Uniform First-Order Threshold Implementations

Most masking schemes used as a countermeasure against side-channel analysis attacks require an extensive amount of fresh random bits on the fly. This is burdensome especially for lightweight cryptosystems. Threshold implementations (TIs) that are secure against firstorder attacks have the advantage that fresh randomness is not required if the sharing of the underlying function is uniform. However, finding uniform realizations of nonlinear functions that also satisfy other TI properties can be a challenging task. In this paper, we discuss several methods that advance the search for uniformly shared functions for TIs. We focus especially on three-share implementations of quadratic functions due to their low area footprint. Our methods have low computational complexity even for 8-bit Boolean functions

Constructing TI-Friendly Substitution Boxes Using Shift-Invariant Permutations

The threat posed by side channels requires ciphers that can be efficiently protected in both software and hardware against such attacks. In this paper, we proposed a novel Sbox construction based on iterations of shift-invariant quadratic permutations and linear diffusions. Owing to the selected quadratic permutations, all of our Sboxes enable uniform 3-share threshold implementations, which provide first order SCA protections without any fresh randomness. More importantly, because of the shift-invariant property, there are ample implementation trade-offs available, in software as well as hardware. We provide implementation results (software and hardware) for a four-bit and an eight-bit Sbox, which confirm that our constructions are competitive and can be easily adapted to various platforms as claimed. We have successfully verified their resistance to first order attacks based on real acquisitions. Because there are very few studies focusing on software-based threshold implementations, our software implementations might be of independent interest in this regard

Systems and methods for altering visual acuity

Provided are systems operable to effect a temporary change in a modulation transfer function (MTF) of a target imaging system. The systems include a light source operable to produce light for transient propagation onto at least a portion of the target imaging system, a power source in operative communication with the light source and configured to effect the production of light from the light source, and a transmission unit in operative communication with the light source and configured to propagate the produced light onto at least a portion of the target imaging system. The propagated light is configured for absorbance by the portion of the target imaging system; the absorbance causes an increase in temperature and a change in a refractive index profile of at least the portion of the imaging system. The change in refractive index profile produces a temporary change in the MTF of the imaging system.Board of Regents, University of Texas Syste

One-bit Distributed Sensing and Coding for Field Estimation in Sensor Networks

This paper formulates and studies a general distributed field reconstruction problem using a dense network of noisy one-bit randomized scalar quantizers in the presence of additive observation noise of unknown distribution. A constructive quantization, coding, and field reconstruction scheme is developed and an upper-bound to the associated mean squared error (MSE) at any point and any snapshot is derived in terms of the local spatio-temporal smoothness properties of the underlying field. It is shown that when the noise, sensor placement pattern, and the sensor schedule satisfy certain weak technical requirements, it is possible to drive the MSE to zero with increasing sensor density at points of field continuity while ensuring that the per-sensor bitrate and sensing-related network overhead rate simultaneously go to zero. The proposed scheme achieves the order-optimal MSE versus sensor density scaling behavior for the class of spatially constant spatio-temporal fields.Comment: Fixed typos, otherwise same as V2. 27 pages (in one column review format), 4 figures. Submitted to IEEE Transactions on Signal Processing. Current version is updated for journal submission: revised author list, modified formulation and framework. Previous version appeared in Proceedings of Allerton Conference On Communication, Control, and Computing 200

Setting reference level in the human safety guidelines via nerve activation intercomparison at IF

International guidelines/standards have been published for human protection from electromagnetic field exposure. The research in the intermediate frequencies (IF: 300 Hz-10 MHz) is scattered unlike for other frequencies, and thus the limit prescribed in the guidelines/standards are different by a factor of 10. The IEEE International Committee on Electromagnetic Safety has published a research agenda for exploring the electrostimulation thresholds. However, the consistency of the excitation models for specific target tissue needs to be revised. For this purpose, we present the first intercomparison study using multiphysics modelling to investigate stimulation thresholds during transcranial magnetic stimulation (TMS). To define the stimulation threshold, a noninvasive technique for brain stimulation has been used. In this study, by incorporating individual neurons into electromagnetic computation in realistic head models, stimulation thresholds can be determined. The study case of one subject showed that the allowable external magnetic field strength in the current guidelines/standard is conservative

A Study of Deep Learning Robustness Against Computation Failures

For many types of integrated circuits, accepting larger failure rates in computations can be used to improve energy efficiency. We study the performance of faulty implementations of certain deep neural networks based on pessimistic and optimistic models of the effect of hardware faults. After identifying the impact of hyperparameters such as the number of layers on robustness, we study the ability of the network to compensate for computational failures through an increase of the network size. We show that some networks can achieve equivalent performance under faulty implementations, and quantify the required increase in computational complexity

Threshold Implementations with Non-Uniform Inputs

Modern block ciphers designed for hardware and masked with Threshold Implementations (TIs) provide provable security against first-order attacks. However, the application of TIs leaves designers to deal with a trade-off between its security and its cost, for example, the process to generate its required random bits. This generation cost comes with an increased overhead in terms of area and latency. Decreasing the number of random bits for the masking allows to reduce the aforementioned overhead. We propose to reduce the randomness to mask the secrets, like the plaintext. For that purpose, we suggest relaxing the requirement for the uniformity of the input shares and reuse randomness for their masking in first-order TIs. We apply our countermeasures to first-order TIs of the Prince and Midori64 ciphers with three shares. Since the designs with non-uniform masks are no longer perfect first-order probing secure, we provide further analysis by calculating bounds on the advantage of a noisy threshold-probing adversary. We then make use of the PROLEAD tool, which implements statistical tests verifying the robust probing security to compare its output with our estimates. Finally, we evaluate the designs on FPGA to highlight the practical security of our solution. We observe that their security holds while requiring four times less randomness over uniform TIs