Pasture: Secure Offline Data Access Using Commodity Trusted Hardware

This paper presents Pasture, a secure messaging and logging library that enables rich mobile experiences by providing secure offline data access. Without trusting users, applications, operating systems, or hypervisors, Pasture leverages commodity trusted hardware to provide two important safety properties: accessundeniability (a user cannot deny any offline data access obtained by his device without failing an audit) and verifiable-revocation (a user who generates a verifiable proof of revocation of unaccessed data can never access that data in the future). For practical viability, Pasture moves costly trusted hardware operations from common data access actions to uncommon recovery and checkpoint actions. We used Pasture to augment three applications with secure offline data access to provide high availability, rich functionality, and improved consistency. Our evaluation suggests that Pasture overheads are acceptable for these applications.