Intrusion Tolerant Multi-cloud Storage

Data generation and its utilization in important decision applications has been growing an extremely fast pace, which has made data a valuable resource that needs to be rigorously protected from attackers. Cloud storage systems claim to offer the promise of secure and elastic data storage services that can adapt to changing storage requirements. Despite diligent efforts being made to protect data, recent successful attacks highlight the need for going beyond the existing approaches centered on intrusion prevention, detection and recovery mechanisms. However, most security mechanisms have finite rate of failure, and with intrusion becoming more sophisticated and stealthy, the failure rate appears to be rising. In this paper we propose the use data fragmentation, followed by coding that introduces redundant fragments and dispersing fragments to multiple and independent cloud storage systems with each cloud handling only a single fragments. The paper proposes a multi-cloud fragmented cloud storage system architecture and design of the related software code. Probabilistic analysis is carried to quantify its intrusion tolerance abilities.

I. Introduction

Data is a valuable and critical resource for the normal functioning of all sectors of our society, requiring data to be available from everywhere and at any time without it being exposed or corrupted. Use of data in critical decision making in many domains (e.g., personalized marketing, health care and public health, security & law enforcement, scientific research, autonomous systems, etc.) is rising at a very fast pace; being valuable has also made data an attractive target for cyber attackers. The scope of such attacks is to compromise data security, which is defined in terms of preserving Availability, Confidentiality and Integrity (ACI) of data and of the underlying systems that store, process and transport data. However, the scope of this paper is limited to dealing with attacks while data is in storage. For data storage requirements, cloud based storage services have become the technology-of-choice due to their ability meet the Availability requirements and cost effectiveness. This has led to the emergence of many cloud storage services that can be accessed from anywhere by user applications over the Internet. The popularity of public and private cloud based storage services has been increasing at an exponential rate as evidenced by wide spread usage of services, e.g., Amazon Web Services, Google Drive, DropBox, iCloud, etc. Reliability and high availability mechanisms, incorporated into the cloud storage hardware and software transparently provide their users with highly reliable and available storage services. Despite these advantages of cloud storage services, users have valid concerns regarding privacy and integrity of data uploaded to cloud based storage servers [1]. A recent Verizon report pointedly suggests that 50 percent of all data breaches are caused by entities inside an organization [2].