114 research outputs found

    Mitigating smart card fault injection with link-time code rewriting: a feasibility study

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    We present a feasibility study to protect smart card software against fault-injection attacks by means of binary code rewriting. We implemented a range of protection techniques in a link-time rewriter and evaluate and discuss the obtained coverage, the associated overhead and engineering effort, as well as its practical usability

    Synthesis and Reactions of Iron and Ruthenium Dinitrogen Complexes

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    This thesis is primarily concerned with the synthesis and reactions of iron and ruthenium dinitrogen complexes of tripodal phosphine ligands. Of particular interest is the cationic dinitrogen bridged iron complex [(FeH(PP3))2(μ-N2)]2+ 23, containing the tetradentate ligand P(CH2CH2PMe2)3, PP3 1, and its potential for facilitating the reduction of the bound dinitrogen upon treatment with acid. The synthesis of a selection of novel and known tripodal phosphine and amino phosphine ligands is described. New ligands N(CH2CH2CH2PMe2)3 N3P3 7 and P(CH2CH2CH2PiPr2)3 P3Pi3 11 were synthesised by nucleophilic displacement of bromide from the bromoalkylphosphine and bromoalkylamine precursors with the relevant phosphide. A new method for synthesis of known ligand P(CH2CH2CH2PMe2)3 P3P3 19 by the nucleophilic substitution of its chloroalkylphosphine oxide with dimethylphosphide and subsequent reduction is also reported. The reaction of [(FeH(PP3))2(μ-N2)]2+ 23 with base produced the singly deprotonated mixed valence species [(FeH(PP3))(μ-N2)(Fe(PP3))]+ 37 and subsequently the iron(0) dinuclear species (Fe(PP3))2(μ-N2) 38 and mononuclear complex Fe(N2)(PP3) 44. The 15N labelling of complexes has allowed the 15N NMR spectra of 23, 37 and 44 to be reported along with the observation of a long-range 5JP-P coupling across the bridging dinitrogen of 37. Complexes 23 and 37 were also structurally characterised by X-ray crystallography. The treatment of a variety of iron PP3 1 dinitrogen complexes, including the mononuclear species [(Fe(N2)H(PP3)]+ 22, with acid, or base then acid, did not result in the formation of ammonia from reduction of the complexed dinitrogen. The reactions of FeCl2(PP3) 24 and FeClH(PP3) 25 with ammonia and hydrazine afforded the complexes [FeCl(N2H4)(PP3)] 48, [FeH(N2H4)(PP3)] 47, [FeCl(NH3)(PP3)] 49 and [FeH(NH3)(PP3)] 46. Complexes 47 and 46 are considered potential intermediates in any reduction of the dinitrogen ligand of 23 to ammonia. Complexes 49 and 46 were also formed from the decomposition of the hydrazine complexes 48 and 47. The 15N NMR shifts, derived from both the 15N labelling of complexes and from 1H-15N 2D NMR experiments at natural abundance are reported. In addition, complex 47 was characterised by X-ray crystallography. The novel ligand P(CH2CH2PiPr2)3 PPi3 12 was used in the successful synthesis of [FeCl(PPi3)]+ 51 and [RuCl(PPi3)]+ 56. Reduction of 51 and 56 with potassium graphite under dinitrogen afforded the complexes Fe(N2)(PPi3) 52 and Ru(N2)(PPi3) 57 respectively. This is the first report of a Ru(0) dinitrogen complex. Treatment of 52 and 57 with lutidinium tetrafluoroborate resulted in protonation and oxidation of the metal centre to afford the hydrido complexes [Fe(N2)H(PPi3)]+ 53 and [Ru(N2)H(PPi3)]+ 58 respectively. 15N labelled analogues of 52, 53, 57 and 58 were achieved by exchange reactions with 15N2 gas, allowing for analysis by 15N NMR spectroscopy. Species 52, 57 and 58 have also been structurally characterised by X-ray crystallography. Treatment of 52 with excess acid in THF afforded both 53 and the dihydrogen complex [Fe(H2)H(PPi3)]+ 54. The mechanism of formation of 54 probably involves the C-H activation of the solvent THF. The complex cation [RuCl(P3Pi3)]+ 65 was synthesised using the novel ligand P3Pi3 11. A polymeric iron(II) complex, [Fe2Cl4(N3P3)2]n 66, of the tridentate ligand N3P3 7 was also synthesised. Characterisation of both 65 and 66 by X-ray crystallography is reported. (FeCl)2(μ-Cl)2(μ-Pi2)2 68, an unusual bridged dimer of the known ligand CH2(PiPr2)2 Pi2 67, and iron(II) and iron(0) tetramers of the PP3 1 ligand, namely [Fe4Cl4(PP3)5]4+ 71 and Fe4(PP3)5 72 were also characterised by X-ray crystallography

    Morphological evidences indicate that the interference of cimetidine on the peritubular components is responsible for detachment and apoptosis of Sertoli cells

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    Cimetidine, referred as antiandrogenic agent, has caused alterations in the seminiferous tubules, including alterations in the peritubular tissue and death of myoid cells by apoptosis. Regarding the structural and functional importance of the peritubular tissue for the maintenance of Sertoli cells (SC), we purpose to investigate the SC-basement membrane interface, focusing the morphological features of SC and their interaction with the basement membrane in the affected tubules by cimetidine. Ten animals were distributed into two groups, control (CG) and cimetidine (CmG) which received saline solution and 50 mg of cimetidine per kg of body weight, respectively, for 52 days. The testes were fixed, dehydrated and embedded for analyses under light and transmission electron microscopy. Paraffin sections were submitted to the TUNEL method; sections of testes embedded in glycol methacrylate were submitted to PAS method and stained by H&E for morphological and quantitative analyses of Sertoli Cells. In the CmG, the SC nuclei were positive to the TUNEL method and showed typical morphological alterations of cell death by apoptosis (from early to advanced stages). A significant reduction in the number of Sertoli Cells was probably due to death of these cells by apoptosis. A close relationship between SC nuclear alterations (including a high frequency of dislocated nuclei from the basal portion) and damage in the peritubular tissue was observed. The ultrastructural analysis showed a parallelism between the gradual advancement of apoptotic process in SC and detachment of the anchoring sites (hemidesmosomes) of SC plasma membrane from the lamina densa. The presence of portions of lamina densa underlying the detached hemidesmosomes indicates a continuous deposition of lamina densa, resulting in the thickening of the basal lamina. The results indicate a possible disarrangement of the SC cytoskeleton, including the focal adhesion structure. These alterations are related to SC apoptosis and probably result from disturbs induced by cimetidine on the peritubular tissue

    The Randomized Slicer for CVPP: Sharper, Faster, Smaller, Batchier

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    Following the recent line of work on solving the closest vector problem with preprocessing (CVPP) using approximate Voronoi cells, we improve upon previous results in the following ways:-We derive sharp asymptotic bounds on the success probability of the randomized slicer, by modelling the behaviour of the algorithm as a random walk on the coset of the lattice of the target vector. We thereby solve the open question left by Doulgerakis–Laarhoven–De Weger [PQCrypto 2019] and Laarhoven [MathCrypt 2019].-We obtain better trade-offs for CVPP and its generalisations (strictly, in certain regimes), both with and without nearest neighbour searching, as a direct result of the above sharp bounds on the success probabilities.-We show how to reduce the memory requirement of the slicer, and in particular the corresponding nearest neighbour data structures, using ideas similar to those proposed by Becker–Gama–Joux [Cryptology ePrint Archive, 2015]. Using 20.185d+o(d)memory, we can solve a single CVPP instance in 20.264d+o(d)time.-We further improve on the per-instance time complexities in certain memory regimes, when we are given a sufficiently large batch of CVPP problem instances for the same lattice. Using memory, we can heuristically solve CVPP instances in amortized time, for batches of size at least.Our random walk model for analysing arbitrary-step transition probabilities in complex step-wise algorithms may be of independent interest, both for deriving analytic bounds through convexity arguments, and for computing optimal paths numerically with a shortest path algorithm. As a side result we apply the same random walk model to graph-based nearest neighbour searching, where we improve upon results of Laarhoven [SOCG 2018] by deriving sharp bounds on the success probability of the corresponding greedy search procedure

    Cryptanalysis of GlobalPlatform Secure Channel Protocols

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    GlobalPlatform (GP) card specifications are the de facto standards for the industry of smart cards. Being highly sensitive, GP specifications were defined regarding stringent security requirements. In this paper, we analyze the cryptographic core of these requirements; i.e. the family of Secure Channel Protocols (SCP). Our main results are twofold. First, we demonstrate a theoretical attack against SCP02, which is the most popular protocol in the SCP family. We discuss the scope of our attack by presenting an actual scenario in which a malicious entity can exploit it in order to recover encrypted messages. Second, we investigate the security of SCP03 that was introduced as an amendment in 2009. We find that it provably satisfies strong notions of security. Of particular interest, we prove that SCP03 withstands algorithm substitution attacks (ASAs) defined by Bellare et al. that may lead to secret mass surveillance. Our findings highlight the great value of the paradigm of provable security for standards and certification, since unlike extensive evaluation, it formally guarantees the absence of security flaws

    Targeted disruption of Slc2a8 (GLUT8) reduces motility and mitochondrial potential of spermatozoa

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    GLUT8 is a class 3 sugar transport facilitator which is predominantly expressed in testis and also detected in brain, heart, skeletal muscle, adipose tissue, adrenal gland, and liver. Since its physiological function in these tissues is unknown, we generated a Slc2a8 null mouse and characterized its phenotype. Slc2a8 knockout mice appeared healthy and exhibited normal growth, body weight development and glycemic control, indicating that GLUT8 does not play a significant role for maintenance of whole body glucose homeostasis. However, analysis of the offspring distribution of heterozygous mating indicated a lower number of Slc2a8 knockout offspring (30.5:47.3:22.1%, Slc2a8+/+, Slc2a8+/−, and Slc2a8−/− mice, respectively) resulting in a deviation (p = 0.0024) from the expected Mendelian distribution. This difference was associated with lower ATP levels, a reduced mitochondrial membrane potential and a significant reduction of sperm motility of the Slc2a8 knockout in comparison to wild-type spermatozoa. In contrast, number and survival rate of spermatozoa were not altered. These data indicate that GLUT8 plays an important role in the energy metabolism of sperm cells

    Reticular synthesis and the design of new materials

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    The long-standing challenge of designing and constructing new crystalline solid-state materials from molecular building blocks is just beginning to be addressed with success. A conceptual approach that requires the use of secondary building units to direct the assembly of ordered frameworks epitomizes this process: we call this approach reticular synthesis. This chemistry has yielded materials designed to have predetermined structures, compositions and properties. In particular, highly porous frameworks held together by strong metal-oxygen-carbon bonds and with exceptionally large surface area and capacity for gas storage have been prepared and their pore metrics systematically varied and functionalized.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/62718/1/nature01650.pd

    The LifeCycle Project-EU Child Cohort Network : a federated analysis infrastructure and harmonized data of more than 250,000 children and parents

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    Early life is an important window of opportunity to improve health across the full lifecycle. An accumulating body of evidence suggests that exposure to adverse stressors during early life leads to developmental adaptations, which subsequently affect disease risk in later life. Also, geographical, socio-economic, and ethnic differences are related to health inequalities from early life onwards. To address these important public health challenges, many European pregnancy and childhood cohorts have been established over the last 30 years. The enormous wealth of data of these cohorts has led to important new biological insights and important impact for health from early life onwards. The impact of these cohorts and their data could be further increased by combining data from different cohorts. Combining data will lead to the possibility of identifying smaller effect estimates, and the opportunity to better identify risk groups and risk factors leading to disease across the lifecycle across countries. Also, it enables research on better causal understanding and modelling of life course health trajectories. The EU Child Cohort Network, established by the Horizon2020-funded LifeCycle Project, brings together nineteen pregnancy and childhood cohorts, together including more than 250,000 children and their parents. A large set of variables has been harmonised and standardized across these cohorts. The harmonized data are kept within each institution and can be accessed by external researchers through a shared federated data analysis platform using the R-based platform DataSHIELD, which takes relevant national and international data regulations into account. The EU Child Cohort Network has an open character. All protocols for data harmonization and setting up the data analysis platform are available online. The EU Child Cohort Network creates great opportunities for researchers to use data from different cohorts, during and beyond the LifeCycle Project duration. It also provides a novel model for collaborative research in large research infrastructures with individual-level data. The LifeCycle Project will translate results from research using the EU Child Cohort Network into recommendations for targeted prevention strategies to improve health trajectories for current and future generations by optimizing their earliest phases of life.Peer reviewe
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