Low-voltage distribution grids experience a rising penetration of inverter-based, distributed generation. In order to not only contribute to but also solve voltage problems, these inverters are increasingly asked to participate in intelligent grid controls. Communicating inverters implement distributed voltage droop controls. The impact of cyber-attacks to the stability of such distributed grid controls is poorly researched and therefore addressed in this article. We characterize the potential impact of several attack scenarios by employing the positivity and diagonal dominance properties. In particular, we discuss measurement falsification scenarios where the attacker corrupts voltage measurement data received by the voltage droop controllers. Analytical, control-theoretic methods for assessing the impact on system stability and voltage magnitude are presented and validated via simulation. ... Read more

In cloud computing, the paradigm of data outsourcing introduces security challenges, which requires an independent auditing service to check the data integrity in the cloud. Many existing integrity checking protocols cannot be applied to the auditing service because they can only deal with static data, but it is natural for the client to dynamically update their remotely stored data. Thus, an efficient and secure auditing protocol enabling data dynamics is desired to convince the client that the data are correctly stored in the cloud. In this work, we propose a privacy-preserving public auditing cloud storage protocol enabling data dynamics in the standard model. Inspired by a recent homomorphic network coding signature scheme, we employ a data integrity auditing protocol based on the strong RSA assumption, and extend it to enable a third party auditor to audit client's data without learning the data content. Then we further extend our auditing protocol to support the data dynamic operations (modification, insertion and deletion), which achieves high security level in the standard model. At last we prove the security and justify the performance of our proposed protocol through concrete experiments and comparisons with the state of the art. ... Read more