34,988 research outputs found
Preserving Link Privacy in Social Network Based Systems
A growing body of research leverages social network based trust relationships
to improve the functionality of the system. However, these systems expose
users' trust relationships, which is considered sensitive information in
today's society, to an adversary.
In this work, we make the following contributions. First, we propose an
algorithm that perturbs the structure of a social graph in order to provide
link privacy, at the cost of slight reduction in the utility of the social
graph. Second we define general metrics for characterizing the utility and
privacy of perturbed graphs. Third, we evaluate the utility and privacy of our
proposed algorithm using real world social graphs. Finally, we demonstrate the
applicability of our perturbation algorithm on a broad range of secure systems,
including Sybil defenses and secure routing.Comment: 16 pages, 15 figure
Introducing Accountability to Anonymity Networks
Many anonymous communication (AC) networks rely on routing traffic through
proxy nodes to obfuscate the originator of the traffic. Without an
accountability mechanism, exit proxy nodes risk sanctions by law enforcement if
users commit illegal actions through the AC network. We present BackRef, a
generic mechanism for AC networks that provides practical repudiation for the
proxy nodes by tracing back the selected outbound traffic to the predecessor
node (but not in the forward direction) through a cryptographically verifiable
chain. It also provides an option for full (or partial) traceability back to
the entry node or even to the corresponding user when all intermediate nodes
are cooperating. Moreover, to maintain a good balance between anonymity and
accountability, the protocol incorporates whitelist directories at exit proxy
nodes. BackRef offers improved deployability over the related work, and
introduces a novel concept of pseudonymous signatures that may be of
independent interest.
We exemplify the utility of BackRef by integrating it into the onion routing
(OR) protocol, and examine its deployability by considering several
system-level aspects. We also present the security definitions for the BackRef
system (namely, anonymity, backward traceability, no forward traceability, and
no false accusation) and conduct a formal security analysis of the OR protocol
with BackRef using ProVerif, an automated cryptographic protocol verifier,
establishing the aforementioned security properties against a strong
adversarial model
Symmetric and Synchronous Communication in Peer-to-Peer Networks
Motivated by distributed implementations of game-theoretical algorithms, we
study symmetric process systems and the problem of attaining common knowledge
between processes. We formalize our setting by defining a notion of
peer-to-peer networks(*) and appropriate symmetry concepts in the context of
Communicating Sequential Processes (CSP), due to the common knowledge creating
effects of its synchronous communication primitives. We then prove that CSP
with input and output guards makes common knowledge in symmetric peer-to-peer
networks possible, but not the restricted version which disallows output
statements in guards and is commonly implemented.
(*) Please note that we are not dealing with fashionable incarnations such as
file-sharing networks, but merely use this name for a mathematical notion of a
network consisting of directly connected peers "treated on an equal footing",
i.e. not having a client-server structure or otherwise pre-determined roles.)Comment: polished, modernized references; incorporated referee feedback from
MPC'0
Trust models in ubiquitous computing
We recapture some of the arguments for trust-based technologies in ubiquitous computing, followed by a brief survey of some of the models of trust that have been introduced in this respect. Based on this, we argue for the need of more formal and foundational trust models
- ā¦