PRShare: A Framework for Privacy-Preserving, Interorganizational Data Sharing

We consider the task of interorganizational data sharing, in which data owners, data clients, and data subjects have different and sometimes competing privacy concerns. One real-world scenario in which this problem arises is law-enforcement use of phone-call metadata: The data owner is a phone company, the data clients are law-enforcement agencies, and the data subjects are individuals who make phone calls. A key challenge in this type of scenario is that each organization uses its own set of proprietary intraorganizational attributes to describe the shared data; such attributes cannot be shared with other organizations. Moreover, data-access policies are determined by multiple parties and may be specified using attributes that are not directly comparable with the ones used by the owner to specify the data. We propose a system architecture and a suite of protocols that facilitate dynamic, efficient, and privacy-preserving interorganizational data sharing, while allowing each party to use its own set of proprietary attributes. We introduce the novel technique of Attribute-Based Encryption With Oblivious Attribute Translation (OTABE), which plays a crucial role in our solution and may be of independent interest.