Abstract Vehicular ad hoc networks (VANETs) is considered a milestone in improving the safety and efficiency in transportation. Nevertheless, when information from the vehicular communications is combined with data from the cloud, it also introduces some privacy risks by making it easier to track the physical location of vehicles. For this reason, to guarantee the proper performance of a \\{VANET\\} it is essential to protect the service against malicious users aiming at disrupting the proper operation of the network. Current researches usually define a traditional identity-based authentication for nodes, which are loaded with individual credentials. However, the use of these credentials in VANETs without any security mechanism enables vehicle tracking and therefore, violate users’ privacy, a risk that may be overcome by means of appropriate anonymity schemes. This comes at the cost, however, of on the one hand preventing VANET centralized authorities from identifying malicious users and revoking them from the network, or on the other hand to avoid complete anonymity of nodes in front of the CA thus to allow their revocation. In this paper, a novel revocation scheme that is able to track and revoke specific malicious users only after a number of complaints have been received while otherwise guaranteeing node’s k-anonymity is described. The proper performance of these mechanisms has been widely evaluated with NS-2 simulator and an analytical model validated with scripts. The results show that presented work is a promising approach in order to increase privacy protection while allowing revocation with little extra costs.

This paper deals with the use of the Koetter-Vardy soft-decision decoding algorithm to perform identification of guilty users in traitor tracing and fingerprinting schemes. In these schemes, each user is assigned a copy of an object with an embedded codeword. Placing different codewords in different copies makes each copy unique and at the same time allows unique identification of each user. The weakness of these schemes comes in the form of a collusion attack, where a group of dishonest users get together and, by comparing their copies, they create a pirate copy that tries to hide their identities. The concern of the paper is restricted to traitor tracing and fingerprinting schemes based on Reed-Solomon codes. By using the Koetter-Vardy soft-decision decoding algorithm as the core part of the tracing process, three different settings are approached: tracing in traceability codes, tracing in identifiable parent property codes and tracing in binary concatenated fingerprinting codes. It is also discussed how by a careful setting of a reliability matrix all possibly identifiable users can be found.

Abstract Mobile agents are software entities consisting of code, data, and state that can migrate autonomously from host to host executing their code. In such scenario there are some security issues that must be considered. In particular, this paper deals with the protection of mobile agents against manipulation attacks performed by the host, which is one of the main security issues to solve in mobile agent systems. This paper introduces an infrastructure for mobile agent watermarking (MAW). MAW is a lightweight approach that can efficiently detect manipulation attacks performed by potentially malicious hosts that might seek to subvert the normal agent operation. MAW is the first proposal in the literature that adapts software watermarks to verify the execution integrity of an agent. The second contribution of this paper is a technique to punish a malicious host that performed a manipulation attack by using a trusted third party (TTP) called host revocation authority (HoRA). A proof‐of‐concept has also been developed and we present some performance evaluation results that demonstrate the usability of the proposed mechanisms. Copyright © 2010 John Wiley & Sons, Ltd.

The design of cryptographic and security protocols for new scenarios and applications can be computationally expensive. Examples of these can be sensor or mobile ad-hoc networks and electronic voting or auctions applications. In such cases, the aid of an automated tool generating protocols for a predefined problem can be of great utility. This work uses the genetic algorithms (GA) techniques for the automatic design of security networked protocols. When using GA for optimizing protocols the evaluation function is critical. We discuss how can be defined several basic criteria for evaluating security protocols and present some examples for evaluation of different protocols

In a fingerprinting scheme, a distributor places marks in each copy of a digital object. Placing different marks in different copies uniquely identifies the recipient of each copy, and therefore allows tracing of the source of an unauthorised redistribution. A widely used approach to the fingerprinting problem is the use of error correcting codes with a suitable large minimum distance. With this approach, the set of embedded marks in a given copy is precisely a code word of the error correcting code. We present two different approaches that use side information for the tracing process. The first approach deals uses the Guruswami–Sudan errors-and-erasures list decoding algorithm whereas the second approach shows the use of a full side information matrix.

Nowadays, networked electronic devices allow users to access services wherever they are. In an ubiquitous networks, clients notice the network to be everywhere and hence also ask networked services to be accessible everywhere. In such scenario, announcement and discovering of services are crucial. Currently, many service discovery protocols exist, however they are limited to a concrete network technology and most of them do not fit mobility and security requirements for a global and ubiquitous solution. In this paper the authors introduce a multiprotocol service discovery solution for heterogeneous networks and describe their work for including security as a main design goal of the proposal.

This paper considers energy constrained routing protocols and workload balancing techniques for improving MANET routing protocols and energy efficiency. We give new routing protocol that employs adaptive load balancing technique to the MANET routing protocols with node caching enhancement. Also, we show new application of energy efficiency metrics to MANET routing protocols for energy efficiency evaluation of the protocols with limited power supply. Our contributions include: (i) New energy efficient AODV-based node caching routing protocol with adaptive workload balancing (AODV-NC-WLB); (ii) New application of energy efficiency metrics to MANET routing protocols; and (iii) An implementation and simulation study in NS-2 of energy efficient AODV-NC-WLB sustaining considerable improvement in throughput, overhead, delivery ratio and delay over the standard AODV for high work load scenario.

Mobile agents are software entities consisting of code, data and state that can migrate autonomously from host to host performing some actions on behalf of a user. Unfortunately, security issues restrict the use of mobile agents, despite the benefits. The protection of mobile agents against the attacks of malicious hosts is considered the most difficult security problem to solve in mobile agent systems. Previously, the mobile agent watermarking approach (MAW) was presented as a new attack detection technique to aid solving the problem of malicious hosts. That approach was based on embedding a fixed watermark into the mobile agent. Some improvements are now introduced to MAW. Instead of a fixed watermark, the origin host embeds a watermark that can change dynamically during execution. In each host, the marked code creates a data container where the watermark is transferred and the results are hidden. When the agent returns home, the origin host verifies the execution integrity by applying a set of integrity rules to the containers. The paper also explains how MAW can be used to punish malicious hosts by using a trusted third party, the host revocation authority.

Mobile agents are software entities consisting of code and data that can migrate autonomously from host to host executing their code. Despite its benefits, security issues strongly restrict the use of code mobility. The protection of mobile agents against the attacks of malicious hosts is considered the most difficult security problem to solve in mobile agent systems. In O. Esparza et al. [2003] the authors introduced the idea of limiting the execution time in the hosts. Malicious hosts need time to analyze and modify an agent in order to take some profit. Controlling the execution time in the hosts permits detecting manipulation attacks performed by malicious hosts during the agents' execution. This paper presents a protocol for detecting malicious hosts based on the idea of execution time limiting.

Public key cryptography is widely used to provide the security services necessary to develop WEB applications. The PKI is the infrastructure that supports the public key cryptography and the revocation of certificate implies one of its major costs. The authors have developed a revocation system based on the data structures proposed by Naor and Nissim in their authenticated dictionary (AD). Our implementation is called ADMHT and in this paper we address some open issues that are necessary to implement such a system.

Traceability codes are used in copyright protection schemes to prevent illegal redistribution of digital content. A traceability code, C, is a set of codewords with the following identification property: let z be a word that is "generated" by a coalition of codewords U/spl sub/C; then there is at least one codeword in U that is "closer" to z than any other codeword not in U is. If the identification process is to be performed efficiently, then error-correcting codes can be used. We make use of a powerful conceptual tool, called ideal-based code (that includes Reed-Solomon, algebraic-geometric and Chinese reminder theorem codes), introduced by V. Guruswami et al., (see Proc. 41st IEEE Symp. on Foundations of Comp. Science, p.159-68, 2000), to present a general framework for the construction and decoding of traceability codes.

In the multimedia content market, there is the need to protect both intellectual property and distribution rights against dishonest buyers. Traitor tracing schemes provide means to find the guilty party in the case of an illegal redistribution. We consider traitor tracing schemes that use error correcting codes, where each user is assigned a unique set of ordered symbols. Since redistributing the set without modification trivially identifies the guilty user, a group of users, aiming to distort their identities, combine their sets and create a new pirate set. In this case, traitor tracing consists in identifying the users whose set agrees the most with the pirate. We present a traitor tracing algorithm that, taking advantage of soft-decision decoding techniques, finds all possibly identifiable traitors, thus extending the capabilities of previously known tracing algorithms.

In order to provide copyright protection for digital contents, a distributor can place marks in each copy of a digital object. Placing different marks in different copies, makes each copy unique, and at the same time allows one to trace the source of an unauthorized distribution. This embedding mark technique, known as fingerprinting, was introduced by Wagner (1983). A problem arises when a group of dishonest users collude, compare their copies, and by changing the marks where their copies differ they create a new copy that conceals their identities. Codes with the "identifiable parent property" or IPP codes, provide means of traceability in the presence of a collusion attack. We present a new decoding algorithm for IPP codes, that can also be used to improve the performance of the Silverberg-Staddon-Walker (see Advances in Cryptology - ASIACRYPT2001, 2001) IPP algorithms.

In this paper we describe the adopted and implemented solution to provide secure communications over the extended area Ethernet network of the Polytechnic University of Catalonia (U.P.C.). The developed solution is not adapted to the current standards about security on local networks (IEEE-802.10, ISO 7498-2, etc.). This solution is based on the construction of a set of ciphering devices (CRYPTONETS), whose function is similar to the one carried out by a classic bridge, but incorporating ciphering facilities. Moreover, there is a Supervision and Administration Center (SAC), which takes care of the key renewal and System Management. The cryptographic algorithms used are the D.E.S. for the Ethernet frames ciphering, and the R.S.A., for key-management.

The development and the implementation of a security system in a local area network environment are presented. This system is based on an extended Ethernet network, but the methodology used is transferable to different kinds of LCNs and even metropolitan area networks (MANs), with some easy modifications. The adopted solution fulfills all the requirements that must fulfill any security protocol since: it provides cryptographic security services, it is an independent algorithm, it supports transparent operations for protected systems, it does not interfere with the operation of unprotected systems, it provides protocol support of key management independent of data security, and it provides optimal communication with unprotected systems. It also offers advantages such as flexibility, simplicity, low cost, and mobility.

An extended Ethernet LAN is built by connecting several Ethernet segments by means of suitable devices (repeaters, bridges, etc.). A common way to make this interconnection is through a main segment, called the backbone, that joins each of the departments (or, perhaps, building floors) within the owner premises. In this kind of network, data transmission in the backbone is very sensitive to either eavesdropping or manipulation. The implementation of a cryptographic system that protects transmission (providing for both confidentiality and integrity of transmitted data) in this kind of network is addressed. The operation of the proposed system and the specific troubles encountered in implementing it in the local network of the Polytechnic University of Catalonia are presented. An analysis of the functionality of the ciphering bridges is provided and their implementation is studied in detail. Finally, the more relevant results and conclusions are given.>