Keywords: BitTorrent Sync Peer-to-Peer Synchronisation Privacy Digital forensics abstract With professional and home Internet users becoming increasingly concerned with data protection and privacy, the privacy afforded by popular cloud file synchronisation services, such as Dropbox, OneDrive and Google Drive, is coming under scrutiny in the press. A number of these services have recently been reported as sharing information with governmental security agencies without warrants. BitTorrent Sync is seen as an alternative by many and has gathered over two million users by December 2013 (doubling since the previous month). The service is completely decentralised, offers much of the same syn- chronisation functionality of cloud powered services and utilises encryption for data transmission (and optionally for remote storage). The importance of understanding Bit- Torrent Sync and its resulting digital investigative implications for law enforcement and forensic investigators will be paramount to future investigations. This paper outlines the client application, its detected network traffic and identifies artefacts that may be of value as evidence for future digital investigations. a 2014 The Authors. Published by Elsevier Ltd on behalf of DFRWS. This is an open access article under the CC BY-NC-ND license (http: creativecommons.org licenses by-nc-nd 3.0 ).
Many Cloud storage utilities provide a method of synchronisation of files which involves some form of periodic checking to determine if changes have been made to any version being viewed locally or to compare offline copies with their online counterparts as soon as communication can be re-established (network connectivity re-enabled or the application or service restarted). For Dropbox, @cite_0 identified two sets of servers, the control servers owned and operated by Dropbox themselves and the storage management and cloud storage servers hosted by Amazon's EC2 and S3 services. This identification is also verified by @cite_5 .
@cite_0 @cite_5
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Powered by cloud computing, Dropbox not only provides reliable file storage but also enables effective file synchronization and user collaboration. This new generation of service, beyond conventional client server or peer-to-peer file hosting with storage only, has attracted a vast number of Internet users. It is however known that the synchronization delay of Dropbox-like systems is increasing with their expansion, often beyond the accepted level for practical collaboration. In this paper, we present an initial measurement to understand the design and performance bottleneck of the proprietary Dropbox system. Our measurement identifies the cloud servers instances utilized by Dropbox, revealing its hybrid design with both Amazon's S3 (for storage) and Amazon's EC2 (for computation). The mix of bandwidth-intensive tasks (such as content delivery) and computation-intensive tasks (such as compare hash values for the contents) in Dropbox enables seamless collaboration and file synchronization among multiple users; yet their interference, revealed in our experiments, creates a severe bottleneck that prolongs the synchronization delay with virtual machines in the cloud, which has not seen in conventional physical machines. We thus re-model the resource provisioning problem in the Dropbox-like systems and present an interference-aware solution that smartly allocates the Dropbox tasks to different cloud instances. Evaluation results show that our solution remarkably reduces the synchronization delay for this new generation of file hosting service. Keywords: BitTorrent Sync Peer-to-Peer Synchronisation Privacy Digital forensics abstract With professional and home Internet users becoming increasingly concerned with data protection and privacy, the privacy afforded by popular cloud file synchronisation services, such as Dropbox, OneDrive and Google Drive, is coming under scrutiny in the press. A number of these services have recently been reported as sharing information with governmental security agencies without warrants. BitTorrent Sync is seen as an alternative by many and has gathered over two million users by December 2013 (doubling since the previous month). The service is completely decentralised, offers much of the same syn- chronisation functionality of cloud powered services and utilises encryption for data transmission (and optionally for remote storage). The importance of understanding Bit- Torrent Sync and its resulting digital investigative implications for law enforcement and forensic investigators will be paramount to future investigations. This paper outlines the client application, its detected network traffic and identifies artefacts that may be of value as evidence for future digital investigations. a 2014 The Authors. Published by Elsevier Ltd on behalf of DFRWS. This is an open access article under the CC BY-NC-ND license (http: creativecommons.org licenses by-nc-nd 3.0 ). A common problem with disk-based cloud storage services is that performance can vary greatly and become highly unpredictable in a multi-tenant environment. A fundamental reason is the interference between workloads co-located on the same physical disk. We observe that different IO patterns interfere with each other significantly, which makes the performance of different types of workloads unpredictable when they are executed concurrently. Unpredictability implies that users may not get a fair share of the system resources from the cloud services they are using. At the same time, replication is commonly used in cloud storage for high reliability. Connecting these two facts, we propose a cloud storage system designed to minimize workload interference without increasing storage costs or sacrificing the overall system throughput. Our design leverages log-structured disk layout, chain replication and a workload-based replica selection strategy to minimize interference, striking a balance between performance and fairness. Our initial results suggest that this approach is a promising way to improve the performance and predictability of cloud storage. Amazon.com’s Elastic Compute Cloud (EC2), Simple Storage Service (S3) and Simple Queue Service (SQS) offer enterprise-class computing, storage and coordination facilities to any organization or individual in the world with a valid credit card. This paper details our experience working with these commodity grid computing services between November 2006 and May 2007, including an analysis of the overall system’s API and ease-of-use; an analysis of EC2’s management and security facilities; an end-to-end performance analysis of S3’s throughput and latency as observed from Amazon’s EC2 cluster and other locations on the Internet; and an analysis of the SQS operation and performance. We conclude with a report of our experience moving a large-scale research application from dedicated hardware to the Amazon offering. We find that this collection of AmazonWeb Services (AWS) has great promise but are hobbled by service consistency problems, the lack of a Service Level Agreement (SLA), and a problematic Web Services Licensing Agreement (WSLA).