Provably Minimum Data Complexity Integral Distinguisher Based on Conventional Division Property

Division property is an effective method for finding integral distinguishers for block ciphers, performing cube attacks on stream ciphers, and studying the algebraic degree of boolean functions. One of the main problems in this field is how to provably find the smallest input multiset leading to a balanced output. In this paper, we propose a new method based on division property for finding integral distinguishers with a provably minimum data complexity on permutation functions and block ciphers, in the conventional division property model. The new method is based on efficiently analyzing the algebraic normal form of the target output boolean function. We examine the proposed method on LBlock, TWINE, SIMON, Present, Gift, and Clyde-128 block ciphers. Although in most cases, the results are compliant with the distinguishers reported in the previous work, the proposed method proves the optimality of these results, in the conventional division property model. However, the proposed method can find distinguishers for 8-round Clyde-128 with a data complexity less than the previously reported one, based on conventional division property. The new method is also capable of determining the maximum number of balanced output bits in an integral distinguisher with a specified number of active bits. We propose an algorithm to exploit this capability and apply it to the studied ciphers. As a result, we determine the maximum number of balanced bits on integral distinguishers with minimum and non-minimum data complexities on the studied ciphers and report improved results on Gift-64, Present and SIMON64 in the conventional model

Security Analysis of a Dynamic Threshold Secret Sharing Scheme Using Linear Subspace Method

A dealer-free and non-interactive dynamic threshold secret sharing scheme has been proposed by Harn et.al., in 2015. In this scheme, a (t; n) secret sharing scheme in secret reconstruction phase can turn into a (m; n) scheme in secret reconstruction phase, where m is the number of participanting shareholders. It has been claimed that the secrecy of shares and the secrecy of the secret are unconditionally preserved if $m \in (t; 1 + t(t + 1)=2]$. This paper provides a security analysis of this scheme in two directions. Firstly, we show that this scheme does not have the dynamic property, i.e. any t + 1 released values are sufficient to reconstruct the secret, even the agreed updated threshold is larger. Secondly, we show that any t + 1 released values are sufficient to forge the released value of a non-participating shareholder. The technique that we enjoyed for our analysis is the linear subspace method, which basically measures the information leaked by the known parameters of the scheme by computing the dimension of the linear subspace spanned by these parameter. This method has shown to be capable of cryptanalysis of some secret sharing based schemes, whose security relies on keeping the coefficients of the underlying polynomial(s) secret

Cryptanalysis and Improvement of a Flexible and Lightweight Group Authentication Scheme

Shamir’s secret sharing scheme is one of the substantial threshold primitives, based on which many security protocols are constructed such as group authentication schemes. Notwithstanding the unconditional security of Shamir\u27s secret sharing scheme, protocols that are designed based on this scheme do not necessarily inherit this property. In this work, we evaluate the security of a lightweight group authentication scheme, introduced for IoT networks in IEEE IoT Journal in 2020, and prove its weakness against the linear subspace attack, which is a recently-proposed cryptanalytical method for secret sharing-based schemes. Then, we propose an efficient and attack-resistant group authentication protocol for IoT networks

MILP-Based Automatic Differential Searches for LEA and HIGHT

In this paper we use MILP technique for automatic search for differential characteristics of ARX ciphers LEA and HIGHT. We show that the MILP model of the differential property of modular addition with one constant input can be represented with a much less number of linear inequalities compared to the general case. Benefiting from this new developed model for HIGHT block cipher, we can achieve a reduction of 112r out of 480r in the total number of linear constraints for MILP model of r-round of HIGHT. This saving accelerates the searching process of HIGHT about twice as fast. We enjoy the MILP model to investigate the differential effect of these ciphers and provide a more accurate estimation for the differential probability, as well. Our observations show that despite HIGHT, LEA exhibits a strong differential effect. The details of differential effects are reflected in a more compact manner using the newly defined notion of probability polynomial. The results gained by this method improve or extend the previous results as follows. For LEA block cipher, we found more efficient 12 and 13-round differentials whose probabilities are better than the best previous 12 and 13-round differentials for a factor of about 2^6 and 2^7, respectively. In the case of HIGHT block cipher, we found two new 12 and 13-round differentials, though with the same best reported probabilities

The aroma of TEMED as an activation and stabilizing signal for the antibacterial enzyme HEWL

The unpleasant smell released from dead bodies, may serve as an alarm for avoiding certain behaviour or as feeding or oviposition attractants for animals. However, little is known about their effect on the structure and function of proteins. Previously, we reported that using the aroma form of TEMED (a diamine), representative of the "smell of death", could completely inhibit the fibril formation of HEWL, as an antibacterial enzyme, and a model protein for fibrillation studies. To take this further, in this study we investigated the kinetics of TEMED using a number of techniques and in particular X-ray crystallography to identify the binding site(s) of TEMED and search for hotspot(s) necessary to inhibit fibril formation of HEWL. Structural data, coupled with other experimental data reported in this study, revealed that TEMED completely inhibited fibril formation and stabilized the structure of HEWL through enhancement of the CH-Π interaction and binding to an inhibitor hotspot comprised of residues Lys33, Phe34, Glu35 and Asn37 of HEWL. Additionally, results from this study showed that the binding of TEMED increased the activity and thermal stability of HEWL, helping to improve the function of this antibacterial enzyme. In conclusion, the role of the "smell of death", as an important signal molecule affecting the activity and stability of HEWL was greatly highlighted, suggesting that aroma producing small molecules can be signals for structural and functional changes in proteins

Synthesis of New Derivative of pyrazolo[4,5-b]quinoxaline Bearing imidazolidine-2,4-dione as a Potential Anticancer Agent

Introduction: Among heterocyclic anticancer compounds, quinoxalines and imidazolidine-2,4-dione are the most prominent since they constitute important classes of natural products and synthetic pharmaceuticals. In general, they are used as valuable intermediates and building blocks in pharmaceutical synthesis. Therefore, much attention has been paid to the synthesis of quinoxaline derivatives bearing imidazolidine-2,4-dione either by classic methods or by multicomponent reactions.  Methods and Results: The title compound was prepared through a three- step procedure. In the first step, equimolar amounts of D-glucose and o-phenylenediamine were reacted with phenyl hydrazine in the presence of acetic acid, to form the pyrazolo[4,5-b]quinoxaline  derivative. The second step involved oxidation of the resulted compound by use of sodium metaperioddate. Finally, the related aldehyde was condensed by imidazolidine-2,4-dione to yield the corresponding 3-alkylidene pyrazolo[4,5-b]quinoxaline . Conclusions: The procedure applied in this study established a convenient method for the preparation of the title compounds. The process was straight forward and it used abundant and readily available staring materials. Due to its chemical structure, and in particular the presence of the quinioxaline ring, which is a commonly encountered motif in compounds of medicinal interest, the prepared product is expected to show anticancer activity

New Automatic search method for Truncated-differential characteristics: Application to Midori, SKINNY and CRAFT

In this paper, using Mixed Integer Linear Programming, a new automatic search tool for truncated differential characteristic is presented. Our method models the problem of finding a maximal probability truncated differential characteristic, which is able to distinguish the cipher from a pseudo random permutation. Using this method, we analyse Midori64, SKINNY64/X and CRAFT block ciphers, for all of which the existing results are improved. In all cases, the truncated differential characteristic is much more efficient than the (upper bound of) bit-wise differential characteristic proven by the designers, for any number of rounds. More specifically, the highest possible rounds, for which an efficient differential characteristic can exist for Midori64, SKINNY64/X and CRAFT are 6, 7 and 10 rounds respectively, for which differential characteristics with maximum probabilities of $2^{-60}$, $2^{-52}$ and $2^{-62.61}$ (may) exist. Using our new method, we introduce new truncated differential characteristics for these ciphers with respective probabilities $2^{-54}$, $2^{-4}$ and $2^{-24}$ at the same number of rounds. Moreover, the longest truncated differential characteristics found for SKINNY64/X and CRAFT have 10 and 12 rounds, respectively. This method can be used as a new tool for differential analysis of SPN block ciphers

Multiuser Two-Way Filter-and-Forward Relaying for Ultra-Wideband Communications

Abstract-In this paper, a multiuser two-way filter-and-forward relaying scheme for wireless communication over wideband channels is considered. We propose pre/post-rake processing in conjunction with optimized filtering at the relay to reduce the signal processing burden at the source and destination nodes. Two relay filter design problem formulations are introduced, namely (a) a convex optimization problem formulation with closed-form solutions and (b) the more general case, which is a non-convex problem solvable via an alternating optimization algorithm. For both design alternatives widely linear formulations are devised. The presented numerical results demonstrate the capability of the proposed designs to establish reliable two-way communication links between nodes with limited signal processing power and in the absence of a direct link

IGD-ScoreChain: A Lightweight and Scalable Blockchain Based on Node Sharding for the Internet of Things

Due to the significant development of the intelligence industry worldwide, various initiatives have increasingly recognized the value of the Internet of Things (IoT). IoT systems, however, are often hin- dered by fundamental challenges, such as the need for a central server to manage them. Decentralizing these systems can be achieved through the use of blockchains. Recently, there has been an increase in the popularity of blockchain in various fields, such as banking, IoT, and the intelligence industry, and human societies have taken notice of it. One of the main problems is with the scalability of such systems as the network size grows. This paper examines how to overcome this challenge in blockchain-based IoT systems. We introduce a sharding-based blockchain that is lightweight and scalable. In the proposed method, the nodes are assigned to a number of shards based on their history of activity. As part of this study, the Improved Byzantine Fault Tolerance with Graceful performance Degradation (IGDBFT) consensus algorithm is introduced within the proposed scheme for intra-shard consensus. A solution to storing blocks and cross-shard transactions has been developed using a global chain containing parent blocks in the cloud layer. Finally, we analyze the security and efficiency of our scheme and compare our sharding-based protocol with previous protocols

The effect of descriptive evaluation of elementary school third grade subjects on academic achievement of students

The goal of this research was the effect of descriptive evaluation of elementary school third grade subjects on academic achievement of students and its comparison with traditional evaluation. The statistical population of the research included all female third grade students of elementary schools in ZarrinShahr in academic year of 2012-2013 who were a total number of 742 students as well as the elementary school third grade teachers who were a number of 34 teachers. Among them a number of 147 students and 28 teachers were selected via cluster sampling. Research methodology in this study was of survey-descriptive type. The research tools were checklists and a questionnaire of opinion toll, made by the researcher. To assess the validity of the tools used, the face validity and content validity were used and the validity of the questionnaire was estimated as a=0.93. Chi square test was used to analyze the research questions. The results of the research showed that using different methods of descriptive evaluation has been effective in improving the students’ performances in such subjects as the Holy Quran, social sciences, arts, science & Persian, while it has not been effective in improving their performances in such subjects as heavenly gifts (the Holy Quran for elementary students) and mathematics. Finally, the results of opinion toll showed that the teachers found descriptive evaluation more suitable than traditional evaluation in evaluating all the third grade subjects of elementary school. Keywords: Evaluation, Descriptive evaluation, Traditional evaluation, Students’ performances