152 research outputs found
The Mason Test: A Defense Against Sybil Attacks in Wireless Networks Without Trusted Authorities
Wireless networks are vulnerable to Sybil attacks, in which a malicious node
poses as many identities in order to gain disproportionate influence. Many
defenses based on spatial variability of wireless channels exist, but depend
either on detailed, multi-tap channel estimation - something not exposed on
commodity 802.11 devices - or valid RSSI observations from multiple trusted
sources, e.g., corporate access points - something not directly available in ad
hoc and delay-tolerant networks with potentially malicious neighbors. We extend
these techniques to be practical for wireless ad hoc networks of commodity
802.11 devices. Specifically, we propose two efficient methods for separating
the valid RSSI observations of behaving nodes from those falsified by malicious
participants. Further, we note that prior signalprint methods are easily
defeated by mobile attackers and develop an appropriate challenge-response
defense. Finally, we present the Mason test, the first implementation of these
techniques for ad hoc and delay-tolerant networks of commodity 802.11 devices.
We illustrate its performance in several real-world scenarios
Foundations, Properties, and Security Applications of Puzzles: A Survey
Cryptographic algorithms have been used not only to create robust ciphertexts
but also to generate cryptograms that, contrary to the classic goal of
cryptography, are meant to be broken. These cryptograms, generally called
puzzles, require the use of a certain amount of resources to be solved, hence
introducing a cost that is often regarded as a time delay---though it could
involve other metrics as well, such as bandwidth. These powerful features have
made puzzles the core of many security protocols, acquiring increasing
importance in the IT security landscape. The concept of a puzzle has
subsequently been extended to other types of schemes that do not use
cryptographic functions, such as CAPTCHAs, which are used to discriminate
humans from machines. Overall, puzzles have experienced a renewed interest with
the advent of Bitcoin, which uses a CPU-intensive puzzle as proof of work. In
this paper, we provide a comprehensive study of the most important puzzle
construction schemes available in the literature, categorizing them according
to several attributes, such as resource type, verification type, and
applications. We have redefined the term puzzle by collecting and integrating
the scattered notions used in different works, to cover all the existing
applications. Moreover, we provide an overview of the possible applications,
identifying key requirements and different design approaches. Finally, we
highlight the features and limitations of each approach, providing a useful
guide for the future development of new puzzle schemes.Comment: This article has been accepted for publication in ACM Computing
Survey
Security in peer-to-peer communication systems
P2PSIP (Peer-to-Peer Session Initiation Protocol) is a protocol developed by the IETF (Internet Engineering Task Force) for the establishment, completion and modi¿cation of communication sessions that emerges as a complement to SIP (Session Initiation Protocol) in environments where the original SIP protocol may fail for technical, ¿nancial, security, or social reasons. In order to do so, P2PSIP systems replace all the architecture of servers of the original SIP systems used for the registration and location of users, by a structured P2P network that distributes these functions among all the user agents that are part of the system. This new architecture, as with any emerging system, presents a completely new security problematic which analysis, subject of this thesis, is of crucial importance for its secure development and future standardization.
Starting with a study of the state of the art in network security and continuing with more speci¿c systems such as SIP and P2P, we identify the most important security services within the architecture of a P2PSIP communication system: access control, bootstrap, routing, storage and communication. Once the security services have been identi¿ed, we conduct an analysis of the attacks that can a¿ect each of them, as well as a study of the existing countermeasures that can be used to prevent or mitigate these attacks. Based on the presented attacks and the weaknesses found in the existing measures to prevent them, we design speci¿c solutions to improve the security of P2PSIP communication systems. To this end, we focus on the service that stands as the cornerstone of P2PSIP communication systems¿ security: access control. Among the new designed solutions stand out: a certi¿cation model based on the segregation of the identity of users and nodes, a model for secure access control for on-the-¿y P2PSIP systems
and an authorization framework for P2PSIP systems built on the recently published Internet Attribute Certi¿cate Pro¿le for Authorization.
Finally, based on the existing measures and the new solutions designed, we de¿ne a set of security recommendations that should be considered for the design, implementation and maintenance of P2PSIP communication systems.Postprint (published version
Routing Security Issues in Wireless Sensor Networks: Attacks and Defenses
Wireless Sensor Networks (WSNs) are rapidly emerging as an important new area
in wireless and mobile computing research. Applications of WSNs are numerous
and growing, and range from indoor deployment scenarios in the home and office
to outdoor deployment scenarios in adversary's territory in a tactical
battleground (Akyildiz et al., 2002). For military environment, dispersal of
WSNs into an adversary's territory enables the detection and tracking of enemy
soldiers and vehicles. For home/office environments, indoor sensor networks
offer the ability to monitor the health of the elderly and to detect intruders
via a wireless home security system. In each of these scenarios, lives and
livelihoods may depend on the timeliness and correctness of the sensor data
obtained from dispersed sensor nodes. As a result, such WSNs must be secured to
prevent an intruder from obstructing the delivery of correct sensor data and
from forging sensor data. To address the latter problem, end-to-end data
integrity checksums and post-processing of senor data can be used to identify
forged sensor data (Estrin et al., 1999; Hu et al., 2003a; Ye et al., 2004).
The focus of this chapter is on routing security in WSNs. Most of the currently
existing routing protocols for WSNs make an optimization on the limited
capabilities of the nodes and the application-specific nature of the network,
but do not any the security aspects of the protocols. Although these protocols
have not been designed with security as a goal, it is extremely important to
analyze their security properties. When the defender has the liabilities of
insecure wireless communication, limited node capabilities, and possible
insider threats, and the adversaries can use powerful laptops with high energy
and long range communication to attack the network, designing a secure routing
protocol for WSNs is obviously a non-trivial task.Comment: 32 pages, 5 figures, 4 tables 4. arXiv admin note: substantial text
overlap with arXiv:1011.152
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