Cloud computing is perceived as the “holy grail” to cope with the handling of tremendous amounts of data collected every day from sensors, social networks, mobile devices, etc. However, many organizations are reluctant to resort to cloud technologies. Indeed, the inherent transfer of control over storage and computation to untrusted cloud servers raises various security challenges. In this regard, verifying cloud operations can help users have more control over their resources and can reduce the impact of mistrust in the cloud. Besides, allowing some operations over the data, such as search functionalities, while ensuring the privacy of the data and the queries, can reduce the doubts of using cloud technologies.

This talk presents new cryptographic protocols that enable cloud users to verify (i) the correct storage of outsourced data and (ii) the correct execution of outsourced computation. I will first describe a cryptographic protocol that generates proofs of retrievability, which enable data owners to verify that the cloud correctly stores their data. I will then present cryptographic schemes for verifiable computation by focusing on three operations frequent in data processing routines, namely polynomial evaluation, matrix multiplication and conjunctive keyword search. I will finally focus on the problem of searchable encryption that allows users to search over encrypted data outsourced at a cloud server.