45 research outputs found
On Secure Distributed Data Storage Under Repair Dynamics
We address the problem of securing distributed storage systems against
passive eavesdroppers that can observe a limited number of storage nodes. An
important aspect of these systems is node failures over time, which demand a
repair mechanism aimed at maintaining a targeted high level of system
reliability. If an eavesdropper observes a node that is added to the system to
replace a failed node, it will have access to all the data downloaded during
repair, which can potentially compromise the entire information in the system.
We are interested in determining the secrecy capacity of distributed storage
systems under repair dynamics, i.e., the maximum amount of data that can be
securely stored and made available to a legitimate user without revealing any
information to any eavesdropper. We derive a general upper bound on the secrecy
capacity and show that this bound is tight for the bandwidth-limited regime
which is of importance in scenarios such as peer-to-peer distributed storage
systems. We also provide a simple explicit code construction that achieves the
capacity for this regime.Comment: 5 pages, 4 figures, to appear in Proceedings of IEEE ISIT 201
Network Codes Resilient to Jamming and Eavesdropping
We consider the problem of communicating information over a network secretly
and reliably in the presence of a hidden adversary who can eavesdrop and inject
malicious errors. We provide polynomial-time, rate-optimal distributed network
codes for this scenario, improving on the rates achievable in previous work.
Our main contribution shows that as long as the sum of the adversary's jamming
rate Zo and his eavesdropping rate Zi is less than the network capacity C,
(i.e., Zo+Zi<C), our codes can communicate (with vanishingly small error
probability) a single bit correctly and without leaking any information to the
adversary. We then use this to design codes that allow communication at the
optimal source rate of C-Zo-Zi, while keeping the communicated message secret
from the adversary. Interior nodes are oblivious to the presence of adversaries
and perform random linear network coding; only the source and destination need
to be tweaked. In proving our results we correct an error in prior work by a
subset of the authors in this work.Comment: 6 pages, to appear at IEEE NetCod 201