529 research outputs found
Using Sphinx to Improve Onion Routing Circuit Construction
This paper presents compact message formats for onion routing circuit construction using the Sphinx methodology developed for mixes. We significantly compress the circuit construction messages for three onion routing protocols that have emerged as enhancements to the Tor anonymizing network; namely, Tor with predistributed Diffie-Hellman values, pairing-based onion routing, and certificateless onion routing. Our new circuit constructions are also secure in the universal composability framework, a property that was missing from the original constructions. Further, we compare the performance of our schemes with their older counterparts as well as with each other
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
Security and Privacy Issues in Wireless Mesh Networks: A Survey
This book chapter identifies various security threats in wireless mesh
network (WMN). Keeping in mind the critical requirement of security and user
privacy in WMNs, this chapter provides a comprehensive overview of various
possible attacks on different layers of the communication protocol stack for
WMNs and their corresponding defense mechanisms. First, it identifies the
security vulnerabilities in the physical, link, network, transport, application
layers. Furthermore, various possible attacks on the key management protocols,
user authentication and access control protocols, and user privacy preservation
protocols are presented. After enumerating various possible attacks, the
chapter provides a detailed discussion on various existing security mechanisms
and protocols to defend against and wherever possible prevent the possible
attacks. Comparative analyses are also presented on the security schemes with
regards to the cryptographic schemes used, key management strategies deployed,
use of any trusted third party, computation and communication overhead involved
etc. The chapter then presents a brief discussion on various trust management
approaches for WMNs since trust and reputation-based schemes are increasingly
becoming popular for enforcing security in wireless networks. A number of open
problems in security and privacy issues for WMNs are subsequently discussed
before the chapter is finally concluded.Comment: 62 pages, 12 figures, 6 tables. This chapter is an extension of the
author's previous submission in arXiv submission: arXiv:1102.1226. There are
some text overlaps with the previous submissio
Dingledine and buddies 2004; how to read computer science papers and stop worrying about the future.
One of many more ways in which computer science can be conducted.
We guide the reader through Dingledine et al.’s 2004 paper on Tor
A Survey on Anonymous On-Demand Routing Protocols for MANETs
At present Mobile ad hoc networks (MANET) is used in many real time applications and hence such networks are vulnerable to different kinds of security threats. MANET networks suffered more from security attacks due to use of free wireless communication frequency spectrum and dynamic topology. Therefore it becomes very tough to provide security to MANET under different adversarial environments like battlefields. For MANET, anonymous communications are vital under the adversarial environments, in which the identification of nodes as well as routes is replaced by pseudonyms or random numbers for the purpose of protection. There are many protocols presented for anonymous communication security for MANET, which hide node identities and routes from exterior observers in order to provide anonymity protection. This paper presents review of various anonymous on demand routing protocols
Secure and privacy-aware proxy mobile IPv6 protocol for vehicle-to-grid networks
Vehicle-to-Grid (V2G) networks have emerged as a new communication paradigm between Electric Vehicles (EVs) and the Smart Grid (SG). In order to ensure seamless communications between mobile EVs and the electric vehicle supply equipment, the support of ubiquitous and transparent mobile IP communications is essential in V2G networks. However, enabling mobile IP communications raises real concerns about the possibility of tracking the locations of connected EVs through their mobile IP addresses. In this paper, we employ certificate-less public key cryptography in synergy with the restrictive partially blind signature technique to construct a secure and privacy-aware proxy mobile IPv6 (SP-PMIPv6) protocol for V2G networks. SP-PMIPv6 achieves low authentication latency while protecting the identity and location privacy of the mobile EV. We evaluate the SP-PMIPv6 protocol in terms of its authentication overhead and the information-theoretic uncertainty derived by the mutual information metric to show the high level of achieved anonymity
Practical privacy enhancing technologies for mobile systems
Mobile computers and handheld devices can be used today to connect to services available on the Internet. One of the predominant technologies in this respect for wireless Internet connection is the IEEE 802.11 family of WLAN standards. In many countries, WLAN access can be considered ubiquitous; there is a hotspot available almost anywhere. Unfortunately, the convenience provided by wireless Internet access has many privacy tradeoffs that are not obvious to mobile computer users. In this thesis, we investigate the lack of privacy of mobile computer users, and propose practical enhancements to increase the privacy of these users.
We show how explicit information related to the users' identity leaks on all layers of the protocol stack. Even before an IP address is configured, the mobile computer may have already leaked their affiliation and other details to the local network as the WLAN interface openly broadcasts the networks that the user has visited. Free services that require authentication or provide personalization, such as online social networks, instant messengers, or web stores, all leak the user's identity. All this information, and much more, is available to a local passive observer using a mobile computer.
In addition to a systematic analysis of privacy leaks, we have proposed four complementary privacy protection mechanisms. The main design guidelines for the mechanisms have been deployability and the introduction of minimal changes to user experience. More specifically, we mitigate privacy problems introduced by the standard WLAN access point discovery by designing a privacy-preserving access-point discovery protocol, show how a mobility management protocol can be used to protect privacy, and how leaks on all layers of the stack can be reduced by network location awareness and protocol stack virtualization. These practical technologies can be used in designing a privacy-preserving mobile system or can be retrofitted to current systems
Distributed Key Generation and Its Applications
Numerous cryptographic applications require a trusted authority to hold a secret. With a plethora of malicious attacks over the Internet, however, it is difficult to establish and maintain such an authority in online systems. Secret-sharing schemes attempt to solve this problem by distributing the required trust to hold and use the secret over multiple servers; however, they still require a trusted {\em dealer} to choose and share the secret, and have problems related to single points of failure and key escrow. A distributed key generation (DKG) scheme overcomes these
hurdles by removing the requirement of a dealer in secret sharing. A (threshold) DKG scheme achieves this using a complete distribution of the trust among a number of servers such that any subset of servers of size greater than a given threshold can reveal or use the shared secret, while
any smaller subset cannot. In this thesis, we make contributions to DKG in the computational security setting and describe three applications of it.
We first define a constant-size commitment scheme for univariate polynomials over finite fields and use it to reduce the size of broadcasts required for DKG protocols in the synchronous communication model by a linear factor. Further, we observe that the existing (synchronous) DKG protocols do not provide a liveness guarantee over the Internet and design the first DKG protocol for use over the Internet. Observing the necessity of long-term stability, we then present proactive security and group modification protocols for our DKG system. We also demonstrate the practicality of our DKG protocol over the Internet by testing our implementation over PlanetLab.
For the applications, we use our DKG protocol to define IND-ID-CCA secure distributed private-key generators (PKGs) for three important identity-based encryption (IBE) schemes: Boneh and Franklin's BF-IBE, Sakai and Kasahara's SK-IBE, and Boneh and Boyen's BB1-IBE.
These IBE schemes cover all three important IBE frameworks: full-domain-hash IBEs, exponent-inversion IBEs and commutative-blinding IBEs respectively, and our distributed PKG constructions can easily be
modified for other IBE schemes in these frameworks. As the second application, we use our distributed PKG for BF-IBE to define an onion routing circuit construction mechanism in the identity-based setting,
which solves the scalability problem in single-pass onion routing circuit construction without hampering forward secrecy. As the final application, we use our DKG implementation to design a threshold signature architecture for quorum-based distributed hash tables and use it to define two robust communication protocols in these peer-to-peer systems
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