Investigating knowledge management factors affecting Chinese ICT firms performance: An integrated KM framework

This is an Author's Accepted Manuscript of an article published in the Journal of Information Systems Management, 28(1), 19 - 29, 2011, copyright Taylor & Francis, available online at: http://www.tandfonline.com/10.1080/10580530.2011.536107.This article sets out to investigate the critical factors of Knowledge Management (KM) which are considered to have an impact on the performance of Chinese information and communication technology (ICT) firms. This study confirms that the cultural environment of an enterprise is central to its success in the context of China. It shows that a collaborated, trusted, and learning environment within ICT firms will have a positive impact on their KM performance

Legislative History: An Act Concerning the Operation of Emergency Medical Vehicles (SP482)(LD 1303)

https://digitalmaine.com/legishist114/2302/thumbnail.jp

Implementing Lightweight Block Ciphers on x86 Architectures

Abstract. Lightweight block ciphers are designed so as to fit into very constrained environments, but usually not really with software performance in mind. For classical lightweight applications where many constrained devices communicate with a server, it is also crucial that the cipher has good software performance on the server side. Recent work has shown that bitslice implementations applied to Piccolo and PRESENT led to very good software speeds, thus making lightweight ciphers interesting for cloud applications. However, we remark that bitslice implementations might not be interesting for some situations, where the amount of data to be enciphered at a time is usually small, and very little work has been done on non-bitslice implementations. In this article, we explore general software implementations of lightweight ciphers on x86 architectures, with a special focus on LED, Piccolo and PRESENT. First, we analyze table-based implementations, and we provide a theoretical model to predict the behavior of various possible trade-offs depending on the processor cache latency profile. We obtain the fastest table-based implementations for our lightweight ciphers, which is of interest for legacy processors. Secondly, we apply to our portfolio of primitives the vperm implementation trick for 4-bit Sboxes, which gives good performance, extra side-channels protection, and is quite fit for many lightweight primitives. Finally, we investigate bitslice implementations, analyzing various costs which are usually neglected (bitsliced form (un)packing, key schedule, etc.), but that must be taken in account for many lightweight applications. We finally discuss which type of implementation seems to be the best suited depending on the applications profile

Universal Forgery and Multiple Forgeries of MergeMAC and Generalized Constructions

This article presents universal forgery and multiple forgeries against MergeMAC that has been recently proposed to fit scenarios where bandwidth is limited and where strict time constraints apply. MergeMAC divides an input message into two parts, $m\|\tilde{m}$, and its tag is computed by $\mathcal{F}( \mathcal{P}_1(m) \oplus \mathcal{P}_2(\tilde{m}) )$, where $\mathcal{P}_1$ and $\mathcal{P}_2$ are PRFs and $\mathcal{F}$ is a public function. The tag size is 64 bits. The designers claim $64$-bit security and imply a risk of accepting beyond-birthday-bound queries. This paper first shows that it is inevitable to limit the number of queries up to the birthday bound, because a generic universal forgery against CBC-like MAC can be adopted to MergeMAC. Afterwards another attack is presented that works with a very few number of queries, 3 queries and $2^{58.6}$ computations of $\mathcal{F}$, by applying a preimage attack against weak $\mathcal{F}$, which breaks the claimed security. The analysis is then generalized to a MergeMAC variant where $\mathcal{F}$ is replaced with a one-way function $\mathcal{H}$. Finally, multiple forgeries are discussed in which the attacker\u27s goal is to improve the ratio of the number of queries to the number of forged tags. It is shown that the attacker obtains tags of $q^2$ messages only by making $2q-1$ queries in the sense of existential forgery, and this is tight when $q^2$ messages have a particular structure. For universal forgery, tags for $3q$ arbitrary chosen messages can be obtained by making $5q$ queries

MILP-based Differential Attack on Round-reduced GIFT

At Asiacrypt 2014, Sun et al. proposed a MILP model to search for differential characteristics of bit-oriented block ciphers. In this paper, we improve this model to search for differential characteristics of GIFT, a new lightweight block cipher proposed at CHES 2017. GIFT has two versions, namely GIFT-64 and GIFT-128. For GIFT-64, we find the best 12-round differential characteristic and a number of iterative 4-round differential characteristics with our MILP-based model. We give a key-recovery attack on 19-round GIFT-64. For GIFT-128, we find a 18-round differential characteristic and give the first attack on 22-round GIFT-128

Generic Attack on Iterated Tweakable FX Constructions

International audienceTweakable block ciphers are increasingly becoming a common primitive to build new resilient modes as well as a concept for multiple dedicated designs. While regular block ciphers define a family of permutations indexed by a secret key, tweakable ones define a family of permutations indexed by both a secret key and a public tweak. In this work we formalize and study a generic framework for building such a tweakable block cipher based on regular block ciphers, the iterated tweakable FX construction, which includes many such previous constructions of tweakable block ciphers. Then we describe a cryptanal-ysis from which we can derive a provable security upper-bound for all constructions following this tweakable iterated FX strategy. Concretely, the cryptanalysis of r rounds of our generic construction based on n-bit block ciphers with κ-bit keys requires O(2 r r+1 (n+κ)) online and offline queries. For r = 2 rounds this interestingly matches the proof of the particular case of XHX2 by Lee and Lee (ASIACRYPT 2018) thus proving for the first time its tightness. In turn, the XHX and XHX2 proofs show that our generic cryptanalysis is information theoretically optimal for 1 and 2 rounds

A General Framework for the Related-key Linear Attack against Block Ciphers with Linear Key Schedules

We present a general framework for the related-key linear attack that can be applied to iterative block ciphers with linear key schedules. The attack utilizes a newly introduced related-key linear approximation that is obtained directly from a linear trail. The attack makes use of a known related-key data consisting of triplets of a plaintext, a ciphertext, and a key difference such that the ciphertext is the encrypted value of the plaintext under the key that is the xor of the key to be recovered and the specified key difference. If such a block cipher has a linear trail with linear correlation \epsilon, it admits attacks with related-key data of size \epsilon^{-2} just as in the case of classical Matsui\u27s Algorithms. But since the attack makes use of a related-key data, the attacker can use a linear trail with the squared correlation less than 2^{-n}, n being the block size, in case the key size is larger than n. Moreover, the standard key hypotheses seem to be appropriate even when the trail is not dominant as validated by experiments. The attack can be applied in two ways. First, using a linear trail with squared correlation smaller than 2^{-n}, one can get an effective attack covering more rounds than existing attacks against some ciphers, such as Simon48/96, Simon64/128 and Simon128/256. Secondly, using a trail with large squared correlation, one can use related-key data for key recovery even when the data is not suitable for existing linear attacks

On a Generalization of Substitution-Permutation Networks: The HADES Design Strategy

Keyed and unkeyed cryptographic permutations often iterate simple round functions. Substitution-permutation networks (SPNs) are an approach that is popular since the mid 1990s. One of the new directions in the design of these round functions is to reduce the substitution (S-Box) layer from a full one to a partial one, uniformly distributed over all the rounds. LowMC and Zorro are examples of this approach. A relevant freedom in the design space is to allow for a highly non-uniform distribution of S-Boxes. However, choosing rounds that are so different from each other is very rarely done, as it makes security analysis and implementation much harder. We develop the design strategy Hades and an analysis framework for it, which despite this increased complexity allows for security arguments against many classes of attacks, similar to earlier simpler SPNs. The framework builds upon the wide trail design strategy, and it additionally allows for security arguments against algebraic attacks, which are much more of a concern when algebraically simple S-Boxes are used. Subsequently, this is put into practice by concrete instances and benchmarks for a use case that generally benefits from a smaller number of S-Boxes and showcases the diversity of design options we support: A candidate cipher natively working with objects in GF(p), for securing data transfers with distributed databases using secure multiparty computation (MPC). Compared to the currently fastest design MiMC, we observe significant improvements in online bandwidth requirements and throughput with a simultaneous reduction of preprocessing effort, while having a comparable online latency