Securing Data in Storage: A Review of Current Research
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paper_title: A Framework for Evaluating Storage System Security

paper_content:

There are a variety of ways to ensure the security of data and the integrity of data transfer, depending on the set of anticipated attacks, the level of security desired by data owners, and the level of inconvenience users are willing to tolerate. Current storage systems secure data either by encrypting data on the wire, or by encrypting data on the disk. These systems seem very different, and currently there are no common parameters for comparing them. In this paper we propose a framework in which both types of systems can be evaluated along the security and performance axes. In particular, we show that all of the existing systems merely make different trade-offs along a single continuum and among a set of related security primitives. We use a trace from a time-sharing UNIX server used by a medium-sized workgroup to quantify the costs associated with each of these secure storage systems. We show that encrypt-on-disk systems offer both increased security and improved performance over encrypt-on-wire in the traced environment.
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paper_title: Security for Network Attached Storage Devices

paper_content:

Abstract : This paper presents a novel cryptographic capability system addressing the security and performance needs of network attached storage systems in which file management functions occur at a different location than the file storage device. In our NASD system file managers issue capabilities to client machines, which can then directly access files stored on the network attached storage device without intervention by a file server. These capabilities may be reused by the client, so that interaction with the file manager is kept to a minimum. Our system emphasizes performance and scalability while separating the roles of decision maker (issuing capabilities) and verifier (validating a capability). We have demonstrated our system with adaptations of both the NFS and AFS distributed file systems using a prototype NASD implementation.
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paper_title: Intrusion Detection, Diagnosis, and Recovery with Self-Securing Storage

paper_content:

Self-securing storage turns storage devices into active parts of an intrusion survival strategy. From behind a thin storage interface (e.g., SCSI or CIFS), a self-securing storage server can watch storage requests, keep a record of all storage activity, and prevent compromised clients from destroying stored data. This paper describes three ways selfsecuring storage enhances an administrator’s ability to detect, diagnose, and recover from client system intrusions. First, storage-based intrusion detection offers a new observation point for noticing suspect activity. Second, post-hoc intrusion diagnosis starts with a plethora of normally-unavailable information. Finally, post-intrusion recovery is reduced to restarting the system with a pre-intrusion storage image retained by the server. Combined, these features can improve an organization’s ability to survive successful digital intrusions. We thank the members and companies of the PDL Consortium (including EMC, Hewlett-Packard, Hitachi, IBM, Intel, Network Appliance, Panasas, Seagate, Sun, and Veritas) for their interest, insights, feedback, and support. We thank IBM and Intel for hardware grants supporting our research efforts. This material is based on research sponsored by the Air Force Research Laboratory, under agreement number F49620-01-1-0433. The U.S. Government is authorized to reproduce and distribute reprints for Governmental purposes notwithstanding any copyright notation thereon. The views and conclusions contained herein are those of the authors and should not be interpreted as necessarily representing the official policies or endorsements, either expressed or implied, of the Air Force Research Laboratory or the U.S. Government. This work is partially funded by DARPA/ITO’s OASIS program (Air Force contract number F30602-99-2-0539-AFRL). Craig Soules is supported by a USENIX Fellowship. Garth Goodson is supported by an IBM Fellowship.
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paper_title: A cryptographic file system for UNIX

paper_content:

Although cryptographic techniques are playing an increasingly important role in modern computing system security, user-level tools for encrypting file data are cumbersome and suffer from a number of inherent vulnerabilities. The Cryptographic File System (CFS) pushes encryption services into the file system itself. CFS supports secure storage at the system level through a standard Unix file system interface to encrypted files. Users associate a cryptographic key with the directories they wish to protect. Files in these directories (as well as their pathname components) are transparently encrypted and decrypted with the specified key without further user intervention; cleartext is never stored on a disk or sent to a remote file server. CFS can use any available file system for its underlying storage without modification, including remote file servers such as NFS. System management functions, such as file backup, work in a normal manner and without knowledge of the key. This paper describes the design and implementation of CFS under Unix. Encryption techniques for file system-level encryption are described, and general issues of cryptographic system interfaces to support routine secure computing are discussed.
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paper_title: Fast and secure distributed read-only file system

paper_content:

Internet users increasingly rely on publicly available data for everything from software installation to investment decisions. Unfortunately, the vast majority of public content on the Internet comes with no integrity or authenticity guarantees. This paper presents the self-certifying read-only file system, a content distribution system providing secure, scalable access to public, read-only data. The read-only file system makes the security of published content independent from that of the distribution infrastructure. In a secure area (perhaps off-line), a publisher creates a digitally-signed database out of a file system's contents. The publisher then replicates the database on untrusted content-distribution servers, allowing for high availability. The read-only file system protocol furthermore pushes the cryptographic cost of content verification entirely onto clients, allowing servers to scale to a large number of clients. Measurements of an implementation show that an individual server running on a 550 Mhz Pentium III with FreeBSD can support 1,012 connections per second and 300 concurrent clients compiling a large software package.
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paper_title: Separating key management from file system security

paper_content:

No secure network file system has ever grown to span the Internet. Existing systems all lack adequate key management for security at a global scale. Given the diversity of the Internet, any particular mechanism a file system employs to manage keys will fail to support many types of use.We propose separating key management from file system security, letting the world share a single global file system no matter how individuals manage keys. We present SFS, a secure file system that avoids internal key management. While other file systems need key management to map file names to encryption keys, SFS file names effectively contain public keys, making them self-certifying pathnames. Key management in SFS occurs outside of the file system, in whatever procedure users choose to generate file names.Self-certifying pathnames free SFS clients from any notion of administrative realm, making inter-realm file sharing trivial. They let users authenticate servers through a number of different techniques. The file namespace doubles as a key certification namespace, so that people can realize many key management schemes using only standard file utilities. Finally, with self-certifying pathnames, people can bootstrap one key management mechanism using another. These properties make SFS more versatile than any file system with built-in key management.
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paper_title: Design for a Decentralized Security System For Network Attached Storage

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This paper describes an architecture for a secure file system based on networkattached storage that guarantees end-to-end encryption for all user data. We describe the design of this system, focusing on the features that allow it to ensure that data is written and read only by authorized users, even in the face of attacks such as network snooping and physically capturing the storage media. Our work shows that such a system is feasible given the speeds of today’s microprocessors, and we discuss benchmark results using several popular encryption and authentication algorithms that could be used on storage devices in such a system. Based on these calculations, we present the overall performance of the system, showing that it is nearly as fast as the non-encrypted file systems in wide use today.
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paper_title: Strong Security for Network-Attached Storage

paper_content:

We have developed a scheme to secure network-attached storage systems against many types of attacks. Our system uses strong cryptography to hide data from unauthorized users; someone gaining complete access to a disk cannot obtain any useful data from the system, and backups can be done without allowing the super-user access to cleartext. While insider denial-of-service attacks cannot be prevented (an insider can physically destroy the storage devices), our system detects attempts to forge data. The system was developed using a raw disk, and can be integrated into common file systems. ::: ::: All of this security can be achieved with little penalty to performance. Our experiments show that, using a relatively inexpensive commodity CPU attached to a disk, our system can store and retrieve data with virtually no penalty for random disk requests and only a 15-20% performance loss over raw transfer rates for sequential disk requests. With such a minor performance penalty, there is no longer any reason not to include strong encryption and authentication in network file systems.
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paper_title: Strong security for distributed file systems

paper_content:

We have developed a scheme to secure network-attached storage systems against many types of attacks. Our system uses strong cryptography to hide data from unauthorized users; someone gaining complete access to a disk cannot obtain any useful data from the system, and backups can be done without allowing the super-user access to unencrypted data. While denial-of-service attacks cannot be prevented, our system detects forged data. The system was developed using a raw disk, and can be integrated into common file systems. We discuss the design and security tradeoffs such a distributed file system makes. Our design guards against both remote intruders and those who gain physical access to the disk, using just enough security to thwart both types of attacks. This security can be achieved with little penalty to performance. We discuss the security operations that are necessary for each type of operation, and show that there is no longer any reason not to include strong encryption and authentication in network file systems.
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paper_title: Authenticating network-attached storage

paper_content:

We present an architecture for network-authenticated disks that implements distributed file systems without file servers or encryption. Our system provides network clients with direct network access to remote storage.
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paper_title: A Framework for Evaluating Storage System Security

paper_content:

There are a variety of ways to ensure the security of data and the integrity of data transfer, depending on the set of anticipated attacks, the level of security desired by data owners, and the level of inconvenience users are willing to tolerate. Current storage systems secure data either by encrypting data on the wire, or by encrypting data on the disk. These systems seem very different, and currently there are no common parameters for comparing them. In this paper we propose a framework in which both types of systems can be evaluated along the security and performance axes. In particular, we show that all of the existing systems merely make different trade-offs along a single continuum and among a set of related security primitives. We use a trace from a time-sharing UNIX server used by a medium-sized workgroup to quantify the costs associated with each of these secure storage systems. We show that encrypt-on-disk systems offer both increased security and improved performance over encrypt-on-wire in the traced environment.
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paper_title: Plutus: Scalable Secure File Sharing on Untrusted Storage

paper_content:

Plutus is a cryptographic storage system that enables secure file sharing without placing much trust on the file servers. In particular, it makes novel use of cryptographic primitives to protect and share files. Plutus features highly scalable key management while allowing individual users to retain direct control over who gets access to their files. We explain the mechanisms in Plutus to reduce the number of cryptographic keys exchanged between users by using filegroups, distinguish file read and write access, handle user revocation efficiently, and allow an untrusted server to authorize file writes. We have built a prototype of Plutus on OpenAFS. Measurements of this prototype show that Plutus achieves strong security with overhead comparable to systems that encrypt all network traffic.
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paper_title: Plutus: Scalable Secure File Sharing on Untrusted Storage

paper_content:

Plutus is a cryptographic storage system that enables secure file sharing without placing much trust on the file servers. In particular, it makes novel use of cryptographic primitives to protect and share files. Plutus features highly scalable key management while allowing individual users to retain direct control over who gets access to their files. We explain the mechanisms in Plutus to reduce the number of cryptographic keys exchanged between users by using filegroups, distinguish file read and write access, handle user revocation efficiently, and allow an untrusted server to authorize file writes. We have built a prototype of Plutus on OpenAFS. Measurements of this prototype show that Plutus achieves strong security with overhead comparable to systems that encrypt all network traffic.
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paper_title: SiRiUS: Securing Remote Untrusted Storage

paper_content:

This paper presents SiRiUS, a secure file system designed to be layered over insecure network and P2P file systems such as NFS, CIFS, OceanStore, and Yahoo! Briefcase. SiRiUS assumes the network storage is untrusted and provides its own read-write cryptographic access control for file level sharing. Key management and revocation is simple with minimal out-of-band communication. File system freshness guarantees are supported by SiRiUS using hash tree constructions. SiRiUS contains a novel method of performing file random access in a cryptographic file system without the use of a block server. Extensions to SiRiUS include large scale group sharing using the NNL key revocation construction. Our implementation of SiRiUS performs well relative to the underlying file system despite using cryptographic operations.
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Title: Securing Data in Storage: A Review of Current Research

Section 1: INTRODUCTION
Description 1: Introduce the topic of storage security, its importance, the challenges involved, and provide an overview of the paper's structure.

Section 2: CRITERIA FOR EVALUATION
Description 2: Establish and describe a common set of criteria (confidentiality, integrity, availability, and performance) for evaluating storage security systems.

Section 3: SURVEY
Description 3: Provide a detailed survey of various storage security approaches, evaluating each system based on the established criteria. Subsections address different specific storage systems.

Section 4: CLASSIFICATION AND COMPARISON
Description 4: Classify and compare the surveyed systems based on the criteria discussed in Section 2. Highlight advantages, disadvantages, and specific use cases for each system.

Section 5: CONCLUSIONS
Description 5: Conclude the paper by summarizing the key findings, discussing the variation in design approaches, and providing recommendations for selecting appropriate storage security solutions.