂O₇) powders were synthesized by a sol–gel method while polycaprolactone–hardystonite (PCL–HS) and polycaprolactone–hydroxyapatite (PCL–HA) were fabricated in nanofibrous form by electrospinning. The physico-chemical and biological properties such as tensile strength, cell proliferation, cell infiltration and alkaline phosphatase activity were determined on both kinds of scaffolds. We found that PCL–HS scaffolds had better mechanical strength compared to PCL–HA scaffolds. Addition of HA and HS particles to PCL did not show any inhibitory effect on blood biocompatibility of scaffolds when assessed by hemolysis assay. The in vitro cellular behavior was evaluated by growing murine adipose-tissue-derived stem cells (mE-ASCs) over the scaffolds. Enhanced cell proliferation and improved cellular infiltrations on PCL–HS scaffolds were observed when compared to HA containing scaffolds. PCL–HS scaffolds exhibited a significant increase in alkaline phosphatase (ALP) activity and better mineralization of the matrix in comparison to PCL–HA scaffolds. These results clearly demonstrate the stimulatory role of Zn and Si present in HS based composite scaffolds, suggesting their potential application for bone tissue engineering.     

Optimization of processing parameters of medium density fiberboard using response surface methodology for multiwalled carbon nanotubes as a nanofiller

In the present work, medium density fiberboard (MDF) panels were produced using multiwalled carbon nanotubes (MWCNT) reinforced urea formaldehyde resin. Response surface methodology was employed to optimize the relationship between the three variables, viz. pressing time, percentage of UF resin and percentage of MWCNT, used in the fabrication of MDF, and the influence of variables on the internal bonding (IB) and modulus of rupture (MOR) was studied. The optimum conditions based on the IB strength were determined as 8.18 % of UF resin, pressing time of 232 s, and MWCNT of 3.5 %. Similarly, the optimized conditions for MOR are also reported in this paper.     

Performance of insulated FRP-strengthened concrete flexural members under fire conditions

This paper presents the results of fire resistance tests on carbon fiber-reinforced polymer (CFRP) strengthened concrete flexural members, i.e., T-beams and slabs. The strengthened members were protected with fire insulation and tested under the combined effects of thermal and structural loading. The variables considered in the tests include the applied load level, extent of strengthening, and thickness of the fire insulation applied to the beams and slabs. Furthermore, a previously developed numerical model was validated against the data generated from the fire tests; subsequently, it was utilized to undertake a case study. Results from fire tests and numerical studies indicate that owing to the protection provided by the fire insulation, the insulated CFRP-strengthened beams and slabs can withstand four and three hours of standard fire exposure, respectively, under service load conditions. The insulation layer impedes the temperature rise in the member; therefore, the CFRP–concrete composite action remains active for a longer duration and the steel reinforcement temperature remains below 400°C, which in turn enhances the capacity of the beams and slabs.     

Simulation of population balance model-based particulate processes via parallel and distributed computing

Population Balance Models (PBMs), a class of integro partial differential equations, are utilized for simulating dynamics of numerous particulate systems. PBMs describe the time evolutions and distributions of many particulate processes and their efficient and quick simulation are critical for enhanced process control and optimization, especially for real-time applications. However, their intensive computational resource requirement is largely a prohibitive factor in the utility of PBMs for control and optimization. This paper describes how distributed computing systems may be leveraged to execute PBM-based simulations thus achieving time savings, using MATLAB's Distributed Computing Toolbox. A parallel computing algorithm was developed for a three dimensional and four dimensional population balance model with built-in constructs such as SPMD that ran efficiently on a cluster of two quad-core machines linked via a gigabit ethernet cable. Speedup of 6.2 and 5.7 times were achieved with 8 workers, over an un-parallelized code, for a 3 and 4 dimensional PBM respectively. Evaluations on work efficiency and scalability further affirm the algorithms’ respectable performance on larger clusters despite significant memory transfer overheads.