CISPA is currently in the founding process to join the German Helmholtz Association as a new member. It is consequently undergoing significant organizational changes, which are not yet reflected on this webpage.

For further information on the above mentioned founding process, please refer to the official press release by the State Chancellery of Saarland.

Recent News on the Transformation Process


The location of the first construction phase has been agreed upon. For further information, please refer to the official press release .

2015-02-17 14:00
Jens-Matthias Bohli NEC Laboratories Europe
MPI-SWS 0.29

Outsourced Proofs of Retrievability

Jens-Matthias Bohli
NEC Laboratories Europe
Title : Outsourced Proofs of Retrievability
Building: E1 5 (MPI-SWS), Room 0.29


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.