Linearization of Multi-valued Nonlinear Feedback Shift Registers

The Linearization of Nonlinear feedback shift registers (NFSRs) is to find their state transition matrices. In this paper, we investigate the linearization multi-valued NFSRs by considering it as a logical network via a semi-tensor product approach. A new state transition matrix is found for an multi-valued NFSR, which can be simply computed from the truth table of its feedback function, and the new state transition matrix is easier to compute and is more explicit. First, a linear representation of a multi-valued NFSR is given, based on which several necessary and sufficient conditions for the nonsingularity are given. Then, some properties of the state transition matrice are provided, which are helpful to theoretically analyze NFSRs. Finally, we give properties of a maximum length multi-valued NFSR and the linear representation of the general structure of an n-bit shift register with updating functions

On the Nonsingularity and Equivalence of NFSRs

Nonlinear feedback shift registers (NFSRs) are used in many stream ciphers as their main building blocks. In particular, Galois NFSRs with terminal bits are used in the typical stream ciphers Grain and Trivium. One security criterion for the design of stream ciphers is to assure their used NFSRs are nonsingular. The nonsingularity is well solved for Fibonacci NFSRs, whereas it is not for Galois NFSRs. In addition, some types of Galois NFSRs equivalent to Fibonacci ones have been found. However, whether there exist new types of such Galois NFSRs remains unknown. The paper first considers the nonsingularity of Galois NFSRs. Some necessary/sufficient conditions are presented. The paper then concentrates on the equivalence between Galois NFSRs and Fibonacci ones. Some necessary conditions for Galois NFSRs equivalent to Fibonacci ones are provided. The Galois NFSRs with terminal bits equivalent to a given Fibonacci one are enumerated. Moreover, two classes of nonsingular Galois NFSRs with terminal bits are found to be the new types of Galois NFSRs equivalent to Fibonacci ones

A Generic Method for Investigating Nonsingular Galois NFSRs

Let n be a positive integer. An n-stage Galois NFSR has n registers and each register is updated by a feedback function. Then a Galois NFSR is called nonsingular if every register generates (strictly) periodic sequences, i.e., no branch points. In this paper, a generic method for investigating nonsingular Galois NFSRs is provided. Two fundamental concepts that are standard Galois NFSRs and the simplified feedback function of a standard Galois NFSR are proposed. Based on the new concepts, a sufficient condition is given for nonsingular Galois NFSRs. In particular, for the class of Galois NFSRs with linear simplified feedback functions, a necessary and sufficient condition is presented. Hopefully, some new insights are provided on determining nonsingular Galois NFSRs

Side-Channel Analysis of Keymill

One prominent countermeasure against side-channel attacks, especially differential power analysis (DPA), is fresh re-keying. In such schemes, the so-called re-keying function takes the burden of protecting a cryptographic primitive against DPA. To ensure the security of the scheme against side-channel analysis, the used re-keying function has to withstand both simple power analysis (SPA) and differential power analysis (DPA). Recently, at SAC 2016, Keymill---a side-channel resilient key generator (or re-keying function)---has been proposed, which is claimed to be inherently secure against side-channel attacks. In this work, however, we present a DPA attack on Keymill, which is based on the dynamic power consumption of a digital circuit that is tied to the $0\rightarrow1$ and $1\rightarrow0$ switches of its logical gates. Hence, the power consumption of the shift-registers used in Keymill depends on the $0\rightarrow1$ and $1\rightarrow0$ switches of its internal state. This information is sufficient to obtain the internal differential pattern (up to a small number of bits, which have to be brute-forced) of the 4 shift-registers of Keymill after the nonce (or $IV$) has been absorbed. This leads to a practical key-recovery attack on Keymill

Secure Channel Coding Schemes based on Polar Codes

In this paper, we propose two new frameworks for joint encryption encoding schemes based on polar codes, namely efficient and secure joint secret/public key encryption channel coding schemes. The issue of using new coding structure, i.e. polar codes in McEliece-like and RN-like schemes is addressed. Cryptanalysis methods show that the proposed schemes have an acceptable level of security with a relatively smaller key size in comparison with the previous works. The results indicate that both schemes provide an efficient error performance and benefit from a higher code rate which can approach the channel capacity for large enough polar codes. The most important property of the proposed schemes is that if we increase the block length of the code, we can have a higher code rate and higher level of security without significant changes in the key size of the scheme. The resulted characteristics of the proposed schemes make them suitable for high-speed communications, such as deep space communication systems

Social Entrepreneurship:Societal Wealth Creation Under Conditions of Near-Knightian Uncertainty

In this dissertation I examine the emergent phenomenon of social entrepreneurship through the lens of the structure of entrepreneurial payoffs under conditions of near-Knightian uncertainty. Current theory assumes entrepreneurs will respond to a new form of incentive, beyond the pursuits of wealth, power, and prestige. It also assumes that productive entrepreneurship can result from a shift in the structure of payoffs. I examine four for-profit social entrepreneurial experiments executed in Southern Africa in order to enhance understanding of the question: "What recurring challenges do for-profit social entrepreneurs face in attempting to restructure payoffs under conditions of near-Knightian uncertainty?" My data are drawn from field observations, company archival records, email communications, and unique targeted interventions designed to solve vexing challenges which arose in the course of the experiments. The dissertation makes several contributions. First, it uncovers several new insights from my findings which should inform future research in for-profit social enterprises. Second, it sheds light on enterprise creation under conditions of near-Knightian uncertainty. Third, it introduces a framework for understanding the challenges faced by nonsingular objective firms, and proposes that lack of success in the creation of such firms is not necessarily failure – there are multiple levels of success that are part of an Aspirations Cascade, the highest efficiency being delivered by the social impact enterprise and the lowest efficiency achieved from direct charity

International Conference on Computer Science and Communication Engineering

UBT Annual International Conference is the 8th international interdisciplinary peer reviewed conference which publishes works of the scientists as well as practitioners in the area where UBT is active in Education, Research and Development. The UBT aims to implement an integrated strategy to establish itself as an internationally competitive, research-intensive university, committed to the transfer of knowledge and the provision of a world-class education to the most talented students from all background. The main perspective of the conference is to connect the scientists and practitioners from different disciplines in the same place and make them be aware of the recent advancements in different research fields, and provide them with a unique forum to share their experiences. It is also the place to support the new academic staff for doing research and publish their work in international standard level. This conference consists of sub conferences in different fields like: – Computer Science and Communication Engineering– Management, Business and Economics– Mechatronics, System Engineering and Robotics– Energy Efficiency Engineering– Information Systems and Security– Architecture – Spatial Planning– Civil Engineering , Infrastructure and Environment– Law– Political Science– Journalism , Media and Communication– Food Science and Technology– Pharmaceutical and Natural Sciences– Design– Psychology– Education and Development– Fashion– Music– Art and Digital Media– Dentistry– Applied Medicine– Nursing This conference is the major scientific event of the UBT. It is organizing annually and always in cooperation with the partner universities from the region and Europe. We have to thank all Authors, partners, sponsors and also the conference organizing team making this event a real international scientific event. Edmond Hajrizi, President of UBTUBT – Higher Education Institutio