Construction of MDS Matrices from Generalized Feistel Structures

This paper investigates the construction of MDS matrices with generalized Feistel structures (GFS). The approach developed by this paper consists in deriving MDS matrices from the product of several sparser ones. This can be seen as a generalization to several matrices of the recursive construction which derives MDS matrices as the powers of a single companion matrix. The first part of this paper gives some theoretical results on the iteration of GFS. In second part, using GFS and primitive matrices, we propose some types of sparse matrices that are called extended primitive GFS (EGFS) matrices. Then, by applying binary linear functions to several round of EGFS matrices, lightweight $4\times 4$, $6\times 6$ and $8\times 8$ MDS matrices are proposed which are implemented with $67$, $156$ and $260$ XOR for $8$-bit input, respectively. The results match the best known lightweight $4\times 4$ MDS matrix and improve the best known $6\times 6$ and $8\times 8$ MDS matrices. Moreover, we propose $8\times 8$ Near-MDS matrices such that the implementation cost of the proposed matrices are $108$ and $204$ XOR for 4 and $8$-bit input, respectively. Although none of the presented matrices are involutions, the implementation cost of the inverses of the proposed matrices is equal to the implementation cost of the given matrices. Furthermore, the construction presented in this paper is relatively general and can be applied for other matrix dimensions and finite fields as well

A New Approach for the Implementation of Binary Matrices Using SLP Applications

In this paper, we propose a method for implementing binary matrices with low-cost XOR. First, using a random-iterative method, we obtain a list S from a binary matrix A. Then, based on the list S, we construct a binary matrix B. Next, we find a relation between the implementations of A and B. In other words, using the implementation of the matrix B, we get a low-cost implementation for the matrix A. Also, we show that the implementation of an MDS matrix M is associated with the form of the binary matrix used to construct the binary form of M. In addition, we propose a heuristics algorithm to implement MDS matrices. The best result of this paper is the implementation of a 8 × 8 involutory MDS matrix over 8-bit words with 408 XOR gates. The Paar algorithm is used as an SLP application to obtain implementations of this paper

Jump index in T-functions for designing a new basic structure of stream ciphers

The stream ciphers are a set of symmetric algorithms that receive a secret message as a sequence of bits and perform an encryption operation using a complex function based on key and IV, and combine xor with bit sequences. One of the goals in designing stream ciphers is to obtain a minimum period, which is one of the primary functions of using T-functions. On the other hand, the use of jump index in the design of LFSRs has made the analysis of LFSR-based stream ciphers more complicated. In this paper, we have tried to introduce a new method for designing the initial functions of stream ciphers with the use of T-functions concepts and the use of jump indexes, that has the maximum period. This method is resist side-channel attacks and can be efficiently implemented in hardware for a wide range of target processes and platforms

Decoy Cell Viruria in Kidney Transplant Patients. Does it correlate with Renal Function?

Objective: BK virus (BKV) infection after kidney transplantation has been a topic of great interest in the recent decade. Prospective screening studies have revealed that BKVN is principally an early complication of renal transplantation occurring within the first post-transplant year in most cases. The aim of the present study was to observe the incidence of decoy cell viruria in renal transplant recipients. Furthermore, correlation of decoy cell viruria with graft function was assessed. Methods: This analytic cross-sectional study was conducted in the Transplant Center of Alzahra Hospital, Isfahan, Iran between Jun 2014 and June 2015. Clinical screening for polyomavirus infection was done by means of urine cytological evaluation for decoy cells. Urine samples were analyzed in three steps including 2-4 months after transplantation, three and six months later. Results: Thirty-three patients (22 male and 11 female) received kidney transplant from living donors. The average of patients' age was 41.9 +/- 12.83 (range: 20-63 years). Peritoneal and hemodialysis were used for 15.6% and 84.4% of recipients. The occurrence of decoy cell viruria at the time of enrollment, 3 and 6 months later was found in 18.2%, 10.7% and zero, respectively. Conclusion: As urine cytology is easy to perform and of low cost, it is a useful tool for the investigation of active polyoma virus infection. Moreover, the findings advocate that the presence of decoy cells along with high creatinine is a better indicator of the virus presence

Direct Construction of Recursive MDS Diffusion Layers using Shortened BCH Codes

MDS matrices allow to build optimal linear diffusion layers in block ciphers. However, MDS matrices cannot be sparse and usually have a large description, inducing costly software/hardware implementations. Recursive MDS matrices allow to solve this problem by focusing on MDS matrices that can be computed as a power of a simple companion matrix, thus having a compact description suitable even for constrained environ- ments. However, up to now, finding recursive MDS matrices required to perform an exhaustive search on families of companion matrices, thus limiting the size of MDS matrices one could look for. In this article we propose a new direct construction based on shortened BCH codes, al- lowing to efficiently construct such matrices for whatever parameters. Unfortunately, not all recursive MDS matrices can be obtained from BCH codes, and our algorithm is not always guaranteed to find the best matrices for a given set of parameters.Comment: Best paper award; Carlos Cid and Christian Rechberger. 21st International Workshop on Fast Software Encryption, FSE 2014, Mar 2014, London, United Kingdom. springe

P-wave indices as predictors of atrial fibrillation

Abstract Background P‐wave duration (PDURATION) and P‐wave area (PAREA) have been linked to risk of atrial fibrillation (AF), but they do not improve the efficacy of Framingham AF risk score. We suggest the incorporation of both variables in one index, the P‐wave area/P‐wave duration (PAREA/DURATION) index, which may be considered an expression of the average amplitude of the P wave that reflects aspects of P‐wave morphology. Objective To assess the prognostic value of P‐wave area/P‐wave duration index (PAREA/DURATION index) in lead II together with other P‐wave indices (PWIs) in incidence of AF in the Copenhagen Holter Study. Methods The study included 632 men and women, between 55 and 75 years with no apparent heart disease or AF. Baseline standard 12‐lead Electrocardiography (ECGs) were analyzed manually. Results The median follow‐up time was 14.7 (14.5;14.9) years. A total of 68 cases of AF and 233 cases of death were recorded. The restricted cubic spline method showed a U‐shaped association between PAREA/DURATION and rate of AF. The lowest quintile of PAREA/DURATION index in lead II was associated with increased rate of AF, HR 2.80 (1.64–4.79). The addition of the new index to the Framingham model for AF improved the model in this population. The PAREA in lead II in its lowest quintile was also associated with increased rate of AF, HR 2.16 (1.25–3.75), but did not improve the Framingham model. PDURATION and P‐wave terminal force (PTF) were not significantly associated with AF. Conclusion A flat P wave as expressed by a small PAREA/DURATION index in lead II is associated with increased rate of incident AF beyond known AF risk factors

New population-based exome data question the pathogenicity of some genetic variants previously associated with Marfan syndrome

BACKGROUND: Marfan syndrome (MFS) is a rare autosomal dominantly inherited connective tissue disorder with an estimated prevalence of 1:5,000. More than 1000 variants have been previously reported to be associated with MFS. However, the disease-causing effect of these variants may be questionable as many of the original studies used low number of controls. To study whether there are possible false-positive variants associated with MFS, four in silico prediction tools (SIFT, Polyphen-2, Grantham score, and conservation across species) were used to predict the pathogenicity of these variant. RESULTS: Twenty-three out of 891 previously MFS-associated variants were identified in the ESP. These variants were distributed on 100 heterozygote carriers in 6494 screened individuals. This corresponds to a genotype prevalence of 1:65 for MFS. Using a more conservative approach (cutoff value of >2 carriers in the EPS), 10 variants affected a total of 82 individuals. This gives a genotype prevalence of 1:79 (82:6494) in the ESP. A significantly higher frequency of MFS-associated variants not present in the ESP were predicted to be pathogenic with the agreement of ≥3 prediction tools, compared to the variants present in the ESP (p = 3.5 × 10(−15)). CONCLUSIONS: This study showed a higher genotype prevalence of MFS than expected from the phenotype prevalence in the general population. The high genotype prevalence suggests that these variants are not the monogenic cause of MFS. Therefore, caution should be taken with regard to disease stratification based on these previously reported MFS-associated variants