Security Against Hardware Trojan Attacks Using Key-Based Design Obfuscation

Malicious modification of hardware in untrusted fabrication facilities, referred to as hardware Trojan, has emerged as a major security concern. Comprehensive detection of these Trojans during post-manufacturing test has been shown to be extremely difficult. Hence, it is important to develop design techniques that provide effective countermeasures against hardware Trojans by either preventing Trojan attacks or facilitating detection during test. Obfuscation is a technique that is conventionally employed to prevent piracy of software and hardware intellectual property (IP). In this work, we propose a novel application of key-based circuit structure and functionality obfuscation to achieve protection against hardware Trojans triggered by rare internal circuit conditions. The proposed obfuscation scheme is based on judicious modification of the state transition function, which creates two distinct functional modes: normal and obfuscated. A circuit transitions from the obfuscated to the normal mode only upon application of a specific input sequence, which defines the key. We show that it provides security against Trojan attacks in two ways: (1) it makes some inserted Trojans benign, i.e. they become effective only in the obfuscated mode; and (2) it prevents an adversary from exploiting the true rare events in a circuit to insert hard-to-detect Trojans. The proposed design methodology can thus achieve simultaneous protection from hardware Trojans and hardware IP piracy. Besides protecting ICs against Trojan attacks in foundry, we show that it can also protect against malicious modifications by untrusted computer-aided design (CAD) tools in both SoC and FPGA design flows. Simulation results for a set of benchmark circuits show that the scheme is capable of achieving high levels of security against Trojan attacks at modest area, power and delay overhead.     

Tie-line constrained distributed state estimation

This paper presents an implementable distributed state estimation method for online analysis of power systems having multiple, geographically separated areas. Distributed state estimation apart from giving a faster solution, also improves the condition number of the resultant gain matrices. The method proposed here uses the conventional WLS estimator (Gauss-Newton method) with equality constraints forcing the tie line flows as calculated by the adjacent areas to be equal. Based on the topology of the network, the system is partitioned into multiple areas and a processor is assigned to each of these areas for solving the local state estimation problem. Simulations carried out on the IEEE 14, 30 and 118 bus systems show good convergence properties and improvement on the condition number of the gain matrices when compared with centralized algorithms.     

Optimal placement of PMU and SCADA measurements for security constrained state estimation

This paper presents a method for the use of Supervisory Control and Data Acquisition (SCADA) and synchronized measurements for complete observability of a power system. Under normal operation, both Node Phasor Measurement Unit (NPMU) and SCADA measurements are optimally placed using integer programming and Genetic Algorithm (GA) respectively. The minimum condition number of the Jacobian matrix is used as a criteria in conjunction with GA to obtain a completely determined condition. Next, a triangular factorization approach is used to search for the necessary candidates for single branch outage and single/multiple measurement loss. These candidate measurements are optimized by the binary integer programming method. Numerical results on the IEEE test systems are demonstrated. The results clearly show the robustness of the method to obtain reliable measurements under both normal and contingency conditions.     

Lewis acid–base properties of cellulose acetate phthalate‐polycaprolactonediol blend by inverse gas chromatography

The net retention volumes, V_N, of n‐alkanes and five polar probes are determined on cellulose acetate phthalate–polycaprolactonediol blend column by inverse gas chromatography in the temperature range 323.15–363.15 K. The dispersive surface energy, $\gamma _{\bf S}^{\bf d}$ , of the blend has been calculated using the V_N values of n‐alkanes and the $\gamma _{\bf S}^{\bf d}$ at 333.15 K is 12.6 mJ/m². The $\gamma _{\bf S}^{\bf d}$ values are decreasing linearly with increase of temperature. The V_N values of the five polar solutes are used to calculate the specific component of the enthalpy of adsorption, ${\Delta }{H}_{\bf a}^{\bf S}$ . The Lewis acid–base parameters, K_a and K_b, are derived using ${\bf \Delta }{H}_{\bf a}^{\bf S}$ values and are found to be 0.019 and 0.403, respectively. The K_a and K_b values indicate that the blend surface contain more basic sites and interact strongly with the acidic probes. The acid–base parameters have been used to analyze the preferential interaction of the solid surface with acidic and basic probes. POLYM. ENG. SCI., 2013. © 2013 Society of Plastics Engineers     

Effect of sexual abstinence on the proportion of X-bearing sperm as assessed by multicolor fluorescent in situ hybridization

OBJECTIVE: To document the relation between sexual abstinence and the proportion of X-bearing sperm in the ejaculate. DESIGN: Prospective cohort study. SETTING: Medical college. PATIENT(S): Ten normospermic men, aged 30 to 40 years, provided two semen samples: the first sample was obtained 1.0 to 1.5 days after ejaculation; the second, 7 to 10 days after ejaculation. INTERVENTION(S): Abstinence. MAIN OUTCOME MEASURE(S): Proportion of X- and Y-bearing sperm in two ejaculates. RESULT(S): Multicolor fluorescent in situ hybridization using directly labeled alpha-satellite probes specific for chromosomes 18, X and Y were used to analyze 40,273 sperm. After 1.0 to 1.5 days of abstinence, there were 47.6% +/- 1.7% (mean +/- SD) X-bearing sperm, and after 7 to 10 days of abstinence, there were 49.6% +/- 2.1% X-bearing sperm. The X:Y ratio increased marginally from 0.905 to 0.981. CONCLUSION(S): Sexual abstinence marginally increases the proportion of X-bearing sperm in the ejaculate as assessed by multicolor fluorescent in situ hybridization. This change of borderline statistical significance probably has little impact on the secondary sex ratio.     

Heavy metal pollution in a sewage-fed lake of Bhopal, (M. P.) India

Shahpura Lake receives untreated domestic sewage from residential areas in Bhopal city. Analysis of water, plankton, fish and sediment reveals that the lake is contaminated by certain heavy metals. The concentrations of some of these metals including iron and manganese were within acceptable limits, whereas others including chromium, nickel, zinc and lead were not within acceptable water quality limits. Metal concentrations in the sewage inlet drain and lake sediment were compared with published criteria. The comparison revealed that the metals in the sediment ranged from the ‘non‐polluted’ to the ‘heavy pollution’ categories. The reference dose was calculated by the adoption of the United States Environmental Protection Agency reference dose factor, and the result reveals that the local population is not exposed to undue health risks. Concentrations of heavy metals in the water increased during the second year of the study, indicating an increase in the pollution load on the system. This might increase the bioaccumulation levels in fish and increase the actual dose of metals to which the local population will be exposed.     

The contagious nature of imprisonment: an agent-based model to explain racial disparities in incarceration rates

We build an agent-based model of incarceration based on the susceptible–infected–suspectible (SIS) model of infectious disease propagation. Our central hypothesis is that the observed racial disparities in incarceration rates between Black and White Americans can be explained as the result of differential sentencing between the two demographic groups. We demonstrate that if incarceration can be spread through a social influence network, then even relatively small differences in sentencing can result in large disparities in incarceration rates. Controlling for effects of transmissibility, susceptibility and influence network structure, our model reproduces the observed large disparities in incarceration rates given the differences in sentence lengths for White and Black drug offenders in the USA without extensive parameter tuning. We further establish the suitability of the SIS model as applied to incarceration by demonstrating that the observed structural patterns of recidivism are an emergent property of the model. In fact, our model shows a remarkably close correspondence with California incarceration data. This work advances efforts to combine the theories and methods of epidemiology and criminology.     

Enhanced hydroformylation by carbon dioxide‐expanded media with soluble Rh complexes in nanofiltration membrane reactors

A novel process for continuous hydroformylation in CO₂‐expanded liquids (CXLs) is demonstrated using bulky phosphite ligands that are effectively retained in the stirred reactor by a nanofiltration membrane. The reactor is operated at 50°C with a syngas pressure of 0.6 MPa to avoid CO inhibition of reaction rate and selectivity. The nanofiltration pressure is provided by ～3.2 MPa CO₂ that expands the hydroformylation mixture and increases the H₂/CO ratio in the CXL phase resulting in enhanced turnover frequency (～340 h^?1), aldehydes selectivity (>90%) and high regioselectivity (n/i ～8) at nearly steady operation. The use of pressurized CO₂ also reduces the viscosity in the CXL phase, thereby improving the mass‐transfer properties. Constant permeate flux is maintained during the 50 h run with Rh leakage being less than 0.5 ppm. This technology concept has potential applications in homogeneous catalytic processes to improve resource utilization and catalyst containment for practical viability. © 2013 American Institute of Chemical Engineers AIChE J, 59: 4287–4296, 2013