Chip-Secured Data Access: Reconciling Access Rights with Data Encryption

The democratization of ubiquitous computing (access data anywhere, anytime, anyhow), the increasing connection of corporate databases to the Internet and the today’s natural resort to Web hosting companies and Database Service Providers strongly emphasize the need for data confidentiality. Users have no other choice than trusting Web companies arguing that their systems are fully secured and their employees are beyond any suspicion [AKS02]. However, database attacks are more and more frequent (their cost is estimated to more than $100 billion per year) and 45% of the attacks are conducted by insiders [FBI02]. Therefore, no one can be fully confident on an invisible DataBase Administrator (DBA) administering confidential data. Traditional database security policies, like user authentication, communication encryption and serverenforced access controls [BPS96] are inoperative against insider attacks. Several attempts have been made to strengthen server-based security approaches thanks to database encryption [Ora02, Mat00, HeW01]. However, as Oracle confesses, server encryption is not the expected “armor plating” because the DBA (or an intruder usurping her identity) has enough privilege to tamper the encryption mechanism and get the clear-text data. Client-based security approaches have been recently investigated. They still rely on database encryption, but encryption and decryption occur only on the client side to prevent any disclosure of clear-text data on the server. Storage Service Providers proposing encrypted backups for personal data [Sky02] are crude representative of the client-based security approach. The management of SQL queries over encrypted data complements well this approach [HIL02]. These solutions provide a convincing way to store and query safely personal data on untrusted servers. However, sharing data among several users is not addressed. Actually, users willing to share data have to share the same encryption keys and then inherit from the same access rights on the data. In a recent paper [BoP02], we precisely addressed this sharing issue. We proposed a solution called C-SDA (Chip-Secured Data Access), which allows querying encrypted data while controlling personal privileges. CSDA is a client-based security component acting as an incorruptible mediator between a client and an encrypted database. This component is embedded into a smartcard to prevent any tampering to occur on the client side. This cooperation of hardware and software security components constitutes a strong guarantee against attacks and allows to reestablish the orthogonality between access right management and data encryption. A full-fledged prototype of C-SDA has been developed with the support of the French ANVAR agency (Agence Nationale pour la VAlorisation de la Recherche). This prototype runs on an advanced JavaCard platform provided by Schlumberger. The objective of the C-SDA prototype demonstration is twofold: • Validate the design of C-SDA by building a real-case application and showing the benefits of the approach.