The security of the BLT signature scheme with practical implementation issues

Abstract—KSI infrastructure is a time-stamping and server-based signature solution deployed in Estonia to provide the integrity and timing information of data. With the goal of providing a personal signature that does not depend on the long-term secrecy of signing keys, Buldas et al. have proposed a BLT scheme that is based on the KSI infrastructure. Although Buldas et al. have shown that the (modified) BLT scheme is secure in the theoretical model, the fact that its practical implementation does not follow that description. In this paper, we will evaluate and provide two attack scenarios if the BLT schema is implemented in such a way, and then propose a solution to that problem. Tóm tắt—Hạ tầng KSI là một giải pháp chữ ký dựa trên máy chủ chứa thông tin thời gian được thử nghiệm triển khai ở Estonia để cung cấp tính toàn vẹn và thông tin về thời gian của dữ liệu.Với mục tiêu tạo ra một chữ ký số cá nhân mà không phụ thuộc vào tính bí mật lâu dài của các khóa ký, Buldas và các cộng sự đã đề xuất lược đồ BLT dựa trên nền của hạ tầng KSI. Mặc dù, Buldas và các cộng sự đã chỉ ra rằng lược đồ BLT (sửa đổi) là an toàn trong mô hình lý thuyết, nhưng triển khai thực tế của lược đồ này không hoàn toàn tuân theo mô tả đó. Trong bài báo này, chúng tôi sẽ đánh giá và đưa ra hai kịch bản tấn công nếu lược đồ BLT được triển khai như vậy, và sau đó đề xuất một giải pháp cho vấn đề đó.

Sleep and circadian indices for planning post-pandemic university timetables

The aims of the present study were to obtain sleep quality and sleep timing information in a group of university students, and to evaluate the effects of a circadian hygiene education initiative. All students of the University of Padova (approximately 64,000) were contacted by e-mail (major campaigns in October 2019 and October 2020) and directed to an ad hoc website for collection of demographics and sleep quality/timing information. Participants (n=5740) received one of two sets of circadian hygiene advice ('A regular life' or 'Bright days and dark nights'). Every month, they were then asked how easy it had been to comply, and provided with the advice again. At any even month from joining, they completed the sleep quality/timing questionnaires again. Information on academic performance was obtained post hoc, together with representative samples of lecture (n=5972) and exam (n=1800) timings, plus lecture attendances (n=25,302). 52% of students had poor sleep quality and 82% showed signs of sleep deprivation. Those who joined in October 2020, after several months of lockdown and distance learning, had better sleep quality, less sleep deprivation and later sleep habits. The 'Bright days and dark nights' advice resulted in earlier get-up time/midsleep compared to the 'A regular life' advice. Significant changes in most sleep quality and sleep timing variables were observed in both advice groups over time, also in relation to pandemic-related events characterising 2020. Early-chronotype students had better academic performances compared to their later chronotype counterparts. In a multivariate model, sleep quality, chronotype and study subject were independent predictors of academic performance. Taken together, these results underlie the importance of designing circadian-friendly university timetables.

Expanding the gestural model of lexical tone: evidence from two dialects of Serbian

Featural and gestural models of tone differ on the degree to which they include timing information in the representation. However, both assume some kind of simultaneity between tones and their tone-bearing units, where featural models emphasize the role of acoustic relationships and gestural models instead emphasize articulatory coordination. We present the results of two acoustic production studies on two dialects of Serbian, a lexical pitch accent language. In the Belgrade dialect, pitch accents are aligned relatively late in the tone-bearing unit, while in the Valjevo dialect, pitch accents are phonetically retracted, sometimes into the preceding syllable. We varied the syllable onsets of tone-bearing units in falling (experiment 1) and rising (experiment 2) pitch accents, and measured the effects on F0 contours. Despite these differences in phonetic alignment, the phonological system is the same in both dialects. We argue that this apparent mismatch between the phonology and phonetics can be expressed straightforwardly in the Articulatory Phonology framework by allowing tone gestures to coordinate with other gestures in all the ways that segmental gestures can, rather than restricting tone to c-center coordination.

Extensive Air Shower Reconstruction using the timing information from the RF-system of the Astroneu array

The Astroneu cosmic ray telescope is a distributed hybrid array consisting of both scintillator counters and RF antenna detectors used for the detection of extensive air showers (EAS). The array is deployed at the Hellenic Open University campus, on the outskirts of the urban area of Patras in Greece. In the present development phase, the Astroneu telescope includes two stations consisting of 3 scintillation detectors modules (SDM) and one RF antenna while a third station includes 3 particle detectors and 4 RF antennas (3SDM-4RF). In each station, the RF-detectors are operating receiving a common trigger upon a 3-fold coincidence between the particle detectors of the station. In this study we present recent results from the 3SDM-4RF autonomous station related to the estimation of the direction of the incoming cosmic air shower using only the timing information from the 4 RF detectors. The directions of the reconstructed showers using the RF timing are in agreement with the corresponding results using the SDMs timing as well as with the simulation predictions. This verifies that the RF signal emitted from EAS originating form Ultra High Energy Cosmic Rays (UHECR), can be detected even in areas with strong electromagnetic background.

Keystroke Dynamics-Based Authentication System Using Empirical Thresholding Algorithm

In a password-based authentication technique, whenever the typed password and username matches the system database, the secure login page allows the client to access it. Despite the password matching, the proposed method checks the similarity between the typing rhythm of entered password and the rhythm of password samples in client's database. In this paper, a novel algorithmic procedure is presented to authenticate the legal client based on empirical threshold values obtained from the timing information of the client's keystroke dynamics. The exploratory outcomes demonstrate an impressive diminish in both false rejection rate and false acceptance rate. Equal error rate and authentication accuracy are also assessed to show the superiority and robustness of the method. Therefore, the proposed keystroke dynamics-based authentication method can be valuable in securing the system protection as a correlative or substitute form of client validation and as a useful resource for identifying the illegal invasion.

Imprinting on time-structured acoustic stimuli in ducklings

Filial imprinting is a dedicated learning process that lacks explicit reinforcement. The phenomenon itself is narrowly heritably canalized, but its content, the representation of the parental object, reflects the circumstances of the newborn. Imprinting has recently been shown to be even more subtle and complex than previously envisaged, since ducklings and chicks are now known to select and represent for later generalization abstract conceptual properties of the objects they perceive as neonates, including movement pattern, heterogeneity and inter-component relationships of same or different. Here, we investigate day-old Mallard ( Anas platyrhynchos ) ducklings’ bias towards imprinting on acoustic stimuli made from mallards’ vocalizations as opposed to white noise, whether they imprint on the temporal structure of brief acoustic stimuli of either kind, and whether they generalize timing information across the two sounds. Our data are consistent with a strong innate preference for natural sounds, but do not reliably establish sensitivity to temporal relations. This fits with the view that imprinting includes the establishment of representations of both primary percepts and selective abstract properties of their early perceptual input, meshing together genetically transmitted prior pre-dispositions with active selection and processing of the perceptual input.

Staged formation of the supergiant Olympic Dam uranium deposit, Australia

The origins of many supergiant ore deposits remain unresolved because the factors responsible for such extreme metal enrichments are not understood. One factor of critical importance is the timing of mineralization. However, timing information is commonly confounded by the difficulty of dating ore minerals. The world’s largest uranium resource at Olympic Dam, South Australia, is exceptional because the high abundance of U allows U-Pb dating of ore minerals. The Olympic Dam U(-Cu-Au-Ag) ore deposit is hosted in ca. 1.59 Ga rocks, and the consensus has been that the supergiant deposit formed at the same time. We argue that, in fact, two stages of mineralization were involved. Paired in situ U-Pb and trace element analyses of texturally distinct uraninite populations show that the supergiant size and highest-U-grade zones are the result of U addition at 0.7–0.5 Ga, at least one billion years after initial formation. This conclusion is supported by a remarkable clustering of thousands of radiogenic 207Pb/206Pb model ages of Cu sulfide grains at this time. Upgrading of the original ca. 1.59 Ga U deposit to its present size at 0.7–0.5 Ga may have resulted from perturbation of regional fluid flow triggered by global climatic (deglaciation) and tectonic (breakup of Rodinia) events.

Low-Process–Voltage–Temperature-Sensitivity Multi-Stage Timing Monitor for System-on-Chip Applications

High performance and complex system-on-chip (SoC) design require a throughput and stable timing monitor to reduce the impacts of uncertain timing and implement the dynamic voltage and frequency scaling (DVFS) scheme for overall power reduction. This paper presents a multi-stage timing monitor, combining three timing-monitoring stages to achieve a high timing-monitoring resolution and a wide timing-monitoring range simultaneously. Additionally, because the proposed timing monitor has high immunity to the process–voltage–temperature (PVT) variation, it provides a more stable time-monitoring results. The time-monitoring resolution and range of the proposed timing monitor are 47 ps and 2.2 µs, respectively, and the maximum measurement error is 0.06%. Therefore, the proposed multi-stage timing monitor provides not only the timing information of the specified signals to maintain the functionality and performance of the SoC, but also makes the operation of the DVFS scheme more efficient and accurate in SoC design.