A Tale of Three Signatures: practical attack of ECDSA with wNAF

One way of attacking ECDSA with wNAF implementation for the scalar multiplication is to perform a side-channel analysis to collect information, then use a lattice based method to recover the secret key. In this paper, we reinvestigate the construction of the lattice used in one of these methods, the Extended Hidden Number Problem (EHNP). We find the secret key with only 3 signatures, thus reaching the theoretical bound given by Fan, Wang and Cheng, whereas best previous methods required at least 4 signatures in practice. Our attack is more efficient than previous attacks, in particular compared to times reported by Fan et al. at CCS 2016 and for most cases, has better probability of success. To obtain such results, we perform a detailed analysis of the parameters used in the attack and introduce a preprocessing method which reduces by a factor up to 7 the overall time to recover the secret key for some parameters. We perform an error resilience analysis which has never been done before in the setup of EHNP. Our construction is still able to find the secret key with a small amount of erroneous traces, up to 2% of false digits, and 4% with a specific type of error. We also investigate Coppersmith\u27s methods as a potential alternative to EHNP and explain why, to the best of our knowledge, EHNP goes beyond the limitations of Coppersmith\u27s methods

Lattice Enumeration for Tower NFS: a 521-bit Discrete Logarithm Computation

International audienceThe Tower variant of the Number Field Sieve (TNFS) is known to be asymptotically the most efficient algorithm to solve the discrete logarithm problem in finite fields of medium characteristics, when the extension degree is composite. A major obstacle to an efficient implementation of TNFS is the collection of algebraic relations, as it happens in dimension greater than 2. This requires the construction of new sieving algorithms which remain efficient as the dimension grows. In this article, we overcome this difficulty by considering a lattice enumeration algorithm which we adapt to this specific context. We also consider a new sieving area, a high-dimensional sphere, whereas previous sieving algorithms for the classical NFS considered an orthotope. Our new sieving technique leads to a much smaller running time, despite the larger dimension of the search space, and even when considering a larger target, as demonstrated by a record computation we performed in a 521-bit finite field GF(p^6). The target finite field is of the same form than finite fields used in recent zero-knowledge proofs in some blockchains. This is the first reported implementation of TNFS

The antisaccade task as an index of sustained goal activation in working memory: modulation by nicotine

The antisaccade task provides a laboratory analogue of situations in which execution of the correct behavioural response requires the suppression of a more prepotent or habitual response. Errors (failures to inhibit a reflexive prosaccade towards a sudden onset target) are significantly increased in patients with damage to the dorsolateral prefrontal cortex and patients with schizophrenia. Recent models of antisaccade performance suggest that errors are more likely to occur when the intention to initiate an antisaccade is insufficiently activated within working memory. Nicotine has been shown to enhance specific working memory processes in healthy adults. MATERIALS AND METHODS: We explored the effect of nicotine on antisaccade performance in a large sample (N = 44) of young adult smokers. Minimally abstinent participants attended two test sessions and were asked to smoke one of their own cigarettes between baseline and retest during one session only. RESULTS AND CONCLUSION: Nicotine reduced antisaccade errors and correct antisaccade latencies if delivered before optimum performance levels are achieved, suggesting that nicotine supports the activation of intentions in working memory during task performance. The implications of this research for current theoretical accounts of antisaccade performance, and for interpreting the increased rate of antisaccade errors found in some psychiatric patient groups are discussed

The involvement of the fronto-parietal brain network in oculomotor sequence learning using fMRI.

The basis of motor learning involves decomposing complete actions into a series of predictive individual components that form the whole. The present fMRI study investigated the areas of the human brain important for oculomotor short-term learning, by using a novel sequence learning paradigm that is equivalent in visual and temporal properties for both saccades and pursuit, enabling more direct comparisons between the oculomotor subsystems. In contrast with previous studies that have implemented a series of discrete ramps to observe predictive behaviour as evidence for learning, we presented a continuous sequence of interlinked components that better represents sequences of actions. We implemented both a classic univariate fMRI analysis, followed by a further multivariate pattern analysis (MVPA) within a priori regions of interest, to investigate oculomotor sequence learning in the brain and to determine whether these mechanisms overlap in pursuit and saccades as part of a higher order learning network. This study has uniquely identified an equivalent frontal-parietal network (dorsolateral prefrontal cortex, frontal eye fields and posterior parietal cortex) in both saccades and pursuit sequence learning. In addition, this is the first study to investigate oculomotor sequence learning during fMRI brain imaging, and makes significant contributions to understanding the role of the dorsal networks in motor learning

An essential role for decorin in bladder cancer invasiveness

Muscle-invasive forms of urothelial carcinomas are responsible for most mortality in bladder cancer. Finding new treatments for invasive bladder tumours requires adequate animal models to decipher the mechanisms of progression, in particular the way tumours interact with their microenvironment. Herein, using the murine bladder tumour cell line MB49 and its more aggressive variant MB49-I, we demonstrate that the adaptive immune system efficiently limits progression of MB49, whereas MB49-I has lost tumour antigens and is insensitive to adaptive immune responses. Furthermore, we unravel a parallel mechanism developed by MB49-I to subvert its environment: de novo secretion of the proteoglycan decorin. We show that decorin overexpression in the MB49/MB49-I model is required for efficient progression, by promoting angiogenesis and tumour cell invasiveness. Finally, we show that these results are relevant to muscle-invasive human bladder carcinomas, which overexpress decorin together with angiogenesis- and adhesion/migration-related genes, and that decorin overexpression in the human bladder carcinoma cell line TCCSUP is required for efficient invasiveness in vitro. We thus propose decorin as a new therapeutic target for these aggressive tumours.Fil: El Behi, Mohamed. Institute Curie; Francia. Centre de Recherche de I; Francia. Inserm; FranciaFil: Krumeich, Sophie. Institute Curie; Francia. Inserm; FranciaFil: Lodillinsky, Catalina. Institute Curie; Francia. Universidad de Buenos Aires. Facultad de Medicina. Instituto de Oncología "Ángel H. Roffo"; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Kamoun, Aurélie. Institute Curie; FranciaFil: Tibaldi, Lorenzo. Institute Curie; Francia. Inserm; FranciaFil: Sugano, Gaël. Institute Curie; Francia. Inserm; FranciaFil: de Reynies, Aurélien. Ligue Nationale Contre le Cancer; FranciaFil: Chapeaublanc, Elodie. Institute Curie; Francia. Centre National de la Recherche Scientifique; FranciaFil: Laplanche, Agnès. Centre National de la Recherche Scientifique; Francia. Institut de Cancérologie Gustave Roussy; FranciaFil: Lebret, Thierry. Hôpital Foch. Service d; Francia. Université de Versailles; FranciaFil: Allory, Yves. Inserm; FranciaFil: Radvanyi, François. Institute Curie; Francia. Centre National de la Recherche Scientifique; FranciaFil: Lantz, Olivier. Institute Curie; Francia. Inserm; FranciaFil: Eijan, Ana Maria. Universidad de Buenos Aires. Facultad de Medicina. Instituto de Oncología "Ángel H. Roffo"; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Bernard Pierrot, Isabelle. Institute Curie; Francia. Centre National de la Recherche Scientifique; FranciaFil: Théery, Clotilde. Institute Curie; Francia. Inserm; Franci

Essential role of GEXP15, a specific Protein Phosphatase type 1 partner, in Plasmodium berghei in asexual erythrocytic proliferation and transmission.

The essential and distinct functions of Protein Phosphatase type 1 (PP1) catalytic subunit in eukaryotes are exclusively achieved through its interaction with a myriad of regulatory partners. In this work, we report the molecular and functional characterization of Gametocyte EXported Protein 15 (GEXP15), a Plasmodium specific protein, as a regulator of PP1. In vitro interaction studies demonstrated that GEXP15 physically interacts with PP1 through the RVxF binding motif in P. berghei. Functional assays showed that GEXP15 was able to increase PP1 activity and the mutation of the RVxF motif completely abolished this regulation. Immunoprecipitation assays of tagged GEXP15 or PP1 in P. berghei followed by immunoblot or mass spectrometry analyses confirmed their interaction and showed that they are present both in schizont and gametocyte stages in shared protein complexes involved in the spliceosome and proteasome pathways and known to play essential role in parasite development. Phenotypic analysis of viable GEXP15 deficient P. berghei blood parasites showed that they were unable to develop lethal infection in BALB/c mice or to establish experimental cerebral malaria in C57BL/6 mice. Further, although deficient parasites produced gametocytes they did not produce any oocysts/sporozoites indicating a high fitness cost in the mosquito. Global proteomic and phosphoproteomic analyses of GEXP15 deficient schizonts revealed a profound defect with a significant decrease in the abundance and an impact on phosphorylation status of proteins involved in regulation of gene expression or invasion. Moreover, depletion of GEXP15 seemed to impact mainly the abundance of some specific proteins of female gametocytes. Our study provides the first insight into the contribution of a PP1 regulator to Plasmodium virulence and suggests that GEXP15 affects both the asexual and sexual life cycle

Sensory Processing of Motor Inaccuracy Depends on Previously Performed Movement and on Subsequent Motor Corrections: A Study of the Saccadic System

When goal-directed movements are inaccurate, two responses are generated by the brain: a fast motor correction toward the target and an adaptive motor recalibration developing progressively across subsequent trials. For the saccadic system, there is a clear dissociation between the fast motor correction (corrective saccade production) and the adaptive motor recalibration (primary saccade modification). Error signals used to trigger corrective saccades and to induce adaptation are based on post-saccadic visual feedback. The goal of this study was to determine if similar or different error signals are involved in saccadic adaptation and in corrective saccade generation. Saccadic accuracy was experimentally altered by systematically displacing the visual target during motor execution. Post-saccadic error signals were studied by manipulating visual information in two ways. First, the duration of the displaced target after primary saccade termination was set at 15, 50, 100 or 800 ms in different adaptation sessions. Second, in some sessions, the displaced target was followed by a visual mask that interfered with visual processing. Because they rely on different mechanisms, the adaptation of reactive saccades and the adaptation of voluntary saccades were both evaluated. We found that saccadic adaptation and corrective saccade production were both affected by the manipulations of post-saccadic visual information, but in different ways. This first finding suggests that different types of error signal processing are involved in the induction of these two motor corrections. Interestingly, voluntary saccades required a longer duration of post-saccadic target presentation to reach the same amount of adaptation as reactive saccades. Finally, the visual mask interfered with the production of corrective saccades only during the voluntary saccades adaptation task. These last observations suggest that post-saccadic perception depends on the previously performed action and that the differences between saccade categories of motor correction and adaptation occur at an early level of visual processing

Plasmodium pseudo-Tyrosine Kinase-like binds PP1 and SERA5 and is exported to host erythrocytes.

Pseudokinases play key roles in many biological processes but they are poorly understood compared to active kinases. Eight putative pseudokinases have been predicted in Plasmodium species. We selected the unique pseudokinase belonging to tyrosine kinase like (TKL) family for detailed structural and functional analysis in P. falciparum and P. berghei. The primary structure of PfpTKL lacks residues critical for kinase activity, supporting its annotation as a pseudokinase. The recombinant pTKL pseudokinase domain was able to bind ATP, but lacked catalytic activity as predicted. The sterile alpha motif (SAM) and RVxF motifs of PfpTKL were found to interact with the P. falciparum proteins serine repeat antigen 5 (SERA5) and protein phosphatase type 1 (PP1) respectively, suggesting that pTKL has a scaffolding role. Furthermore, we found that PP1c activity in a heterologous model was modulated in an RVxF-dependent manner. During the trophozoite stages, PbpTKL was exported to infected erythrocytes where it formed complexes with proteins involved in cytoskeletal organization or host cell maturation and homeostasis. Finally, genetic analysis demonstrated that viable strains obtained by genomic deletion or knocking down PbpTKL did not affect the course of parasite intra-erythrocytic development or gametocyte emergence, indicating functional redundancy during these parasite stages