Countering Targeted File Attacks Using Location Keys

Serverless distributed computing has received significant attention from both the industry and research community. One of its typical applications is wide area network file systems like CFS [4], Farsite [2] and OceanStore [9]. A unique feature of these file systems is that they are serverless. They store files on a large collection of untrusted nodes that form an overlay network. They use cryptographic techniques to secure files from malicious nodes. However, most of these distributed file systems are vulnerable to targeted file attacks, wherein an adversary attempts to attack a small (chosen) set of files in the system. This paper presents location keys as a technique for countering targeted file attacks. Location keys can be used to not only provide traditional cryptographic guarantees like file confidentiality and integrity, but also (i) mitigate Denial-ofService (DoS) and host compromise attacks, (ii) construct an efficient file access control mechanism, and (iii) add almost zero performance overhead and very minimal storage overhead to the system. We also study several potential inference attacks on location keys and present solutions that guard the file system from such attacks.