Algebraic analysis of Trivium-like ciphers

Trivium is a bit-based stream cipher in the final portfolio of the eSTREAM project. In this paper, we apply the approach of Berbain et al. to Trivium-like ciphers and perform new algebraic analyses on them, namely Trivium and its reduced versions: Trivium-N, Bivium-A and Bivium-B. In doing so, we answer an open question in the literature. We demonstrate a new algebraic attack on Bivium-A. This attack requires less time and memory than previous techniques which use the F4 algorithm to recover Bivium-A's initial state. Though our attacks on Bivium-B, Trivium and Trivium-N are worse than exhaustive keysearch, the systems of equations which are constructed are smaller and less complex compared to previous algebraic analysis. Factors which can affect the complexity of our attack on Trivium-like ciphers are discussed in detail

Schizophrenia-like psychosis and aceruloplasminemia

Schizophrenia-like illnesses occur in a variety of medical and neurological conditions but to date have not been described in association with aceruloplasminemia. Aceruloplasminemia is an autosomal recessive disorder of iron metabolism which leads to iron deposition in the basal ganglia, thalamus, cerebellum and hippocampus and which usually presents in middle age with extrapyramidal symptoms and dementia. We describe a 21-year-old woman on treatment for aceruloplasminemia who presented with schizophrenia-like psychosis and declining function in the absence of neurological signs. Neuropsychological testing showed significant dominant hemisphere deficits. Magnetic resonance imaging showed bilateral iron deposition in the cerebellar dentate nuclei and thalami, frontal atrophy, and periventricular white matter hyperintensities. Functional imaging suggested global hypoperfusion. The clinical, cognitive and imaging findings were not typical for either aceruloplasminemia or schizophrenia alone and the possible relationship between the two disorders is discussed with particular reference to implications for our understanding of schizophrenia

A Viable LoRa Framework for Smart Cities

This research is intended to provide practical insights to empower designers, developers and management to develop smart cities underpinned by Long Range (LoRa) technology. LoRa, one of most prevalent long-range wireless communication technologies, can be used to underpin the development of smart cities. This study draws upon relevant research to gain an understanding of underlying principles and issues involved in the design and management of long-range and low-power networks such as LoRa. This research uses empirical evidence that has been gathered through experiments with a LoRa network to analyse network design and identify challenges and then proposes cost-effective and timely solutions. Particularly, practical measurements of LoRa network dependencies and performance metrics are used to support our proposals. This research identifies a number of network performance metrics that need to be considered and controlled when designing and managing LoRa- specific networks from the perspectives of hardware, software, networking and security

Migrating to Post-Quantum Cryptography: a Framework Using Security Dependency Analysis

Quantum computing is emerging as an unprecedented threat to the current state of widely used cryptographic systems. Cryptographic methods that have been considered secure for decades will likely be broken, with enormous impact on the security of sensitive data and communications in enterprises worldwide. A plan to migrate to quantum-resistant cryptographic systems is required. However, migrating an enterprise system to ensure a quantum-safe state is a complex process. Enterprises will require systematic guidance to perform this migration to remain resilient in a post-quantum era, as many organisations do not have staff with the expertise to manage this process unaided. This paper presents a comprehensive framework designed to aid enterprises in their migration. The framework articulates key steps and technical considerations in the cryptographic migration process. It makes use of existing organisational inventories and provides a roadmap for prioritising the replacement of cryptosystems in a post-quantum context. The framework enables the efficient identification of cryptographic objects, and can be integrated with other frameworks in enterprise settings to minimise operational disruption during migration. Practical case studies are included to demonstrate the utility and efficacy of the proposed framework using graph theoretic techniques to determine and evaluate cryptographic dependencies.Comment: 21 Page

Differential Random Fault Attacks on certain CAESAR Stream Ciphers (Supplementary Material)

This document contains supplementary material to the paper with the same title available from the proceedings of the International Conference on Information Security and Cryptology (ICISC) 2019. In this supplementary material, we demonstrate that the random fault attack strategy described in the full paper can be applied to ciphers in the MORUS family, resulting in partial state recovery for these ciphers

State convergence and keyspace reduction of the Mixer stream cipher

This paper presents an analysis of the stream cipher Mixer, a bit-based cipher with structural components similar to the well-known Grain cipher and the LILI family of keystream generators. Mixer uses a 128-bit key and 64-bit IV to initialise a 217-bit internal state. The analysis is focused on the initialisation function of Mixer and shows that there exist multiple key-IV pairs which, after initialisation, produce the same initial state, and consequently will generate the same keystream. Furthermore, if the number of iterations of the state update function performed during initialisation is increased, then the number of distinct initial states that can be obtained decreases. It is also shown that there exist some distinct initial states which produce the same keystream, resulting in a further reduction of the effective key space

Tweaking Generic OTR to Avoid Forgery Attacks

This paper considers the security of the Offset Two-Round (OTR) authenticated encryption mode \cite{cryptoeprint:2013:628} with respect to forgery attacks. The current version of OTR gives a security proof for specific choices of the block size $(n)$ and the primitive polynomial used to construct the finite field $\mathbb{F}_{2^n}$. Although the OTR construction is generic, the security proof is not. For every choice of finite field the distinctness of masking coefficients must be verified to ensure security. In this paper, we show that some primitive polynomials result in collisions among the masking coefficients used in the current instantiation, from which forgeries can be constructed. We propose a new way to instantiate OTR so that the masking coefficients are distinct in every finite field $\mathbb{F}_{2^n}$, thus generalising OTR without reducing the security of OTR