Preventing Scan-Based Side-Channel Attacks by Scan Obfuscating with a Configurable Shift Register

Scan test is widely used in integrated circuit test. However, the excellent observability and controllability provided by the scan test gives attackers an opportunity to obtain sensitive information by using scan design to threaten circuit security. Hence, the primary motivation of this paper is to improve the existing DFT technique, i.e., to enhance the chip security on the premise of guaranteeing test quality. In this paper, we propose a new scan design method against scan-based side-channel attack. In the proposed method, the encryption structure is adopted, which requires the correct test authorization code to carry out normal test operation. Without the correct test authorization, the attackers cannot obtain the desired scan data, preventing the scan-based side-channel attacks. Furthermore, the test authorization code is determined by the nonvolatile memory built into the chip to realize the inconsistency of the test authorization code for each chip.

geospatial analysis of pertussis and its risk factors in southern Ontario from 2005–2016

Introduction: Pertussis, commonly known as whooping cough, is a bacterial respiratory tract infection caused by Bordetella pertussis. Pertussis affects more than 48 million people worldwide annually, most of whom are under the age of 5. Hypothesis & Objectives: The hypothesis being investigated is that pertussis incidence, between 2005 and 2016, is not equally distributed across public health units in southern Ontario. We aim to identify disease cluster locations and associate geospatial fluctuations in incidence rates with putative risk factors. Materials and Methods: Data was sourced from Public Health Ontario on pertussis incidence in southern Ontario for all ages, specifically for each public health unit’s geographical area. A choropleth map was generated using data smoothed by empirical Bayesian estimation in a spatial analysis context. Following the creation of an incidence map for southern Ontario, the spatial scan test was applied to elucidate the existence of any disease clusters at a public health unit level. Moran’s I was used to determine whether there was evidence of any spatial dependence in pertussis incidence. Finally, putative risk factors were assessed in Poisson regression models and spatial Poisson regression models as potential predictor variables. Results and Discussion: The flexible spatial scan test identified three spatial clusters where incidence rates of pertussis were higher than expected. A spatial Poisson regression model was fit that included predictor variables of socioeconomic status and population density. For every 100 people/km2 increase in population density there was a significant 6% increase in pertussis incidence (p=0.03). Interestingly, vaccination rates were not found to be predictive of pertussis incidence nor did the variable improve the model. This epidemiological study identifies where pertussis incidence is clustered and what variables it is associated with, both of which are valuable for public health purposes and as a reference for future research into pertussis.

Comparison of the Aerosol Photometer and Light Scattering Airborne Particle Counter (LSAPC) Methods for Installed Filter System Leak Testing

The installed filter system leak test method for cleanrooms and clean zones is described in ISO 14644-3, Cleanrooms and associated controlled environments—Part 3: Test method. Portions of the methods in ISO 14644-3 were adapted from IEST-RP-CC034.4[Schaumburg, Illinois, US: Institute of Environmental Science and Technology], which provides a set of recommended procedures for leak testing HEPA and ULPA filters in situ (in the field) with the aerosol photometer test method and the light scattering airborne particle counter (LSAPC) test method. Leak testing is performed to confirm that the final high efficiency air filter system is properly installed by verifying the absence of bypass leakage in the installation, and that the filters are free of defects (small holes and other damage in the filter medium, frame, seal and leaks in the filter bank framework). This study was conducted to compare the aerosol photometer and LSAPC methods. Testing in the study consisted of creating artificial leaks in the filter system, measuring the upstream and downstream concentrations with the aerosol photometer and with the LSAPC, and comparing the filter leak penetration results. Comparison testing was applied to the procedure for the installed terminal panel filter system leakage scan test (stationary measurement) and the procedure for evaluating overall leakage of high-airflow box-type filters mounted in a duct or air-handling unit (AHU) (overall leakage test). It was found that the aerosol photometer and the LSAPC gave similar results for filter leakage within experimental error. The comparison of the leakage scan tests (stationary measurement) showed that the penetration calculated for the channel ≥ 0.3 μm of the LSAPC with an air flow rate of 1cu ft/min (CFM) (28.3 l/min) was very similar to the penetration measured with the aerosol photometer for a leakage level >0.01 % of the upstream concentration. The comparison result of the overall leakage test showed that overall total penetration values, obtained after dilution of artificial calibrated leaks in the filter media, were identical, within the measurement uncertainty, for particles ≥0.3 μm whether the sampling rate of the LSAPC was 1 CFM (28.3 l/min) or 50 l/min. Several recommendations are provided. In particular, for filters mounted in a duct or AHU where the filter function is critical, the recommended method is the leakage scan test method, using a grid sampling method in a plane downstream of the filter (as agreed between customer and supplier).