1,720,978 research outputs found
Protecting Resources and Regulating Access in Centralized and Decentralized Cloud Systems
Full text linkThe low costs and high reliability guarantees associated with cloud storage led many organizations to offload their data to the cloud. Yet, this raises new challenges to manage access control and data confidentiality. Cloud service providers can be classified as centralized (managed by a single entity) and decentralized (peer-to-peer solutions). Both these scenarios have security and privacy issues. One example is how to prevent the service provider from accessing the data while being able to easily manage access regulation, such as revoking access privileges from some specific users.
The first part of this doctoral thesis analyzes the centralized scenario. In this setting, the provider complies with users' requests, but it might access unprotected data. A possible defense is to encrypt the data; but, standard encryption modes would introduce relevant overheads when performing access revocation. We present an approach that relies on a resource transformation that provides strong mutual inter-dependency in its encrypted representation. To revoke access to a resource, it is then sufficient to update a small portion of it.
The second part studies how these guarantees can be extended to the decentralized cloud-storage environments, where data is offloaded in a peer-to-peer network, in which nodes might be dishonest and try to disobey users' deletion and access revocation requests to maximize their revenue. We propose a solution that addresses both availability and security guarantees and enables resource owners to tune these settings to their needs.
When dealing with decentralized networks, an important aspect is how to detect misbehaving nodes. To address this problem, in the third part of this thesis, we detail a novel way of deploying self-releasing time-locked secrets. This technique can be used to implement delegated challenge-response protocols that, in turn, can guarantee data confidentiality and retrievability properties in fully decentralized systems
Protecting Resources and Regulating Access in Centralized and Decentralized Cloud Systems
Full text linkEncSwift and key management: An integrated approach in an industrial setting
Full text linkThe use of cloud technology is continually expanding. Yet, in many scenarios the adoption of an external cloud service provider may be a worry for data confidentiality since it leads to a partially loss of control over data. One of the solutions for letting users put trust in a provider is the use of encryption to protect data. EncSwift [1] is a solution that provides transparent support for the encryption of objects stored on OpenStack based providers, adopting Barbican, the OpenStack secret storage, as a key manager. In this work we introduce a new key manager, BT KMS, already adopted in industrial systems, that offers a large set of features, and that it is designed to be flexible, transparent, and scalable. Moreover, we analyze the possibility of integration between the BT KMS and the EncSwift approach, and provide an architectural overview of this new integrated system
Securing Resources in Decentralized Cloud Storage
Full text linkDecentralized cloud storage services represent a promising opportunity for a different cloud market, meeting the supply and demand for IT resources of an extensive community of users. The dynamic and independent nature of the resulting infrastructure introduces security concerns that can represent a slowing factor toward the realization of such an opportunity, otherwise clearly appealing and promising for the expected economic benefits. In this paper, we present an approach enabling resource owners to effectively protect and securely delete their resources while relying on decentralized cloud services for their storage. Our solution combines All-Or-Nothing-Transform for strong resource protection, and carefully designed strategies for slicing resources and for their decentralized allocation in the storage network. We address both availability and security guarantees, jointly considering them in our model and enabling resource owners to control their setting
An SELinux-based intent manager for Android
Full text linkThe support for Mandatory Access Control offered by SELinux has become a significant component of the security design of the Android operating system, offering robust protection and the ability to support system-level policies enforced by all the elements of the system. A well-known security-sensitive aspect of Android that currently SELinux does not cover is the abuse of intents, which represent the Android approach to inter-process communication. We propose SEIntentFirewall, an SELinux intent manager that provides fine-grained access control over Intent objects, permitting to cover within MAC policies the use of intents
Policy Specialization to Support Domain Isolation
Full text linkThe exponential growth of modern information systems has introduced several new challenges in the management of security requirements. Nowadays, the technological scenario has evolved and the introduction of MAC models provides a better isolation among software components and reduces the damages that the malicious or defective ones can cause to the systems. On one hand it is important to confine applications and limit the privileges that they can request. On the other hand we want to let applications benefit from the flexibility given by MAC models, such as SELinux.
In this paper we show how the constructs already available in SELinux and the specialization of security domains can be leveraged to define boundaries where the applications are confined but still able to introduce sophisticated security patterns, such as application isolation and the least privilege principle. After defining the proposed model, we describe how it can be integrated into real systems through the use of examples on Android and Apache Web Server
SeSQLite: Security Enhanced SQLite
Full text linkSQLite is the most widely deployed in-process library that implements a SQL database engine. It offers high storage efficiency, fast query operation and small memory needs. Due to the fact that a complete SQLite database is stored in a single cross-platform disk file and SQLite does not support multiple users, anyone who has direct access to the file can read the whole database content. SELinux was originally developed as a Mandatory Access Control (MAC) mechanism for Linux to demonstrate how to overcome DAC limitations. However, SELinux provides per-file protection, thus the database file is treated as an atomic unit, impeding the definition of a fine-grained mandatory access control (MAC) policy for database objects.
We introduce SeSQLite, an SQLite extension that integrates SELinux access controls into SQLite with minimal performance and storage overhead. SeSQLite implements labeling and access control at both schema level (for tables and columns) and row level. This permits the management of a fine-grained access policy for database objects. A prototype has been implemented and it has been used to improve the security of Android Content Providers
Protecting resources and regulating access in cloud-based object storage
No full textCloud storage services offer a variety of benefits that make them extremely attractive for the management of large amounts of data. These services, however, raise some concerns related to the proper protection of data that, being stored on servers of third party cloud providers, are no more under the data owner control. The research and development community has addressed these concerns by proposing solutions where encryption is adopted not only for protecting data but also for regulating accesses. Depending on the trust assumption on the cloud provider offering the storage service, encryption can be applied at the server side, client side, or through an hybrid approach. The goal of this chapter is to survey these encryption-based solutions and to provide a description of some representative systems that adopt such solutions
I Told You Tomorrow: Practical Time-Locked Secrets using Smart Contracts
Full text linkA Time-Lock enables the release of a secret at a future point in time. Many approaches implement Time-Locks as cryptographic puzzles, binding the recovery of the secret to the solution of the puzzle. Since the time required to find the puzzle's solution may vary due to a multitude of factors, including the computational effort spent, these solutions may not suit all scenarios. To overcome this limitation, we propose I Told You Tomorrow (ITYT), a novel way of implementing time-locked secrets based on smart contracts. ITYT relies on the blockchain to measure the elapse of time, and it combines threshold cryptography with economic incentives and penalties to replace cryptographic puzzles. We implement a prototype of ITYT on top of the Ethereum blockchain. The prototype leverages secure Multi-Party Computation to avoid any single point of trust. We also analyze resiliency to attacks with the help of economic game theory, in the context of rational adversaries. The experiments demonstrate the low cost and limited resource consumption associated with our approach
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