Threshold Schemes from Isogeny Assumptions

We initiate the study of threshold schemes based on the Hard Homogeneous Spaces (HHS) framework of Couveignes. Quantum-resistant HHS based on supersingular isogeny graphs have recently become usable thanks to the record class group precomputation performed for the signature scheme CSI-FiSh. Using the HHS equivalent of the technique of Shamir\u27s secret sharing in the exponents, we adapt isogeny based schemes to the threshold setting. In particular we present threshold versions of the CSIDH public key encryption, and the CSI-FiSh signature schemes. The main highlight is a threshold version of CSI-FiSh which runs almost as fast as the original scheme, for message sizes as low as 1880 B, public key sizes as low as 128 B, and thresholds up to 56; other speed-size-threshold compromises are possible

Ichthyofauna of the Itimbiri, Aruwimi, and Lindi/Tshopo rivers (Congo basin): Diversity and distribution patterns

Background. Although the Congo basin is the second largest river basin in the world and it has been considered a biodiversity hotspot for fish, still many parts of this basin remain poorly studied. In this study, we examined the poorly known ichthyofauna of three major north-eastern tributaries of the Congo basin (Itimbiri, Aruwimi and Lindi/Tshopo). A checklist of the ichthyofauna is provided and two synonymies are presented. As such, it contributes to unraveling the poorly known fish diversity in the whole Congo basin. An improved knowledge of the ichthyofauna is a sound baseline for further studies and conservation Materials and methods. Fish specimens from five recent expeditions have been identified, and the older collection material from the study area, housed at the Royal Museum for Central Africa and other institutions has been checked and re-identified when necessary. Results. In total, 320 species were recorded, 232 of which from the Itimbiri, 246 from the Aruwimi, and 187 from the Lindi/Tshopo, with the Mormyridae being the most dominant family in all three basins. Micralestes sardina  Poll, 1938 is relegated to synonymy with Micralestes humilis Boulenger, 1899, and Enteromius trinotatus (Fowler, 1936) is designated as a replacement name for Enteromius tetraspilus (Pfeffer, 1896). Within the Aruwimi, a clear difference in species richness and composition is apparent between the headwaters (Ituri/Epulu) and the lower reaches near the Congo main stream. The headwaters are characterised by low species richness, with the Cyprinidae being the most dominant family, while the lower reaches are more species rich, with mormyrid species being the most dominant. The presence of two waterfalls on the Ituri/Epulu has a noticeable impact on the fish distribution. Finally, the hypothesis that an ancient connection between the north-eastern part of the Congo basin and the region of the Albertine Rift is still reflected in their present ichthyofauna is not confirmed. Conclusion. This study provides a first checklist of the ichthyofauna in the north-eastern tributaries of the Congo basin, and illustrates the influence of physical barriers on fish diversity and distribution

Six new dactylogyrid species (Platyhelminthes, Monogenea) from the gills of cichlids (Teleostei, Cichliformes) from the Lower Congo Basin

The Lower Congo Basin is characterized by a mangrove-lined estuary at its mouth and, further upstream, by many hydrogeographical barriers such as rapids and narrow gorges. Five localities in the mangroves and four from (upstream) left bank tributaries or pools were sampled. On the gills of Coptodon tholloni, Coptodon rendalli, Hemichromis elongatus, Hemichromis stellifer and Tylochromis praecox, 17 species of parasites (Dactylogyridae & Gyrodactylidae, Monogenea) were found, eight of which are new to science. Six of these are herein described: Cichlidogyrus bixlerzavalai n. sp. and Cichlidogyrus omari n. sp. from T praecox, Cichlidogyrus calycinus n. sp. and Cichlidogyrus polyenso n. sp. from H. elongatus, Cichlidogyrus kmentovae n. sp. from H. stellifer and Onchob-della ximenae n. sp. from both species of Hemichromis. On Cichlidogyrus reversati a ridge on the accessory piece was discovered that connects to the basal bulb of the penis. We report a putative spillback effect of the native parasites Cichlidogyrus berradae, Cichlidogyrus cubitus and Cichlidogyrus flexicolpos from C. tholloni to the introduced C. rendalli. From our results, we note that the parasite fauna of Lower Congo has a higher affinity with the fauna of West African and nearby freshwater ecoregions than it has with fauna of other regions of the Congo Basin and Central Africa

Sashimi: Cutting up CSI-FiSh Secret Keys to Produce an Actively Secure Distributed Signing Protocol

timestamp: Wed, 15 Apr 2020 17:44:56 +0200 biburl: https://dblp.org/rec/conf/pqcrypto/CozzoS20.bib bibsource: dblp computer science bibliography, https://dblp.orgstatus: publishe

Congo basin: From carbon to fishes COBAFISH. Final Report

The Congo River harbours the richest known fish species diversity on the African continent. Its fish fauna also represents a major source of proteins for the riparian human population. Despite of this, the ecology, dynamics and ecosystem functioning of the Congo River remain poorly understood. The overall goal of the COBAFISH project is to link terrestrial inputs, primary producers (algae and quatic macrophytes), macro-invertebrate and fish biodiversity to ecosystem dynamics and functioning in the Congo River in order to delineate factors that drive species and trophic biodiversity of fishes.COBAFIS

Alignment of COI sequences of data set A+B

Alignment of 932 DNA sequences of the 5'-end of the cytochrome c oxidase subunit I gene (COI, 652 bp) obtained in this study (741 sequences) and retrieved from public repositories (191 sequences which were collected in the same part of the Congolese drainage system) (data set A+B). Labels indicate the sequence ID, the (morpho)species identification, the voucher unique ID and the molecular operational taxonomic unit (MOTU) identifier obtained using three methods (ABGD, GMYC and bPTP)

Stronger and Faster Side-Channel Protections for CSIDH

This work has been accepted in LATINCRYPT-2019International audienceCSIDH is a recent quantum-resistant primitive based on the difficulty of finding isogeny paths between supersingular curves. Recently, two constant-time versions of CSIDH have been proposed: first by Meyer, Campos and Reith, and then by Onuki, Aikawa, Yamazaki and Takagi. While both offer protection against timing attacks and simple power consumption analysis, they are vulnerable to more powerful attacks such as fault injections. In this work, we identify and repair two oversights in these algorithms that compromised their constant-time character. By exploiting Edwards arithmetic and optimal addition chains, we produce the fastest constant-time version of CSIDH to date. We then consider the stronger attack scenario of fault injection, which is relevant for the security of CSIDH static keys in embedded hardware. We propose and evaluate a dummy-free CSIDH algorithm. While these CSIDH variants are slower, their performance is still within a small constant factor of less-protected variants. Finally, we discuss derandomized CSIDH algorithms

DNA barcoding fishes from the Congo and the Lower Guinean provinces: Assembling a reference library for poorly inventoried fauna

The Congolese and Lower Guinean ichthyological provinces are understudied hotspots of the global fish diversity. Here, we barcoded 741 specimens from the Lower and Middle Congo River and from three major drainage basins of the Lower Guinean ichthyological province, Kouilou-Niari, Nyanga and Ogowe. We identified 194 morphospecies belonging to 82 genera and 25 families. Most morphospecies (92.8%) corresponded to distinct clusters of DNA barcodes. Of the four morphospecies present in both neighbouring ichthyological provinces, only one showed DNA barcode divergence <2.5%. A small fraction of the fishes barcoded here (12.9% of the morphospecies and 16.1% of the barcode clusters representing putative species) were also barcoded in a previous large-scale DNA analysis of freshwater fishes of the Lower Congo published in 2011 (191 specimens, 102 morphospecies). We compared species assignments before and after taxonomic updates and across studies performed by independent research teams and observed that most cases of inconsistent species assignments were due to unknown diversity (undescribed species and unknown intraspecific variation). Our results report more than 17 putative new species and show that DNA barcode data provide a measure of genetic variability that facilitates the inventory of underexplored ichthyofaunae. However, taxonomic scrutiny, associated with revisions and new species descriptions, is indispensable to delimit species and build a coherent reference library.</p