Kalikinkar Mandal

WG-8 : A Lightweight Stream Cipher for Resource-Constrained Smart Devices

Lightweight cryptographic primitives are essential for securing pervasive embedded devices like RFID tags, smart cards, and wireless sensor nodes. In this paper, we present a lightweight stream cipher WG-8, which is tailored from the well-known Welch-Gong (WG) stream cipher family, for resource-constrained devices. WG-8 inherits the good randomness and cryptographic properties of the WG stream cipher family and is resistant to the most common attacks against stream ciphers. The software implementations of the WG-8 stream cipher on two popular low-power microcontrollers as well as the extensive comparison with other lightweight cryptography implementations highlight that in the context of securing lightweight embedded applications WG-8 has favorable performance and low energy consumption.

A New Approach to Fast Near-Optimal Channel Assignment in Cellular Mobile Networks

This paper presents a novel method for solving channel assignment problems (CAPs) in hexagonal cellular networks with nonhomogeneous demands in a 2-band buffering system (where channel interference does not extend beyond two cells). The CAP with nonhomogeneous demand is first partitioned into a sequence of smaller subproblems, each of which has a homogeneous demand from a subset of the nodes of the original network. Solution to such a subproblem constitutes an assignment phase, where multiple homogeneous demands are assigned to the nodes corresponding to the subproblem, satisfying all the frequency separation constraints. The whole assignment process for the original network consists of a succession of multiple homogeneous assignments for all the subproblems. Based on this concept, we present a polynomial time approximation algorithm for solving the CAP for cellular networks having nonhomogeneous demands. Our proposed assignment algorithm, when executed on well-known benchmark instances, comes up with an assignment which is always within about 6 percent more than the optimal bandwidth, but requires a very small execution time (less than 5 millisecond on a HPxw8400 workstation). The proposed algorithm is very much suitable for real-life situations, where fast channel assignment is of primary importance, tolerating, however, a marginal deviation (6 percent) from the optimal bandwidth.

Cryptographically Strong de Bruijn Sequences with Large Periods

In this paper we first refine Mykkeltveit et al.’s technique for producing de Bruijn sequences through compositions. We then conduct an analysis on an approximation of the feedback functions that generate de Bruijn sequences. The cycle structures of the approximated feedback functions and the linear complexity of a sequence produced by an approximated feedback function are determined. Furthermore, we present a compact representation of an (n + 16)-stage nonlinear feedback shift register (NLFSR) and a few examples of de Bruijn sequences of period 2 n , 35 ≤ n ≤ 40, which are generated by the recursively constructed NLFSR together with the evaluation of their implementation.

Design and Implementation of Warbler Family of Lightweight Pseudorandom Number Generators for Smart Devices

With the advent of ubiquitous computing and the Internet of Things (IoT), the security and privacy issues for various smart devices such as radio-frequency identification (RFID) tags and wireless sensor nodes are receiving increased attention from academia and industry. A number of lightweight cryptographic primitives have been proposed to provide security services for resource-constrained smart devices. As one of the core primitives, a cryptographically secure pseudorandom number generator (PRNG) plays an important role for lightweight embedded applications. The most existing PRNGs proposed for smart devices employ true random number generators as a component, which generally incur significant power consumption and gate count in hardware. In this article, we present Warbler family, a new pseudorandom number generator family based on nonlinear feedback shift registers (NLFSRs) with desirable randomness properties. The design of the Warbler family is based on the combination of modified de Bruijn blocks together with a nonlinear feedback Welch-Gong (WG) sequence generator, which enables us to precisely characterize the randomness properties and to flexibly adjust the security level of the resulting PRNG. Some criteria for selecting parameters of the Warbler family are proposed to offer the maximum level of security. Two instances of the Warbler family are also described, which feature two different security levels and are dedicated to EPC C1 Gen2 RFID tags and wireless sensor nodes, respectively. The security analysis shows that the proposed instances not only can pass the cryptographic statistical tests recommended by the EPC C1 Gen2 standard and NIST but also are resistant to the cryptanalytic attacks such as algebraic attacks, cube attacks, time-memory-data tradeoff attacks, Mihaljević et al.’s attacks, and weak internal state and fault injection attacks. Our ASIC implementations using a 65nm CMOS process demonstrate that the proposed two lightweight instances of the Warbler family can achieve good performance in terms of speed and area and provide ideal solutions for securing low-cost smart devices.

Optimal parameters for the WG stream cipher family

A general structure of the Welch-Gong (WG) stream cipher family is based on filtering an m-sequence of degree l over a finite field

sLiSCP: Simeck-Based Permutations for Lightweight Sponge Cryptographic Primitives

\ensuremath{{\mathbb{F}}}_{2^m}

Despicable me(ter): Anonymous and fine-grained metering data reporting with dishonest meters

where the filtering function is a WG transformation from

Filtering Nonlinear Feedback Shift Registers using Welch-Gong Transformations for Securing RFID Applications

\ensuremath{{\mathbb{F}}}_{2^m}

WG-8: A Lightweight Stream Cipher for Resource-Constrained Smart Devices

to

Generating Good Span n Sequences Using Orthogonal Functions in Nonlinear Feedback Shift Registers

\ensuremath{{\mathbb{F}}}_{2}