The resistance of PRESENT-80 against related-key differential attacks

We examine the security of the 64-bit lightweight block cipher PRESENT-80 against related-key differential attacks. With a computer search we are able to prove that for any related-key differential characteristic on full-round PRESENT-80, the probability of the characteristic only in the 64-bit state is not higher than 2−64. To overcome the exponential (in the state and key sizes) computational complexity of the search we use truncated differences, however as the key schedule is not nibble oriented, we switch to actual differences and apply early abort techniques to prune the tree-based search. With a new method called extended split approach we are able to make the whole search feasible and we implement and run it in real time. Our approach targets the PRESENT-80 cipher however,with small modifications can be reused for other lightweight ciphers as well.

Known and chosen key differential distinguishers for block ciphers

In this paper we investigate the differential properties of block ciphers in hash function modes of operation. First we show the impact of differential trails for block ciphers on collision attacks for various hash function constructions based on block ciphers. Further, we prove the lower bound for finding a pair that follows some truncated differential in case of a random permutation. Then we present open-key differential distinguishers for some well known round-reduced block ciphers.

Arabidopsis Rho-Related GTPases: Differential Gene Expression in Pollen and Polar Localization in Fission Yeast1

The Rho small GTP-binding proteins are versatile, conserved molecular switches in eukaryotic signal transduction. Plants contain a unique subfamily of Rho-GTPases called Rop (Rho-related GTPases from plants). Our previous studies involving injection of antibodies indicated that the pea Rop GTPase Rop1Ps is critical for pollen tube growth. In this study we show that overexpression of an apparent Arabidopsis ortholog of Rop1Ps, Rop1At, induces isotropic cell growth in fission yeast (Schizosaccharomyces pombe) and that green fluorescence protein-tagged Rop1At displays polar localization to the site of growth in yeast. We found that Rop1At and two other Arabidopsis Rops, Rop3At and Rop5At, are all expressed in mature pollen. All three pollen Rops fall into the same subgroup as Rop1Ps and diverge from those Rops that are not expressed in mature pollen, suggesting a coupling of the structural conservation of Rop GTPases to their gene expression in pollen. However, pollen-specific transcript accumulation for Rop1At is much higher than that for Rop3At and Rop5At. Furthermore, Rop1At is specifically expressed in anthers, whereas Rop3At and Rop5At are also expressed in vegetative tissues. In transgenic plants containing the Rop1At promoter:GUS fusion gene, GUS is specifically expressed in mature pollen and pollen tubes. We propose that Rop1At may play a predominant role in the regulation of polarized cell growth in pollen, whereas its close relatives Rop3At and Rop5At may be functionally redundant to Rop1At in pollen.

Low probability differentials and the cryptanalysis of full-round CLEFIA-128

So far, low probability differentials for the key schedule of block ciphers have been used as a straightforward proof of security against related-key differential analysis. To achieve resistance, it is believed that for cipher with k-bit key it suffices the upper bound on the probability to be 2− k . Surprisingly, we show that this reasonable assumption is incorrect, and the probability should be (much) lower than 2− k . Our counter example is a related-key differential analysis of the well established block cipher CLEFIA-128. We show that although the key schedule of CLEFIA-128 prevents differentials with a probability higher than 2− 128, the linear part of the key schedule that produces the round keys, and the Feistel structure of the cipher, allow to exploit particularly chosen differentials with a probability as low as 2− 128. CLEFIA-128 has 214 such differentials, which translate to 214 pairs of weak keys. The probability of each differential is too low, but the weak keys have a special structure which allows with a divide-and-conquer approach to gain an advantage of 27 over generic analysis. We exploit the advantage and give a membership test for the weak-key class and provide analysis of the hashing modes. The proposed analysis has been tested with computer experiments on small-scale variants of CLEFIA-128. Our results do not threaten the practical use of CLEFIA.

对低轮AES-256的相关密钥-不可能差分密码分析

研究AES-256抵抗相关密钥-不可能差分密码分析的能力.首先给出相关密钥的差分,该差分可以扩展到8轮(甚至更多轮)子密钥差分;然后构造出一个5.5轮的相关密钥不可能差分特征.最后,给出一个对7轮AES-256的攻击和4个对8轮AES-256的攻击.

Truncated differential analysis of reduced-round LBlock

In this paper we present truncated differential analysis of reduced-round LBlock by computing the differential distribution of every nibble of the state. LLR statistical test is used as a tool to apply the distinguishing and key-recovery attacks. To build the distinguisher, all possible differences are traced through the cipher and the truncated differential probability distribution is determined for every output nibble. We concatenate additional rounds to the beginning and end of the truncated differential distribution to apply the key-recovery attack. By exploiting properties of the key schedule, we obtain a large overlap of key bits used in the beginning and final rounds. This allows us to significantly increase the differential probabilities and hence reduce the attack complexity. We validate the analysis by implementing the attack on LBlock reduced to 12 rounds. Finally, we apply single-key and related-key attacks on 18 and 21-round LBlock, respectively.

Harmonising procurement policy environment - identifying key themes towards the development of a conceptual model

Capital works procurement and its regulatory policy environment within a country can be complex entities. For example, by virtue of Australia’s governmental division between the Commonwealth, states and local jurisdictions and the associated procurement networks and responsibilities at each level, the tendering process is often convoluted. There are four inter-related key themes identified in the literature in relation to procurement disharmony, including decentralisation, risk & risk mitigation, free trade & competition, and tendering costs. This paper defines and discusses these key areas of conflict that adversely impact upon the business environments of industry through a literature review, policy analysis and consultation with capital works procurement stakeholders. The aim of this national study is to identify policy differences between jurisdictions in Australia, and ascertain whether those differences are a barrier to productivity and innovation. This research forms an element of a broader investigation with an aim of developing efficient, effective and nationally harmonised procurement systems. Keywords: capital works, procurement policy reform Acknowledgement: The research described in this paper carried out by the Australian Cooperative Research Centre for Construction Innovation.

Automating computational proofs for public-key-based key exchange

We present an approach to automating computationally sound proofs of key exchange protocols based on public-key encryption. We show that satisfying the property called occultness in the Dolev-Yao model guarantees the security of a related key exchange protocol in a simple computational model. Security in this simpler model has been shown to imply security in a Bellare {Rogaway-like model. Furthermore, the occultness in the Dolev-Yao model can be searched automatically by a mechanisable procedure. Thus automated proofs for key exchange protocols in the computational model can be achieved. We illustrate the method using the well-known Lowe-Needham-Schroeder protocol.

Experimental evidence of heparanase, Hsp70 and NF-κB gene expression on the response of anti-inflammatory drugs in TNBS-induced colonic inflammation

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Key determinants of organisational silence for non-standard workers

Purpose – The purpose of this paper is to identify the key determinants of organisational silence from the perspective of non-standard workers (NSWs). The study focuses on three research themes: first, analysing the experiences motivating NSWs to remain silent; second, analysing the role of the NSW life cycle in the motivation to remain silent, the final theme is evaluation of the impact on organisational voice of an organisation employing a workforce in which NSWs and standard workers (SWs) are blended. Design/methodology/approach – The study utilises a phenomenological approach, as defined by Van Manen (2007), to collect and analyse the phenomenon of organisational silence from the perspective of NSWs. The NSWs are defined as individuals operating via Limited Liability UK registered companies created for the purpose of delivering services to organisations via a contract of services. This study employed a combination of phenomenology and hermeneutics to collect and analyse the data collected from the NSWs using semi-structured interviews (Lindseth and Norberg, 2004). Findings – The study concludes with three core findings. NSWs experience similar motivational factors to silence as experienced by standard workers (SWs). The key differential between a SW and a NSW is the role of defensive silence as a dominant motivator for a start-up NSW. The study identified that the reasons for this is that new NSWs are defensive to protect their reputation for any future contract opportunities. In addition, organisations are utilising the low confidence of new start up NSWs to suppress the ability of NSWs to voice. The research indicates how experienced NSWs use the marketing stage of their life cycle to establish voice mechanisms. The study identified that NSWs, fulfiling management and supervisory roles for organisations, are supporting/creating climates of silence through their transfer of experiences as SWs prior to becoming NSWs. Research limitations/implications – This study is a pilot study, and the findings from this study will be carried forward into a larger scale study through engagement with further participants across a diverse range of sectors. This study has identified that there is a need for further studies on organisational silence and NSWs to analyse more fully the impact of silence on the individuals and the organisation itself. A qualitative phenomenological hermeneutical study is not intended to be extrapolated to provide broad trends. The focus of the phenomenological hermeneutic research methodology is on describing and analysing the richness and depth of the NSW’s experiences of silence in organisational settings. Originality/value – This paper draws together the studies of worker classification, motivators for organisational silence, and the impact of blending SWs and NSWs in an organisational setting. The study demonstrates that academic research to date has focused predominantly on SWs to the exclusion of the 1.5 million, and growing, NSWs in the UK. This study examines these under-represented workers to analyse the participants’ experiences of organisational silence, and its consequences in organisational settings, demonstrating a need for further studies.

An examination of factors influencing ERP key-user satisfaction: A qualitative case study

Several companies are trying to improve their operation efficiency by implementing an enterprise resource planning (ERP) system that makes it possible to control the resources of the company in real time. However, the success of the implementation project is not a foregone conclusion; a significant part of these projects end in a failure, one way or another. Therefore it is important to investigate ERP system implementation more closely in order to increase understanding about factors influencing ERP system success and to improve the probability of a successful ERP implementation project. Consequently, this study was initiated because a manufacturing case company wanted to review the success of their ERP implementation project. To be exact, the case company hoped to gain both information about the success of the project and insight for future implementation improvement. This study investigated ERP success specifically by examining factors that influence ERP key-user satisfaction. User satisfaction is one of the most commonly applied indicators of information system success. The research data was mainly collected by conducting theme interviews. The subjects of the interviews were six key-users of the newly implemented ERP system. The interviewees were closely involved in the implementation project. Furthermore, they act as representative users that utilize the new system in everyday business processes. The collected data was analyzed by thematizing. Both data collection and analysis were guided by a theoretical frame of reference. This frame was based on previous research on the subject. The results of the study aligned with the theoretical framework to large extent. The four principal factors influencing key-user satisfaction were change management, contractor service, key-user’s system knowledge and characteristics of the ERP product itself. One of the most significant contributions of the research is that it confirmed the existence of a connection between change management and ERP key-user satisfaction. Furthermore, it discovered two new sub-factors influencing contractor service related key-user satisfaction. In addition, the research findings indicated that in order to improve the current level of key-user satisfaction, the case company should pay special attention to system functionality improvement and enhancement of the key-users’ knowledge. During similar implementation projects in the future, it would be important to assure the success of change management and contractor service related processes.

Security evaluation of Rakaposhi Stream Cipher

Rakaposhi is a synchronous stream cipher, which uses three main components: a non-linear feedback shift register (NLFSR), a dynamic linear feedback shift register (DLFSR) and a non-linear filtering function (NLF). NLFSR consists of 128 bits and is initialised by the secret key K. DLFSR holds 192 bits and is initialised by an initial vector (IV). NLF takes 8-bit inputs and returns a single output bit. The work identifies weaknesses and properties of the cipher. The main observation is that the initialisation procedure has the so-called sliding property. The property can be used to launch distinguishing and key recovery attacks. The distinguisher needs four observations of the related (K,IV) pairs. The key recovery algorithm allows to discover the secret key K after observing 29 pairs of (K,IV). Based on the proposed related-key attack, the number of related (K,IV) pairs is 2(128 + 192)/4 pairs. Further the cipher is studied when the registers enter short cycles. When NLFSR is set to all ones, then the cipher degenerates to a linear feedback shift register with a non-linear filter. Consequently, the initial state (and Secret Key and IV) can be recovered with complexity 263.87. If DLFSR is set to all zeros, then NLF reduces to a low non-linearity filter function. As the result, the cipher is insecure allowing the adversary to distinguish it from a random cipher after 217 observations of keystream bits. There is also the key recovery algorithm that allows to find the secret key with complexity 2 54.

Examining the effectiveness of Police-Citizens Youth Clubs on crime prevention and community safety

PCYCs, individually and as a whole, are highly valued in communities across Queensland. Participants in this evaluation identified numerous benefits of PCYCs, including: providing structured low-cost activities for young people and other community groups; developing positive relationships and trust between young people and police; developing young people into effective citizens; providing a safe place for young people and a hub for whole communities; addressing disadvantages faced by young people; and fostering social inclusion. Depending on the particular activities and programs delivered by a branch, PCYCs have the capacity to minimise risk factors and enhance protective factors relating to young people’s involvement in crime. For example, PCYCs can play an important role in strengthening young people’s engagement with education and family. However, the crime prevention and community safety aims of PCYCs, and measures that might work towards these aims are not widely- or well-understood, or appreciated, by those working in and with PCYCs. The key recommendation of this evaluation is therefore that the crime prevention and community safety aims of PCYCs in Queensland need to be better articulated, understood and reflected in the practice of those working in and with PCYCs. A related key finding is that many of the activities and programs currently provided by PCYCs could be better oriented towards the goals of crime prevention and community safety without major resource implications.

卫星激光通信Ⅰ链路和终端技术

卫星激光通信具有巨大的潜在应用价值, 国际上已实现高码率、小型化、轻量化和低功耗激光通信终端, 全文的第一部分即“链路和终端技术”综述了卫星激光通信的国外进展, 介绍了终端的关键技术, 讨论了终端设计思想。第二部分(另文)将讨论和介绍卫星激光通信终端地面检测和验证技术。