Client Memory Research Articles

Tor forensics: Proposed workflow for client memory artefacts

The Internet is now part of everyday life, and plays a significant role in communication, online shopping, online banking, etc. However, one of the current issues with using the Internet is lack of security since it is still possible for an eavesdropper to be able to intercept transferred data. As a result, the number of incidents has increased, posing a real threat to the user while people have become more conscious about how applications treat their personal data. Therefore, some users have shifted to using The Onion Router (Tor) as it claims to preserve user's anonymity and privacy. However, while using or investigating the use of Tor, the question of how the memory residue of the client leaks anonymity during Tor's interaction arises. This question is addressed in this paper as it investigates how the client's memory residue leaks anonymity before, during, and after Tor's interaction. While there has been significant research on the topic of Tor, there is a gap in the literature concerning Tor forensics. One of the leading concepts to identify artefacts in digital investigation is digital forensics. Thus, this paper will address the question by an experimental method that uses memory forensics tactics on Tor clients to find artefacts related to Tor usage. Subsequently, an analysis of the findings can stand against Tor's claims about the user's privacy and anonymity since the Tor browser keeps a plethora of details about client activities, which could be gained during or even after closing the client session. This paper provides a workflow and a python shell script for analyzing the Tor client's memory residue, which will serve as a workflow and act as a starting point for broadening studies in a similar area. It also introduces a positive impact on the investigators. It aims to make the process easier and contributes to society as users will be aware of how Tor treats their data.

Memory FORESHADOW: Memory FOREnSics of HArDware CryptOcurrency wallets – A Tool and Visualization Framework

We present Memory FORESHADOW: Memory FOREnSics of HArDware cryptOcurrency Wallets. To the best of our knowledge, this is the primary account of cryptocurrency hardware wallet client memory forensics. Our exploratory analysis revealed forensically relevant data in memory including transaction history, extended public keys, passphrases, and unique device identifiers. Data extracted with FORESHADOW can be used to associate a hardware wallet with a computer and allow an observer to deanonymize all past and future transactions due to hierarchical deterministic wallet address derivation. Additionally, our novel visualization framework enabled us to measure both the persistence and integrity of artifacts produced by the Ledger and Trezor hardware wallet clients. The framework can be generalized for use in future memory forensics work.

Client memory and learning of treatment contents: An experimental study of intervention strategies and relationship to outcome in a brief treatment for procrastination

Background and objectivesClient memory and learning is limited for psychological treatment contents. This study investigated different approaches to support client memory and learning of treatment contents and the relationship between memory and learning of treatment contents and outcome. MethodsAdult participants (n = 428) were recruited through Amazon's Mechanical Turk and randomized to complete one of three versions of a one-session procrastination intervention. Two versions of the intervention included different amounts of memory support strategy types from the Memory Support Intervention. A control version did not include any types of memory support. Memory and learning of treatment contents were assessed immediately after the intervention and one week later. Procrastination and two mechanisms of procrastination (impulsiveness and self-efficacy) were assessed at baseline and one week after the intervention. ResultsContrary to the hypotheses, a version of the intervention with multiple types of memory support strategies was not associated with better memory and learning of treatment contents than a version of the intervention with only one type of memory support strategy or the control intervention. Greater memory and learning of treatment contents predicted improvement in mechanisms of procrastination, but not procrastination itself. LimitationsThe mean level of procrastination in this study was lower than in other treatment studies of procrastination. ConclusionsResults partially support the rationale for the Memory Support Intervention that improving client memory and learning of treatment contents can improve outcome. Findings suggest that the Memory Support Intervention may be simplified to include fewer strategies without compromising efficacy.

Therapist perceptions of client memory for psychological treatment contents and use of memory support strategies: A survey study of clinical practice.

Therapist perceptions of client memory for psychological treatment contents and use of memory support strategies: A survey study of clinical practice.

Therapist momentary experiences of disconnection with clients

ABSTRACTTherapist in-session experiences of momentary disconnection from clients have not been previously studied. Four person-centered therapists participated in semi-structured in-depth one-to-one interviews to investigate the nature of these experiences. Using grounded theory analyses and drawing on concepts from emotion-focused therapy and pre-therapy, we identified four types of therapist disconnection process in reaction to difficult client process: becoming overwhelmed by a painful client memory; overidentifying with an embodied client feeling; frustration over the pursuit of a disengaged client; and taking on too much responsibility for a client’s stuckness. They thus involved therapist overinvolvement, which led to emotional dysregulation followed by preoccupying secondary reactive emotions such as grief, panic or guilt at their disconnection. Coping with the trigger by disconnecting and becoming incongruent evoked a conflict between participants’ professional role and their personal needs. By becoming congruent again, therapists were able to reengage with their clients and could reattend to clients’ frames of reference. Participants identified therapist self-insight and self-care as key factors for preventing future disconnection.

Analyzing Data Remnant Remains on User Devices to Determine Probative Artifacts in Cloud Environment.

Cloud storage service allows users to store their data online, so that they can remotely access, maintain, manage, and back up data from anywhere via the Internet. Although helpful, this storage creates a challenge to digital forensic investigators and practitioners in collecting, identifying, acquiring, and preserving evidential data. This study proposes an investigation scheme for analyzing data remnants and determining probative artifacts in a cloud environment. Using pCloud as a case study, this research collected the data remnants available on end-user device storage following the storing, uploading, and accessing of data in the cloud storage. Data remnants are collected from several sources, including client software files, directory listing, prefetch, registry, network PCAP, browser, and memory and link files. Results demonstrate that the collected remnants data are beneficial in determining a sufficient number of artifacts about the investigated cybercrime.

Recursive Trees for Practical ORAM

Abstract We present a new, general data structure that reduces the communication cost of recent tree-based ORAMs. Contrary to ORAM trees with constant height and path lengths, our new construction r-ORAM allows for trees with varying shorter path length. Accessing an element in the ORAM tree results in different communication costs depending on the location of the element. The main idea behind r-ORAM is a recursive ORAM tree structure, where nodes in the tree are roots of other trees. While this approach results in a worst-case access cost (tree height) at most as any recent tree-based ORAM, we show that the average cost saving is around 35% for recent binary tree ORAMs. Besides reducing communication cost, r-ORAM also reduces storage overhead on the server by 4% to 20% depending on the ORAM’s client memory type. To prove r-ORAM’s soundness, we conduct a detailed overflow analysis. r-ORAM’s recursive approach is general in that it can be applied to all recent tree ORAMs, both constant and poly-log client memory ORAMs. Finally, we implement and benchmark r-ORAM in a practical setting to back up our theoretical claims.

Streaming 3D meshes over thin mobile devices

We are witnessing a significant growth in applications using thin mobile devices, such as social networks, virtual walkthrough, massively multiplayer online gaming (MMOG), and augmented reality (AR), just to mention a few. Virtual environments (VE) based class of applications have recently attracted a large number of users. Applications that applied the conventional client-server architecture require the VE to be stored on the client, which is not very feasible due to the client's memory constraints. To address this issue, 3D streaming techniques have been designed and are widely used nowadays. However, several challenges exist and affect the user's Quality of Experience (QoE). By all means, these challenges need to be resolved before the 3D streaming technology over thin mobile devices becomes a commodity. In this paper, we provide a survey on the existing 3D streaming techniques by classifying them based on the nature of the application, and we centralize our attention on methods applied to adapt 3D streaming techniques to the changes in the wireless network conditions. Therefore, we discuss the challenges that the 3D streaming techniques face from a network point of view, as well as the approaches and solutions proposed.

Predictive Modeling of User Interaction Patterns for 3D Mesh Streaming

The complexity in 3D virtual environment over the web is growing rapidly every day. This 3D virtual environment comprises of set of structured static and dynamic scenes and each scene has multiple 3D objects/meshes. Therefore, the granular level in any 3D virtual environments is the object. In 3D virtual environment, it is required to give user interactions for every 3D object and at any point of time, it is enough if the system streams and brings in only the visible portion of the object from server to the client by utilizing the limited network bandwidth and the limited client memory space. This streaming would reduce the time to present the rendered object to the requested clients. Further to reduce the time and effectively utilize the bandwidth and memory space, in proposed work, an attempt is made to exploit the user interactions on 3D object and built a predictive model. The experiment result shows that the built predictive model minimizes the rendering latency of the 3D mesh that is being streamed to the possible extent. Also, the results convey that the reduction in time is subjected to the type of 3D object that is taken for streaming and rendering.

3D Mesh Streaming based on Predictive Modeling

The complexity in 3D virtual environment over the web is growing rapidly every day. This 3D virtual environment comprises a set of structured scenes and each scene has multiple 3D objects/meshes. Therefore the granular level of the block in a virtual environment is the object. In a virtual environment, it is required to give user interactions for every 3D object and at any point of time, it is enough if the system streams and brings in only the visible portion of the object from the server to the client by utilizing the limited network bandwidth and the limited client memory space. This streaming would reduce the time to present the rendered object to the requested clients. Further to reduce the time and effectively utilize the bandwidth and memory space, in the proposed study, an attempt is made to exploit the user interaction on 3D object and built a predictive agent which would minimize the latency in the rendering of the 3D mesh that is being streamed. The experiment result shows that the rendering time and cache miss rates are significantly reduced with the predictive agent.

A Multi-Level Cache Approach for Realtime Visualization of Massive 3D GIS Data

The real-time visualization of 3D GIS at a whole city scale always faces the challenge of dynamic data loading with high-efficiency. Based on the multi-tier distributed 3D GIS framework, this paper presents a multi-level cache approach for dynamic data loading. It aims to establish in 3D GIS spatial database engine (3DGIS-SDE) the unified management mechanism of caches on three levels, including: the client memory cache (CMC) oriented to sharing application, the client file cache (CFC) organized by index, as well as the application server memory cache (ASMC) of structural consistency. With the help of the proposed optimized cache replacement policy, multi-level cache consistency maintenance as well as multithread loading model designed in the paper, the engine is able to adaptively make full use of each-level caches according to their own application properties and achieve effective coordination between them. Finally, a practical 3D GIS database based on Oracle 11g is employed for test. The experimental results prove this approach could satisfy multi-user concurrent applications of 3D visual exploration.

Prioritised Predicted Region based Cache Replacement Policy for location dependent data in mobile environment

Location Dependent Information Services (LDISs) provide information to mobile users depending on their current location. Data has to be transferred from the server to the mobile device, whenever required, due to mobile client's memory constraint. To improve system performance in mobile environment, frequently accessed data must be cached on the mobile client. In this paper, we propose a new cache replacement policy, the Prioritised Predicted Region based Cache Replacement Policy (PPRRP), which uses a cost function for data eviction based on the client's movement pattern. Earlier policies considered only the data distance. Simulation results show significant improvement in system performance with our policy.

Automatic recovering of RTSP sessions in mobile telephones using JADE-LEAP

Streaming is a technique used to transmit information over the network so that its issuing from the server, its communication along the network and its downloading and processing on the client overlapp, and moreover it must not be saved in the client memory. This technique is very effective for transmitting multimedia information (video) and is very suitable for mobile phones because there is no need to store the video in its memory that it is limited (data storage is still quite limited in the last generation mobile phones indeed). While the transmission speed of wireless networks has increased significantly, this technique is still very effective because it hides the latency of the network. On the other hand, the various wireless communication technologies used by mobile phones today (mainly wireless fidelity (WiFi), Bluetooth and 3G) are very likely to suffer physical intermittent disconnections making them miss the video streaming session every time a mobile phone loses network coverage for a certain time and forces him to reconnect manually, with the consequent loss of effectiveness of the streaming technique (that is lost due to the effectiveness of concealment of network latency). This work shows an automatic recovery solution for lost video stream and missed session by creating a new mechanism based on proxies implemented with software agents of the Java platform software development framework-lightweight extensible agent platform (JADE-LEAP). As far as our knowledge, this is the first time the efficient use of this platform for streaming video on mobile phones is tested. In addition, the experimental results obtained are very promising for its effectiveness and relevance to the practical case studies we've tested.

A cache invalidation scheme for continuous partial match queries in mobile computing environments

The continuous partial match query is a partial match query whose result remains consistently in the client's memory. Conventional cache invalidation methods for mobile clients are record ID-based. However, since the partial match query uses content-based retrieval, the conventional ID-based approaches cannot efficiently manage the cache consistency of mobile clients. In this paper, we propose a predicate-based cache invalidation scheme for continuous partial match queries in mobile computing environments. We represent the cache state of a mobile client as a predicate, and also construct a cache invalidation report (CIR), which the server broadcasts to clients for cache management, with predicates. In order to reduce the amount of information that is needed for cache management, we propose a set of methods for CIR construction (in the server) and identification of invalidated data (in the client). Through experiments, we show that the predicate-based approach is very effective for the cache management of mobile clients.

A cost-efficient method for streaming stored content in a guaranteed QoS Internet

Quality-of-service techniques allow network providers to differentiate the services they offer to their customers. This differentiation makes it possible to consider charging new quality transport services based on network resource usage . In a content streaming framework, consumers pay for content and network access. Similarly, content providers pay to reserve transport service resources to deliver high-quality content. Therefore, content providers need new cost-efficient methods that optimize network resource reservations. Our paper proposes a new method that ensures data availability on the client side while optimizing network resource reservation when servers deliver stored content with semi-elastic unicast flows. The method uses network resource reservation to guarantee the delivery rate when stored data is below a minimum threshold in the client memory. When occupancy reaches a maximum threshold, the transmission changes to the classic best-effort service, which is not charged based on usage but at a flat rate. The proper design of these thresholds optimizes transmission cost. We validate our analytical method using the ns-2 simulator. We also present a new approach for improving this method when the best-effort delivery rate from the server to the client presents higher variability. Finally, we analyse the case of several homogeneous clients that simultaneously require resource reservation from the server. To avoid resource reservation rejection in the server, bandwidth must be suitably allocated among the clients. To evaluate this more complex case, we also perform some simulations and implement the associated prototype to validate the simulations. The qualitative simulation results reveal optimum working areas in which usage-cost reduction efficiency of the method is significant and extra signalling is minimum.

Service level agreements in IP networks

Internet services are being deployed over an infrastructure that involves co‐operation between multiple organizations and systems. This has necessitated the need for standard means to share the information between the service providers and their customers. This information essentially pertains to the service level obligations between the service provider and their customers so that the customers can ensure the quality of service (QoS) that they are able to achieve at their end. A service level agreement (SLA) essentially quantifies the level of service as it includes the metrics that define the quality of service. The research undertaken identifies the QoS dimensions, which are required to define the multimedia services. Each application used by the user will involve different values of the QoS dimensions in order to maintain an expected level of service. The QoS requirement for a particular application will also depend upon the provisioning of the network resources depending on the client and server side CPU and memory available for processing. The relationship between the system resources, QoS dimensions and the SLA has been depicted in the form of a general model of SLA and as an example taken for the video conferencing application.

Transactional client-server cache consistency

Client-server database systems based on a data shipping model can exploit client memory resources by caching copies of data items across transaction boundaries. Caching reduces the need to obtain data from servers or other sites on the network. In order to ensure that such caching does not result in the violation of transaction semantics, a transactional cache consistency maintenance algorithm is required. Many such algorithms have been proposed in the literature and, as all provide the same functionality, performance is a primary concern in choosing among them. In this article we present a taxonomy that describes the design space for transactional cache consistency maintenance algorithms and show how proposed algorithms relate to one another. We then investigate the performance of six of these algorithms, and use these results to examine the tradeoffs inherent in the design choices identified in the taxonomy. The results show that the interactions among dimensions of the design space impact performance in many ways, and that classifications of algorithms as simply “pessimistic” or “optimistic” do not accurately characterize the similarities and differences among the many possible cache consistency algorithms.

Survival Patterns of Ontario Long-Term Care Admissions: Seven Years Experience

RÉSUMÉAu cours d'une période de sept ans, allant de 1980 à 1987, une étude a été menée sur le taux de survie des patients placés dans des établissements de soins prolongés de la région d'Hamilton-Wentworth. L'état de tous les patients a été évalué avant que ces derniers ne soient placés par le Service de co-ordination du placement. De plus, leurs dossiers informatisés ont servi à constituer la base de données de l'étude. Au cours des sept années, 25 pour cent des patients sont morts dans des maisons de santé, des maisons pour personnes âgées et des maisons d'hébergement; tandis que 50 pour cent des patients sont morts après avoir été placés dans des centres pour malades chroniques. Environ 10 per cent des décès ont eut lieu au cours de la première année qui a suivi le placement dans des maisons d'hébergement, des maisons pour personnes âgées et des maisons de santé; tandis que 25 pour cent des patients sont morts au cours de la même année dans des centres pour malades chroniques. Le sexe semble jouer un rôle important dans la survivance de l'ensemble des patients. Par contre, l'âge au moment du placement, l'état matrimonial, l'ambulation, les conditions de vie, l'endroit où ils vivaient comparativement à celui où ils se trouvent et le fait que l'endroit où ils devaient être placés et celui où ils sont ne font qu'un, semblent avoir moins d'impact sur le taux de survivance. Il semble y avoir un lien entre le niveau de mémoire des patients au moment où ils furent placés et leur survivance dans des maisons de santé. En effet, les hommes « sans mémoire » et les femmes « sans mémoire » ou affichant un état de « confusion marquée » ont survécu plus longtemps que ceux ayant une mémoire dite « normale «.