Auditing to Keep Online Storage Services Honest

A growing number of online service providers offer to store customers’ photos, email, file system backups, and other digital assets. Currently, customers cannot make informed decisions about the risk of losing data stored with any particular service provider, reducing their incentive to rely on these services. We argue that thirdparty auditing is important in creating an online serviceoriented economy, because it allows customers to evaluate risks, and it increases the efficiency of insurancebased risk mitigation. We describe approaches and system hooks that support both internal and external auditing of online storage services, describe motivations for service providers and auditors to adopt these approaches, and list challenges that need to be resolved for such auditing to become a reality.