Biblio

Cloud computing is a rapid growing advanced technology which is Internet based, providing various ways for storage, resource sharing, and various features. It has brought a new way to securely store and share information and data with multiple users and groups. The cloud environment deals with many problems, and one of the most important problems in recent days is the security issues. Sharing the data in a group, in cloud conditions has turned into a blazing theme in up and coming decades. Thus the blasting interest in cloud computing, ways and measures to accomplish secure and effective information and data sharing in the cloud is a flourishing point to be engaged. In this way, the venture centers around empowering information sharing and capacity for a similar gathering inside the cloud with high security and intensity. Therefore, Honey Encryption and Advanced Encryption Standard is used for providing security for the data shared within the group by the crew members in cloud environment. In addition, an access key is provided by the Group Manager to enable access to the documents and files stored in cloud by the users for specific time period.

The usage of cloud for data storage has become ubiquitous. To prevent data leakage and hacks, it is common to encrypt the data (e.g. PDF files) before sending it to a cloud. However, this limits the search for specific files containing certain keywords over an encrypted cloud data. The traditional method is to take down all files from a cloud, store them locally, decrypt and then search over them, defeating the purpose of using a cloud. In this paper, we propose a method, called SecureCSearch, to perform keyword search operations on the encrypted PDF files over cloud in an efficient manner. The proposed method makes use of Shamir's Secret Sharing scheme in a novel way to create encrypted shares of the PDF file and the keyword to search. We show that the proposed method maintains the security of the data and incurs minimal computation cost.

Spreadsheets are widely used in industries for tabular data analysis, visualization and storage. Users often exchange spreadsheets' semi-structured data to collaborative analyze them. Recently, office suites integrated a software module that enables collaborative authoring of office files, including spreadsheets, to facilitate the sharing process. Typically spreadsheets collaborative authoring applications, like Google Sheets or Excel online, need to delocalize the entire file in public cloud storage servers. This choice is not secure for enterprise use because it exposes shared content to the risk of third party access. Moreover, available platforms usually provide coarse grained spreadsheet file sharing, where collaborators have access to all data stored inside a workbook and to all the spreadsheets' formulas used to manipulate those data. This approach limits users' possibilities to disclose only a small portion of tabular data and integrate data coming from different sources (spreadsheets or software platforms). For these reasons enterprise users prefer to control fine grained confidential data exchange and their updates manually through copy, paste, attach-to-email, extract-from-email operations. However unsupervised data sharing and circulation often leads to errors or, at the very least, to inconsistencies, data losses, and proliferation of multiple copies. We propose a model that gives business users a different level of spreadsheet data sharing control, privacy and management. Our approach enables collaborative analytics of tabular data focusing on fine grained spreadsheet data sharing instead of coarse grained file sharing. This solution works with a platform that implements an end to end encrypted protocol for sensitive data sharing that prevents third party access to confidential content. Data are never shared into public clouds but they are transferred encrypted among the administrative domains of collaborators. In this paper we describe the model and the implemented system that enable our solution. We focus on two enterprise use cases we implemented describing how we deployed our platform to speed up and optimize industry processes that involve spreadsheet usage.

With the rising popularity of file-sharing services such as Google Drive and Dropbox in the workflows of individuals and corporations alike, the protection of client-outsourced data from unauthorized access or tampering remains a major security concern. Existing cryptographic solutions to this problem typically require server-side support, involve non-trivial key management on the part of users, and suffer from severe re-encryption penalties upon access revocations. This combination of performance overheads and management burdens makes this class of solutions undesirable in situations where performant, platform-agnostic, dynamic sharing of user content is required. We present NEXUS, a stackable filesystem that leverages trusted hardware to provide confidentiality and integrity for user files stored on untrusted platforms. NEXUS is explicitly designed to balance security, portability, and performance: it supports dynamic sharing of protected volumes on any platform exposing a file access API without requiring server-side support, enables the use of fine-grained access control policies to allow for selective sharing, and avoids the key revocation and file re-encryption overheads associated with other cryptographic approaches to access control. This combination of features is made possible by the use of a client-side Intel SGX enclave that is used to protect and share NEXUS volumes, ensuring that cryptographic keys never leave enclave memory and obviating the need to reencrypt files upon revocation of access rights. We implemented a NEXUS prototype that runs on top of the AFS filesystem and show that it incurs ×2 overhead for a variety of common file and database operations.

As cloud services greatly facilitate file sharing online, there's been a growing awareness of the security challenges brought by outsourcing data to a third party. Traditionally, the centralized management of cloud service provider brings about safety issues because the third party is only semi-trusted by clients. Besides, it causes trouble for sharing online data conveniently. In this paper, the blockchain technology is utilized for decentralized safety administration and provide more user-friendly service. Apart from that, Ciphertext-Policy Attribute Based Encryption is introduced as an effective tool to realize fine-grained data access control of the stored files. Meanwhile, the security analysis proves the confidentiality and integrity of the data stored in the cloud server. Finally, we evaluate the performance of computation overhead of our system.

Cloud Storage Service(CSS) provides unbounded, robust file storage capability and facilitates for pay-per-use and collaborative work to end users. But due to security issues like lack of confidentiality, malicious insiders, it has not gained wide spread acceptance to store sensitive information. Researchers have proposed proxy re-encryption schemes for secure data sharing through cloud. Due to advancement of computing technologies and advent of quantum computing algorithms, security of existing schemes can be compromised within seconds. Hence there is a need for designing security schemes which can be quantum computing resistant. In this paper, a secure file sharing scheme through cloud storage using proxy re-encryption technique has been proposed. The proposed scheme is proven to be chosen ciphertext secure(CCA) under hardness of ring-LWE, Search problem using random oracle model. The proposed scheme outperforms the existing CCA secure schemes in-terms of re-encryption time and decryption time for encrypted files which results in an efficient file sharing scheme through cloud storage.

Among the various challenges faced by the P2P file sharing systems like BitTorrent, the most common attack on the basic foundation of such systems is: Free-riding. Generally, free-riders are the users in the file sharing network who avoid contributing any resources but tend to consume the resources unethically from the P2P network whereas white-washers are more specific category of free-riders that voluntarily leave the system in a frequent fashion and appearing again and again with different identities to escape from the penal actions imposed by the network. BitTorrent being a collaborative distributed platform requires techniques for discouraging and punishing such user behavior. In this paper, we propose that ``Instead of punishing, we may focus more on rewarding the honest peers''. This approach could be presented as an alternative to other mechanisms of rewarding the peers like tit-for-tat [10], reciprocity based etc., built for the BitTorrent platform. The prime objective of BitTrusty is: providing incentives to the cooperative peers by rewarding in terms of cryptocoins based on blockchain. We have anticipated three ways of achieving the above defined objective. We are further investigating on how to integrate these two technologies of distributed systems viz. P2P file sharing systems and blockchain, and with this new paradigm, interesting research areas can be further developed, both in the field of P2P cryptocurrency networks and also when these networks are combined with other distributed scenarios.

In a scenario where user files are stored in a network shared volume, a single computer infected by ransomware could encrypt the whole set of shared files, with a large impact on user productivity. On the other hand, medium and large companies maintain hardware or software probes that monitor the traffic in critical network links, in order to evaluate service performance, detect security breaches, account for network or service usage, etc. In this paper we suggest using the monitoring capabilities in one of these tools in order to keep a trace of the traffic between the users and the file server. Once the ransomware is detected, the lost files can be recovered from the traffic trace. This includes any user modifications posterior to the last snapshot of periodic backups. The paper explains the problems faced by the monitoring tool, which is neither the client nor the server of the file sharing operations. It also describes the data structures in order to process the actions of users that could be simultaneously working on the same file. A proof of concept software implementation was capable of successfully recovering the files encrypted by 18 different ransomware families.

Public cloud data storage services were considered as a potential alternative to store low-cost digital data in the short term. They are offered by different providers on the Internet. Some providers offer limited free plans for the users who are starting the service. However, data security concern arises when data stored are considered as a valuable asset. This study explores the usage of secret sharing scheme: Rabin's IDA and Shamir's SSA to implement a tool called dCloud for file protection stored in public cloud storage in a seamless way. It addresses data security by hiding its complexities when targeting ordinary non-technical users. The secret key is automatically generated by dCloud in a secure random way on Rabin's IDA. Shamir's SSA completes the process through dispersing the key into each of Rabin's IDA output files. Moreover, the Hash value of the original file is added to each of those output files to confirm the integrity of the file during reconstruction. Besides, the authentication key is used to communicate with all of the defined service providers during storage and reconstruction as well. It is stored into local secure key-store. By having a key to access the key-store, an ordinary non-technical user will be able to use dCloud to store and retrieve targeted file within defined public cloud storage services securely.

Cloud storage brokerage systems abstract cloud storage complexities by mediating technical and business relationships between cloud stakeholders, while providing value-added services. This however raises security challenges pertaining to the integration of disparate components with sometimes conflicting security policies and architectural complexities. Assessing the security risks of these challenges is therefore important for Cloud Storage Brokers (CSBs). In this paper, we present a threat modeling schema to analyze and identify threats and risks in cloud brokerage brokerage systems. Our threat modeling schema works by generating attack trees, attack graphs, and data flow diagrams that represent the interconnections between identified security risks. Our proof-of-concept implementation employs the Common Configuration Scoring System (CCSS) to support the threat modeling schema, since current schemes lack sufficient security metrics which are imperatives for comprehensive risk assessments. We demonstrate the efficiency of our proposal by devising CCSS base scores for two attacks commonly launched against cloud storage systems: Cloud sStorage Enumeration Attack and Cloud Storage Exploitation Attack. These metrics are then combined with CVSS based metrics to assign probabilities in an Attack Tree. Thus, we show the possibility combining CVSS and CCSS for comprehensive threat modeling, and also show that our schemas can be used to improve cloud security.

With the continuing evolution of sophisticated APT attacks, provenance tracking is becoming an important technique for efficient attack investigation in enterprise networks. Most of existing provenance techniques are operating on system event auditing that discloses dependence relationships by scrutinizing syscall traces. Unfortunately, such auditing-based provenance is not able to track the causality of another important dimension in provenance, the shared libraries. Different from other data-only system entities like files and sockets, dynamic libraries are linked at runtime and may get executed, which poses new challenges in provenance tracking. For example, library provenance cannot be tracked by syscalls and mapping; whether a library function is called and how it is called within an execution context is invisible at syscall level; linking a library does not promise their execution at runtime. Addressing these challenges is critical to tracking sophisticated attacks leveraging libraries. In this paper, to facilitate fine-grained investigation inside the execution of library binaries, we develop Lprov, a novel provenance tracking system which combines library tracing and syscall tracing. Upon a syscall, Lprov identifies the library calls together with the stack which induces it so that the library execution provenance can be accurately revealed. Our evaluation shows that Lprov can precisely identify attack provenance involving libraries, including malicious library attack and library vulnerability exploitation, while syscall-based provenance tools fail to identify. It only incurs 7.0% (in geometric mean) runtime overhead and consumes 3 times less storage space of a state-of-the-art provenance tool.

Users have accumulated years of personal data in cloud storage, creating potential privacy and security risks. This agglomeration includes files retained or shared with others simply out of momentum, rather than intention. We presented 100 online-survey participants with a stratified sample of 10 files currently stored in their own Dropbox or Google Drive accounts. We asked about the origin of each file, whether the participant remembered that file was stored there, and, when applicable, about that file's sharing status. We also recorded participants' preferences moving forward for keeping, deleting, or encrypting those files, as well as adjusting sharing settings. Participants had forgotten that half of the files they saw were in the cloud. Overall, 83% of participants wanted to delete at least one file they saw, while 13% wanted to unshare at least one file. Our combined results suggest directions for retrospective cloud data management.

We introduce FairSwap – an efficient protocol for fair exchange of digital goods using smart contracts. A fair exchange protocol allows a sender S to sell a digital commodity x for a fixed price p to a receiver R. The protocol is said to be secure if R only pays if he receives the correct x. Our solution guarantees fairness by relying on smart contracts executed over decentralized cryptocurrencies, where the contract takes the role of an external judge that completes the exchange in case of disagreement. While in the past there have been several proposals for building fair exchange protocols over cryptocurrencies, our solution has two distinctive features that makes it particular attractive when users deal with large commodities. These advantages are: (1) minimizing the cost for running the smart contract on the blockchain, and (2) avoiding expensive cryptographic tools such as zero-knowledge proofs. In addition to our new protocols, we provide formal security definitions for smart contract based fair exchange, and prove security of our construction. Finally, we illustrate several applications of our basic protocol and evaluate practicality of our approach via a prototype implementation for fairly selling large files over the cryptocurrency Ethereum. This article is summarized in: the morning paper an interesting/influential/important paper from the world of CS every weekday morning, as selected by Adrian Colyer

Security issues emerging out of the constantly evolving software applications became a huge challenge to software security experts. In this paper, we propose a prototype to detect vulnerabilities by identifying their architectural sources and also use security patterns to mitigate the identified vulnerabilities. We emphasize the need to consider architectural relations to introduce an effective security solution. In this research, we focused on the taint-style vulnerabilities that can induce injection-based attacks like XSS, SQLI in web applications. With numerous tools available to detect the taint-style vulnerabilities in the web applications, we scanned for the presence of repetition of a vulnerable code pattern in the software. Very importantly, we attempted to identify the architectural source files or modules by developing a tool named ArT Analyzer. We conducted a case study on a leading health-care software by applying the proposed architectural taint analysis and identified the vulnerable spots. We could identify the architectural roots for those vulnerable spots with the use of our tool ArT Analyzer. We verified the results by sharing it with the lead software architect of the project. By adopting an architectural solution, we avoided changes to be done on 252 different lines of code by merely introducing 2 lines of code changes at the architectural roots. Eventually, this solution was integrated into the latest updated release of the health-care software.

Cloud-backed file systems provide on-demand, high-availability, scalable storage. Their security may be improved with techniques such as erasure codes and secret sharing to fragment files and encryption keys in several clouds. Attacking the server-side of such systems involves penetrating one or more clouds, which can be extremely difficult. Despite all these benefits, a weak side remains: the client-side. The client devices store user credentials that, if stolen or compromised, may lead to confidentiality, integrity, and availability violations. In this paper we propose RockFS, a cloud-backed file system framework that aims to make the client-side of such systems resilient to attacks. RockFS protects data in the client device and allows undoing unintended file modifications.

Security has always been concern when it comes to data sharing in cloud computing. Cloud computing provides high computation power and memory. Cloud computing is convenient way for data sharing. But users may sometime needs to outsourced the shared data to cloud server though it contains valuable and sensitive information. Thus it is necessary to provide cryptographically enhanced access control for data sharing system. This paper discuss about the promising access control for data sharing in cloud which is identity-based encryption. We introduce the efficient revocation scheme for the system which is revocable-storage identity-based encryption scheme. It provides both forward and backward security of ciphertext. Then we will have glance at the architecture and steps involved in identity-based encryption. Finally we propose system that provide secure file sharing system using identity-based encryption scheme.

Data Deduplication provides lots of benefits to security and privacy issues which can arise as user's sensitive data at risk of within and out of doors attacks. Traditional secret writing that provides knowledge confidentiality is incompatible with knowledge deduplication. Ancient secret writing wants completely different users to encode their knowledge with their own keys. Thus, identical knowledge copies of completely different various users can result in different ciphertexts that makes Deduplication not possible. Convergent secret writing has been planned to enforce knowledge confidentiality whereas creating Deduplication possible. It encrypts/decrypts a knowledge copy with a confluent key, that is obtained by computing the cryptographical hash price of the content of the information copy. Once generation of key and encryption, the user can retain the keys and send ciphertext to cloud.

Internet-based online cloud services provide enormous volumes of storage space, tailor made computing resources and eradicates the obligation of native machines for data maintenance as well. Cloud storage service providers claim to offer the ability of secure and elastic data-storage services that can adapt to various storage necessities. Most of the security tools have a finite rate of failure, and intrusion comes with more complex and sophisticated techniques; the security failure rates are skyrocketing. Once we upload our data into the cloud, we lose control of our data, which certainly brings new security risks toward integrity and confidentiality of our data. In this paper, we discuss a secure file sharing mechanism for the cloud with the disintegration protocol (DIP). The paper also introduces new contribution of seamless file sharing technique among different clouds without sharing an encryption key.

Peer-To-Peer (P2P) networks open up great possibilities for intercommunication, collaborative and social projects like file sharing, communication protocols or social networks while offering advantages over the conventional Client-Server model of computing pattern. Such networks counter the problems of centralized servers such as that P2P networks can scale to millions without additional costs. In previous work, we presented Distributed Data Structure (DDS) which offers a middle-ware scheme for distributed applications. This scheme builds on top of DHT (Distributed Hash Table) based P2P overlays, and offers distributed data storage services as a middle-ware it still needs to address security issues. The main objective of this paper is to investigate possible ways to handle the security problem for DDS, and to develop a possibly reusable security architecture for access control for secure distributed data structures in P2P networks without depending on trusted third parties.

One of the main concerns of Cloud storage solutions is to offer the availability to the end user. Thus, addressing the mobility needs and device's variety has emerged as a major challenge. At first, data should be synchronized automatically and continuously when the user moves from one equipment to another. Secondly, the Cloud service should offer to the owner the possibility to share data with specific users. The paper's goal is to develop a secure framework that ensures file synchronization with high quality and minimal resource consumption. As a first step towards this goal, we propose the SyncDS protocol with its associated architecture. The synchronization protocol efficiency raises through the choice of the used networking protocol as well as the strategy of changes detection between two versions of file systems located in different devices. Our experiment results show that adopting the Hierarchical Hash Tree to detect the changes between two file systems and adopting the WebSocket protocol for the data exchanges improve the efficiency of the synchronization protocol.

There are many risks in moving data into public storage environments, along with an increasing threat around large-scale data leakage. Secret sharing scheme has been proposed as a keyless and resilient mechanism to mitigate this, but scaling through large scale data infrastructure has remained the bane of using secret sharing scheme in big data storage and retrievals. This work applies secret sharing methods as used in cryptography to create robust and secure data storage and retrievals in conjunction with data fragmentation. It outlines two different methods of distributing data equally to storage locations as well as recovering them in such a manner that ensures consistent data availability irrespective of file size and type. Our experiments consist of two different methods - data and key shares. Using our experimental results, we were able to validate previous works on the effects of threshold on file recovery. Results obtained also revealed the varying effects of share writing to and retrieval from storage locations other than computer memory. The implication is that increase in fragment size at varying file and threshold sizes rather than add overheads to file recovery, do so on creation instead, underscoring the importance of choosing a varying fragment size as file size increases.

Cloud computing is becoming more and more popular day by day due to its maintenance, multitenancy and performance. Data owners are motivated to outsource their data to the cloud servers for resource pooling and productivity where multiple users can work on the same data concurrently. These servers offer great convenience and reduced cost for the computation, storage and management of data. But concerns can persist for loss of control over certain sensitive information. The complexity of security is largely intensified when data is distributed over a greater number of devices and data is shared among unrelated users. So these sensitive data should be encrypted for solving these security issues that many consumers cannot afford to tackle. In this paper, we present a dynamic searchable encryption scheme whose update operation can be completed by cloud server while reserving the ability to support multi-keyword ranked search. We have designed a scheme where dynamic operations on data like insert, update and delete are performed by cloud server without decrypting the data. Thus this scheme not only ensures dynamic operations on data but also provides a secure technique by performing those tasks without decryption. The state-of-the-art methods let the data users retrieve the data, re-encrypt it under the new policy and then send it again to the cloud. But our proposed method saves this high computational overhead by reducing the burden of performing dynamic operation by the data owners. The secure and widely used TF × IDF model is used along with kNN algorithm for construction of the index and generation of the query. We have used a tree-based index structure, so our proposed scheme can achieve a sub-linear search time. We have conducted experiments on Amazon EC2 cloud server with three datasets by updating a file, appending a file and deleting a file from the document collection and compared our result with the state-of-the-art method. Results show th- t our scheme has an average running time of 42ms which is 75% less than the existing method.

An effective storage and management of file systems is very much essential now a days to avoid the wastage of storage space provided by the cloud providers. Data de-duplication technique has been used widely which allows only to store a single copy of a file and thus avoids duplication of file in the cloud storage servers. It helps to reduce the amount of storage space and save bandwidth of cloud service and thus in high cost savings for the cloud service subscribers. Today data that we need to store are in encrypted format to ensure the security. So data encryption by data owners with their own keys makes the de-duplication impossible for the cloud service subscriber as the data encryption with a key converts data into an unidentifiable format called cipher text thus encrypting, even the same data, with different keys may result in different cipher texts. But de-duplication and encryption need to work in hand to hand to ensure secure, authorized and optimized storage. In this paper, we propose a scheme for file-level de-duplication on encrypted files like text, images and even on video files stored in cloud based on the user's privilege set and file privilege set. This paper proposed a de-duplication system which distributes the files across different servers. The system uses an Erasure Correcting Code technique to re-construct the files even if the parts of the files are lost by attacking any server. Thus the proposed system can ensure both the security and reliability of encrypted files.

Contemporary cloud environments are built on low-assurance components, so they cannot provide a high level of assurance about the isolation and protection of information. A ``multi-level'' secure cloud environment thus typically consists of multiple, isolated clouds, each of which handles data of only one security level. Not only are such environments duplicative and costly, data ``sharing'' must be implemented by massive, wasteful copying of data from low-level domains to high-level domains. The requirements for certifiable, scalable, multi-level cloud security are threefold: 1) To have trusted, high-assurance components available for use in creating a multi-level secure cloud environment; 2) To design a cloud architecture that efficiently uses the high-assurance components in a scalable way, and 3) To compose the secure components within the scalable architecture while still verifiably maintaining the system security properties. This paper introduces a trusted, high-assurance file server and architecture that satisfies all three requirements. The file server is built on mature technology that was previously certified and deployed across domains from TS/SCI to Unclassified and that supports high-performance, low-to-high and high-to-low file sharing with verifiable security.