1,724 research outputs found
Cloud Data Auditing Using Proofs of Retrievability
Cloud servers offer data outsourcing facility to their clients. A client
outsources her data without having any copy at her end. Therefore, she needs a
guarantee that her data are not modified by the server which may be malicious.
Data auditing is performed on the outsourced data to resolve this issue.
Moreover, the client may want all her data to be stored untampered. In this
chapter, we describe proofs of retrievability (POR) that convince the client
about the integrity of all her data.Comment: A version has been published as a book chapter in Guide to Security
Assurance for Cloud Computing (Springer International Publishing Switzerland
2015
The Secure Link Prediction Problem
Link Prediction is an important and well-studied problem for social networks.
Given a snapshot of a graph, the link prediction problem predicts which new
interactions between members are most likely to occur in the near future. As
networks grow in size, data owners are forced to store the data in remote cloud
servers which reveals sensitive information about the network. The graphs are
therefore stored in encrypted form.
We study the link prediction problem on encrypted graphs. To the best of our
knowledge, this secure link prediction problem has not been studied before. We
use the number of common neighbors for prediction. We present three algorithms
for the secure link prediction problem. We design prototypes of the schemes and
formally prove their security. We execute our algorithms in real-life datasets.Comment: This has been accepted for publication in Advances in Mathematics of
Communications (AMC) journa
Analyzing Cascading Failures in Smart Grids under Random and Targeted Attacks
We model smart grids as complex interdependent networks, and study targeted
attacks on smart grids for the first time. A smart grid consists of two
networks: the power network and the communication network, interconnected by
edges. Occurrence of failures (attacks) in one network triggers failures in the
other network, and propagates in cascades across the networks. Such cascading
failures can result in disintegration of either (or both) of the networks.
Earlier works considered only random failures. In practical situations, an
attacker is more likely to compromise nodes selectively.
We study cascading failures in smart grids, where an attacker selectively
compromises the nodes with probabilities proportional to their degrees; high
degree nodes are compromised with higher probability. We mathematically analyze
the sizes of the giant components of the networks under targeted attacks, and
compare the results with the corresponding sizes under random attacks. We show
that networks disintegrate faster for targeted attacks compared to random
attacks. A targeted attack on a small fraction of high degree nodes
disintegrates one or both of the networks, whereas both the networks contain
giant components for random attack on the same fraction of nodes.Comment: Accepted for publication in 28th IEEE International Conference on
Advanced Information Networking and Applications (AINA) 201
Tropical Fukaya Algebras
We introduce a tropical version of the Fukaya algebra of a Lagrangian
submanifold and use it to show that tropical Lagrangian tori are weakly
unobstructed. Tropical graphs arise as large-scale behavior of
pseudoholomorphic disks under a multiple cut operation on a symplectic manifold
that produces a collection of cut spaces each containing relative normal
crossing divisors, following works of Ionel and Brett Parker. Given a
Lagrangian submanifold in the complement of the relative divisors in one of the
cut spaces, the structure maps of the broken Fukaya algebra count broken disks
associated to rigid tropical graphs. We introduce a further degeneration of the
matching conditions (similar in spirit to Bourgeois' version of symplectic
field theory) which results in a tropical Fukaya algebra whose structure maps
are sums of products over vertices of tropical graphs. We show the tropical
Fukaya algebra is homotopy equivalent to the original Fukaya algebra. In the
case of toric Lagrangians contained in a toric component of the degeneration,
an invariance argument implies the existence of projective Maurer-Cartan
solutions.Comment: 167 pages, 17 figures. We fixed some issues with framings of broken
maps pointed out to us by Mohammad F. Tehrani, whom we than
CryptoMaze: Atomic Off-Chain Payments in Payment Channel Network
Payment protocols developed to realize off-chain transactions in Payment
channel network (PCN) assumes the underlying routing algorithm transfers the
payment via a single path. However, a path may not have sufficient capacity to
route a transaction. It is inevitable to split the payment across multiple
paths. If we run independent instances of the protocol on each path, the
execution may fail in some of the paths, leading to partial transfer of funds.
A payer has to reattempt the entire process for the residual amount. We propose
a secure and privacy-preserving payment protocol, CryptoMaze. Instead of
independent paths, the funds are transferred from sender to receiver across
several payment channels responsible for routing, in a breadth-first fashion.
Payments are resolved faster at reduced setup cost, compared to existing
state-of-the-art. Correlation among the partial payments is captured,
guaranteeing atomicity. Further, two party ECDSA signature is used for
establishing scriptless locks among parties involved in the payment. It reduces
space overhead by leveraging on core Bitcoin scripts. We provide a formal model
in the Universal Composability framework and state the privacy goals achieved
by CryptoMaze. We compare the performance of our protocol with the existing
single path based payment protocol, Multi-hop HTLC, applied iteratively on one
path at a time on several instances. It is observed that CryptoMaze requires
less communication overhead and low execution time, demonstrating efficiency
and scalability.Comment: 30 pages, 9 figures, 1 tabl
- …