Dynamic PDP vs. Dynamic POR: Are they really different ?

As many services are moving to the cloud, we are losing control of our own data. This constitutes one of the biggest problems that we face in this decade. The talk will start simple, presenting basics of cryptographic mechanisms for security protection of outsourced data. The basics will include data structures, such as rank-based authenticated skip lists, used in dynamic provable data possession (DPDP) schemes. Later, we will switch gears, and talk about dynamic proofs of retrievability (DPOR) schemes. At the technical level, the difference is that the POR-type schemes employ erasure codes. We will see how the first DPOR scheme PORAM is achieved with the help of oblivious RAM, and then informally talk about some latest results on how to achieve DPOR without the full complexity of the oblivious RAM constructions. As a surprise, we will talk about how to achieve DPOR using only static PDP and DPDP, meaning that the first DPOR scheme existed (though no one knew) in 2009 already. Finally, we will conclude with a philosophical discussion of their difference in practice.