Jens-Matthias Bohli is Chief Researcher in IT-Security at NEC
Laboratories Europe. Before joining NEC, he obtained a masters and PhD
degree in computer science from the University of Karlsruhe. His
research interests focus around security and privacy in Cloud Computing
and the Internet of Things.
Proofs of Retrievability (POR) are cryptographic proofs that enable a
cloud provider to prove that a user can retrieve his data from the Cloud
in its entirety. However, the burden of executing a POR is placed on the
client, which hinders the large-scale adoption of POR by cloud users.
This talk introduces the notion of outsourced proofs of retrievability
(OPOR), in which users can contract an external auditor to perform and
verify POR with the cloud provider. We look at the security risks of
OPORS that have not been covered by the existing POR security models and
present a concrete instantiation of an OPOR. OPOR can be seen as a
building block on the way to building legislation-aware clouds and to
establishing a cyber-insurance market.