Distributed Social Network - data security

The present day Internet provides a wide range of services users can benefit from. Some of the services require gathering, processing and presenting data that come from many users in order to deliver additional information. The suitable example can be social networking service. The more valuable data it stores and processes, the more profitable it can become. Users’ personal data can constitute significant value. One of the issues of social networking is storing and processing data by only one entity. Users cannot choose the most suitable security policy because there is only one provided for certain social network. Being part of it, means accepting the risk of unauthorized data distribution and data leakage because of application vulnerabilities. This paper presents new architecture of social network, which provides mechanisms for dividing data between more than one entity and combining independent data repositories in order to deliver one social network with clearly defined interfaces used to connect new data sources

Vector Approach to Context Data Reliability

Context-aware processing is a part of intensively developed ubiquitous computing andmobile systems. Surrounding awareness is used to introduce new functions and solutions. Somecategories of the context data are taken for security purposes in the context-aware security implementations.This kind of data has to meet some conditions since it is used for decision making aboutsecurity mechanisms adaptation and configuration. One of these conditions is reliability. The paperpresents vector approach to context data reliability assessment introducing mechanism which allowsto assess reliability parameters for further usage in context aware security processing. The followingaspects of the context data are taken into account: interface reliability, data quality, data source reliabilityand security level. Introducing reliability metric for context data may be beneficial to othermechanisms which utilize context data. The vector form of reliability may be even more flexible thanthe scalar value

Context data acquisition using adaptive non-repudiation model

The subject of this study is the non-repudiation security service for network communication using TCP/IP stack. Generated evidence, as well as decision-making process of registering a given event, are context-aware. Non-repudiation is equipped with context-awareness by using widely utilized network tools. The aim of this paper is to present timing results for selected tools execution and to complete the evidence generation time. In some applications it is crucial to gather evidence data as fast as possible because of the rapidly changing network environment. For such situations, in case of prolonged execution time, an output from a tool might imprecisely describe the contextual situation from the time of the occurrence of an event

Adaptable Context Management Framework for Secure Network Services

Last decades the contextual approach became an important methodology of analysing information processes in the dynamic environment. In this paper we propose a context management framework suitable for secure network services. The framework allows tracking the contextual information from its origin, through all stages of its processing up to application in security services protecting the secure network application. Besides the framework's description, an example of its application in constructing secure voice call network service is given

Population Genomics of Stone Age Eurasia

Summary The transitions from foraging to farming and later to pastoralism in Stone Age Eurasia (c. 11-3 thousand years before present, BP) represent some of the most dramatic lifestyle changes in human evolution. We sequenced 317 genomes of primarily Mesolithic and Neolithic individuals from across Eurasia combined with radiocarbon dates, stable isotope data, and pollen records. Genome imputation and co-analysis with previously published shotgun sequencing data resulted in >1600 complete ancient genome sequences offering fine-grained resolution into the Stone Age populations. We observe that: 1) Hunter-gatherer groups were more genetically diverse than previously known, and deeply divergent between western and eastern Eurasia. 2) We identify hitherto genetically undescribed hunter-gatherers from the Middle Don region that contributed ancestry to the later Yamnaya steppe pastoralists; 3) The genetic impact of the Neolithic transition was highly distinct, east and west of a boundary zone extending from the Black Sea to the Baltic. Large-scale shifts in genetic ancestry occurred to the west of this “Great Divide”, including an almost complete replacement of hunter-gatherers in Denmark, while no substantial ancestry shifts took place during the same period to the east. This difference is also reflected in genetic relatedness within the populations, decreasing substantially in the west but not in the east where it remained high until c. 4,000 BP; 4) The second major genetic transformation around 5,000 BP happened at a much faster pace with Steppe-related ancestry reaching most parts of Europe within 1,000-years. Local Neolithic farmers admixed with incoming pastoralists in eastern, western, and southern Europe whereas Scandinavia experienced another near-complete population replacement. Similar dramatic turnover-patterns are evident in western Siberia; 5) Extensive regional differences in the ancestry components involved in these early events remain visible to this day, even within countries. Neolithic farmer ancestry is highest in southern and eastern England while Steppe-related ancestry is highest in the Celtic populations of Scotland, Wales, and Cornwall (this research has been conducted using the UK Biobank resource); 6) Shifts in diet, lifestyle and environment introduced new selection pressures involving at least 21 genomic regions. Most such variants were not universally selected across populations but were only advantageous in particular ancestral backgrounds. Contrary to previous claims, we find that selection on the FADS regions, associated with fatty acid metabolism, began before the Neolithisation of Europe. Similarly, the lactase persistence allele started increasing in frequency before the expansion of Steppe-related groups into Europe and has continued to increase up to the present. Along the genetic cline separating Mesolithic hunter-gatherers from Neolithic farmers, we find significant correlations with trait associations related to skin disorders, diet and lifestyle and mental health status, suggesting marked phenotypic differences between these groups with very different lifestyles. This work provides new insights into major transformations in recent human evolution, elucidating the complex interplay between selection and admixture that shaped patterns of genetic variation in modern populations

Population genomics of post-glacial western Eurasia

AbstractWestern Eurasia witnessed several large-scale human migrations during the Holocene1–5. Here, to investigate the cross-continental effects of these migrations, we shotgun-sequenced 317 genomes—mainly from the Mesolithic and Neolithic periods—from across northern and western Eurasia. These were imputed alongside published data to obtain diploid genotypes from more than 1,600 ancient humans. Our analyses revealed a ‘great divide’ genomic boundary extending from the Black Sea to the Baltic. Mesolithic hunter-gatherers were highly genetically differentiated east and west of this zone, and the effect of the neolithization was equally disparate. Large-scale ancestry shifts occurred in the west as farming was introduced, including near-total replacement of hunter-gatherers in many areas, whereas no substantial ancestry shifts happened east of the zone during the same period. Similarly, relatedness decreased in the west from the Neolithic transition onwards, whereas, east of the Urals, relatedness remained high until around 4,000 bp, consistent with the persistence of localized groups of hunter-gatherers. The boundary dissolved when Yamnaya-related ancestry spread across western Eurasia around 5,000 bp, resulting in a second major turnover that reached most parts of Europe within a 1,000-year span. The genetic origin and fate of the Yamnaya have remained elusive, but we show that hunter-gatherers from the Middle Don region contributed ancestry to them. Yamnaya groups later admixed with individuals associated with the Globular Amphora culture before expanding into Europe. Similar turnovers occurred in western Siberia, where we report new genomic data from a ‘Neolithic steppe’ cline spanning the Siberian forest steppe to Lake Baikal. These prehistoric migrations had profound and lasting effects on the genetic diversity of Eurasian populations.</jats:p