SECRYPT 2010 Abstracts

Area 1 - Security in Information Systems and Software Engineering
Full Papers Short Papers
Area 2 - Access Control and Intrusion Detection
Full Papers Short Papers
Area 3 - Network Security and Protocols
Full Papers Short Papers
Area 4 - Cryptographic Techniques and Key Management
Full Papers Short Papers
Area 5 - Information Assurance
Short Papers
Area 6 - Data and Application Security and Privacy
Full Papers Short Papers

Area 1 - Security in Information Systems and Software Engineering

Full Papers
Paper Nr: 57
Title:

Management of Security Policies in Virtual Organisations
Authors:

Benjamin Aziz, Alvaro Arenas, Ian Johnson, Matej Artac, Ales Cernivec and Philip Robinson
Abstract: Grid-based virtual organisations facilitate the sharing of computational resources among users belonging to different organisations and working towards a computationally-intensive goal within some project. The selection, access, usage and release of such resources is usually controlled through the enforcement of security policies that express what is acceptable behaviour by the resources and their users at each stage. This process is complex to manage in large-scale Grid-based systems, therefore, a solution tackling the management of VO policies is desireable. In this paper, we propose one such solution that provides policy management capabilities at each phase of the VO lifecycle. We discuss full aspects of the solution starting from the context and requirements analysis, use cases, design, implementation and finally, qualitative and quantitative evaluation.
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Paper Nr: 134
Title:

Evaluating Survivability and Costs of Three Virtual Machine based Server Architectures
Authors:

Wanyu Zang, Meng Yu, Alex H. Wang, Wanyu Zang and Peng Liu
Abstract: Virtual machine based services are becoming predominant in data centers or cloud computing since virtual machines can provide strong isolation and better monitoring for security purposes. While there are many promising security techniques based on virtual machines, it is not clear how significant the difference between various system architectures can be in term of survivability. In this paper, we analyze the survivability of three virtual machine based architectures --- load balancing architecture, isolated service architecture, and BFT architecture. Both the survivability based on the availability and the survivability under sustained attacks for each architecture are analyzed. Furthermore, the costs of each architecture are compared. The results show that even if the same set of commercial off the shell (COTS) software are used, the performance of various service architectures are largely different in surviving attacks. Our results can be used as guidelines in the service architecture design when survivability to attacks is important.
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Short Papers
Paper Nr: 58
Title:

ACCESS CONTROL MODELS FOR BUSINESS PROCESSES
Authors:

Vahid R. Karimi and Donald D. Cowan
Abstract: A business model describes certain operations of an enterprise, and an important aspect of business operations deals with the specification of access control policies, which are used to constrain the business operations by adding what should, could, or must be. We describe the use of patterns for presenting access control models and policies. Our goal is to specify access control policies such that they are based on access control models and have the capability of policy languages, thereby making the foundational blocks of these policies and operational models identical. Thus, the integration of these policies into operational models is straightforward. To show our approach, we use Role-based Access Control (RBAC), a well-known access control model, and also select a business process model whose foundational building blocks are Resources, Events, and Agents (REA). We make three main contributions: 1) the use of the same foundational building blocks and similar models to describe business processes and access control models, 2) access control policies that are based on an access control model, and 3) access control policies that are rule-based and akin to policy languages. As a result, such models are more understandable, and their future modifications are more straightforward.
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Paper Nr: 60
Title:

ATTACKS ON WEB SERVICES AND MITIGATION SCHEMES
Authors:

Vipul Patel, Radhesh Mohandas and Alwyn Pais
Abstract: Web Services have become dependable platform for e-commerce and many B2B models. Extensive adaptation of Web Services has resulted in a bunch of standards such as WS-Security, WS-Trust etc. to support business and security requirements for the same. Majority of the web services are offered over Http with Simple Object Access Protocol (SOAP) as an underlying exchange infrastructure. This paper describes attacks targeted at Web Services such as XML injection, XSS injection, HTTP header manipulation, sending stale message and other protocol specific attacks. We have used XML Re-Writing mechanism to perform “timestamp modification attack” and WS-Trust, WS-SecureConversation protocols attack. Schemas stated in WSDL file may not be accurate enough to validate messages effectively; Schemas should reflect structure of all possible genuine requests. Hence, we have proposed a new self-adaptive schema hardening algorithm to obtain fine-tuned schema that can be used to validate SOAP messages more effectively. We have also proposed mitigation techniques to counter attacks using MIME/DIME attachments.
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Paper Nr: 64
Title:

Auditing the Defense against Cross Site Scripting in Web Applications
Authors:

Lwin K. Shar and Tan B. Kuan
Abstract: Majority attacks to web applications today are mainly carried out through input manipulation. In such attacks, malicious inputs are submitted by attackers to perform unintended actions of web applications. These are caused by weaknesses of web applications in preventing the manipulation of inputs. Among these attacks, cross site scripting attack -- malicious input is submitted to perform unintended actions on a HTML response page -- is a common type of attacks. This paper proposes an approach for thorough auditing of code to defend against cross site scripting attack. Based on the possible methods of implementing defenses against cross site scripting attack, the approach extracts all such defenses implemented in code so that developers, testers or auditors could check the extracted output to examine its adequacy. We have also evaluated the feasibility and effectiveness of the proposed approach by applying it to audit a set of real-world applications.
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Paper Nr: 65
Title:

A C++ CLASS FOR ANALYSING VECTOR BOOLEAN FUNCTIONS FROM A CRYPTOGRAPHIC PERSPECTIVE
Authors:

José A. Álvarez-Cubero and Pedro J. Zufiria
Abstract: In this paper, a C++ class for analising Vector Boolean Functions from a cryptographic perspective is presented. This implementation uses the NTL library from Victor Shoup, replacing some of the general purpose modules of this library by some more specialized and better suited to cryptography, and adding new modules that complement the existing ones. With this class, we can obtain the classical representation of Vector Boolean Function such as its Truth Table and Algebraic Normal Form (ANF). It is possible to calculate mathematical structures such as the Walsh Spectrum, Linear Profile, Differential Profile and Autocorrelation Spectrum. Cryptographic criteria such as nonlinearity, linearity distance, order of correlation immunity, balancedness, algebraic degree and propagation criterion can be obtained with this class. It permits to find out some interesting cryptologic parameters such as linear structures, linear potential, differential potential and the maximum possible nonlinearity or linearity distance of a Vector Boolean Function with the same dimensions. Finally, operations such as to identify if two Vector Boolean Functions are equal, their sum, direct sum, composition, bricklayering, adding coordinate functions and obtaining the polynomial representation over GF(2^n) of a Vector Boolean Function given the irreducible polynomial and its Truth Table are presented.
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Paper Nr: 142
Title:

Automated Threat Identification for UML
Authors:

George Yee, Xingli Xie and Shikharesh Majumdar
Abstract: In tandem with the growing important roles of software in modern society is the increasing number of threats to software. Building software systems that are resistant to these threats is one of the greatest challenges in information technology. Threat identification methods for secure software development can be found in the literature. However, none of these methods has involved automatic threat identification based on analyzing UML models. Such an automated approach should offer benefits in terms of speed and accuracy when compared to manual methods, and at the same time be widely applicable due to the ubiquity of UML. This paper addresses this shortcoming by proposing an automated threat identification method based on parsing UML diagrams.
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Area 2 - Access Control and Intrusion Detection

Full Papers
Paper Nr: 31
Title:

Risk Based Access Control with Uncertain and Time-dependent Sensitivity
Authors:

Juan Tapiador, John Clark, Dakshi Agrawal, John McDermid, Pau-Chen Cheng, Natalie Ivanic and David Slogget
Abstract: In traditional multi-level security (MLS) models, object labels are fixed assessments of sensitivity. In practice there will inevitably be some uncertainty about the damage that might be caused if a document falls into the wrong hands. Furthermore, unless specific management action is taken to regrade the label on an object, it does not change. This does not reflect the operational reality of many modern systems where there is clearly a temporal element to the actual sensitivity of information. Tactical information may be highly sensitive right now but comparatively irrelevant tomorrow whilst strategic secrets may need to be maintained for many years, decades, or even longer. In this paper we propose to model both security labels and clearances as probability distributions. We provide practical templates to model both uncertainty and temporally characterised dependencies, and show how these features can be naturally integrated into a recently proposed access control framework based on quantified risk.
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Paper Nr: 50
Title:

Handling IDSs' reliability in alert correlation: A Bayesian network-based model for handling IDS's reliability and controlling prediction/false alarm rate tradeoffs
Authors:

Karim Tabia and Philippe Leray
Abstract: Probabilistic graphical models are very efficient modeling and reasoning tools. In this paper, we propose an efficient and novel Bayesian network model for a major problem in alert correlation which plays a crucial role in nowadays computer security. Indeed, the use of multiple intrusion detection systems (IDSs) and complementary approaches is fundamental to improve the overall detection rates. This however inevitably rises huge amounts of alerts most of which are redundant and false alarms making the manual analysis of all the amounts of triggered alerts intractable. In this paper, we first propose a Bayesian network-based model allowing to handle the reliability of IDSs when predicting severe attacks by correlating the alerts reported by the IDSs monitoring the network. Then we propose a flexible and efficient approach especially designed to limit the false alarm rates by controlling the confidence of the prediction model. Finally, we provide experimental studies carried out on a real and representative alert corpus showing significant improvements regarding the tradeoffs between the prediction rates and the corresponding false alarm ones.
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Paper Nr: 113
Title:

A NOVEL INTRUSION DETECTION SYSTEM FOR MANETS
Authors:

Christoforos Panos, Christoforos Panos, Christos Xenakis and Ioannis Stavrakakis
Abstract: This paper proposes a novel Intrusion Detection System (IDS) for Mobile Ad Hoc Networks (MANETs) that aims at overcoming the limitations and weaknesses of the existing IDSs. The proposed IDS incorporates a novel random walk-based IDS architecture as well as a multi-layer, specification-based detection engine. The proposed solution does not belong to any of the existing intrusion detection approaches, since it relies on a set of robust, self-contained Random Walk Detectors (RWDs), which may freely move from node to node and randomly traverse a network, while monitoring each visiting node for malicious behaviour. RWDs exhibit a number of benefits including locality, simplicity, low overhead, and robustness to changes in topology. Moreover, the multi-layer, specification-based engine monitors the transport, network and data link layers of the protocol stack, providing an integrated solution capable of detecting the majority of security attacks occurring in MANETs.
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Short Papers
Paper Nr: 32
Title:

THE THREAT-VICTIM TABLE : A Security Prioritisation Framework For Diverse WLAN Network Topographies

Authors:

Author X, Author Y, Jonny Milliken and Alan Marshall
Abstract: At present there is no common means for establishing the security performance of wireless local area networks (WLANs) against threats. Furthermore, there has been little investigation into whether security performance is reliant on network topography. Consequently this paper advocates that for a range of WLAN infrastructure topographies (home, enterprise & open-access) there can be significant diversity in terms of resources, equipment, users and most importantly security, which can in turn influence attack detection performance. In order to demonstrate these detection differences, a novel framework for evaluating network security performance (the Threat-Victim Table) is developed. This framework is applied to a range of WLAN topographies using an open source (Kismet) Wireless Intrusion Detection System. Three Kismet components are utilised; client, server and drone, to represent typical IDS deployment configurations for these topographies. Analysis of the security capability of Kismet is derived as an example of this framework, for qualifying network security performance against security threats and also to assess the priority level of these vulnerabilities.
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Paper Nr: 35
Title:

Trust Degree Based Access Control for Social Networks
Authors:

Bo Lang
Abstract: Trust brings a new method for building scalable and fine-grained access control mechanism of social networks, a new kind of P2P systems. In this paper, the semantics of trust in the context of access control is described, and a Trust Degree Based Access Control model named TDBAC is proposed. Trust degree computing on a trust network is a key part in TDBAC. A novel algorithm that transforms a trust network to a computable expression is given. The algorithm simplifies the computation process and is also flexible.
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Paper Nr: 102
Title:

Efficient Algorithmic Safety Analysis of HRU Security Models
Authors:

Anja Fischer and Winfried Kühnhauser
Abstract: In order to achieve a high degree of security, IT systems with sophisticated security requirements increasingly apply security models for specifying, analyzing and implementing their security policies. While this approach achieves considerable improvements in effectiveness and correctness of a system's security properties, model specification, analysis and implementation are yet quite complex and expensive. This paper focuses on the efficient algorithmic safety analysis of HRU security models. We present the theory and practical application of a method that decomposes a model into smaller and autonomous sub-models that are more efficient to analyze. A recombination of the results then allows to infer safety properties of the original model. A security model for a real-world enterprise resource planning system demonstrates the approach.
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Paper Nr: 131
Title:

Side-channel attack on the HumanAuth CAPTCHA
Authors:

Carlos J. Hernández-Castro, Arturo Ribagorda Garnacho and Yago Saez
Abstract: We propose a new scheme of attack on the HumanAuth CAPTCHA which represents a significant shortcut to the intended attacking path, as it is not based in any advance in the state of the art on the field of image recognition. After analyzing the HumanAuth image database with a new approach based on statistical analysis and machine learning, we conclude that it cannot fulfill the security objectives intended by its authors. Then, we analyze which of the studied parameters for the image files seems to disclose the most valuable information for helping in correct classification, arriving at a surprising discovery. We also analyze if the image watermarking algorithm presented by the HumanAuth authors is able to counter the effect of this new attack. Our attack represents a completely new approach to breaking image labeling CAPTCHAs, and can be applied to many of the currently proposed schemes. Lastly, we investigate some measures that could be used to increase the security of image labeling CAPTCHAs as HumanAuth, but conclude no easy solutions are at hand.
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Paper Nr: 143
Title:

Rewriting-Based Security Enforcement Of concurrent systems : A formal Approach
Authors:

Mahjoub Langar, Mohamed Mejri and Kamel Adi
Abstract: The goal of program security enforcement approaches is to ensure that a program respects a given security policy that generally specifies acceptable executions of that program. In general, the enforcement is achieved by adding some controls (tests) inside the target program or process. The major drawback of existing techniques is either their lack of precision or their inefficiency, especially those dedicated for concurrent languages. In this paper, we propose an efficient algebraic and fully automatic approach for security program enforcement: given a concurrent program $P$ and a security policy $\phi$, we automatically generate another program $P'$ that satisfies $\phi$ and behaves like $P$, except that it stops when $P$ tries to violate the security policy $\phi$.
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Paper Nr: 9
Title:

Techniques for validation and controlled execution of processes, codes and data: A survey
Authors:

Dipankar Dasgupta, Sudip Saha and Aregahegn Negatu
Abstract: Various security mechanisms are available to validate, authenticate and permit codes, data and scripts for executing in a computing device. Accordingly, different techniques and tools have been developed to preserve integrity and confidentiality at the process, protocol, system and communication levels. For example, Trusted Platform Module, Intel Trusted Execution Technology and Windows Vista Kernel Mode security ensure system level integrity and security, whereas, Digital Signature, Code Signing, Watermarking, Integrity Checker and Magic Cookies address integrity of data and executables in transit. A brief survey of these techniques is described here with how these techniques help to secure computing environment.
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Paper Nr: 61
Title:

GRAPHICAL AUTHENTICATION BASED ON USER BEHAVIOUR
Authors:

Ahmed Al-Khazzar and Nick Savage
Abstract: In this paper the feasibility of having authentication systems based on user behaviour is studied. The approach used is based on psychological mechanisms of authentication which are a subset of a broader class of biometric mechanisms. This project implemented a 3D graphical system that a user has to navigate through. The user is authenticated based on information collected from their behaviour in reaction to the graphical system. Results obtained from the experiments revealed that this authentication system has an average accuracy of 88.33% in identifying different users from each other.
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Paper Nr: 82
Title:

Privacy Protection for User Authentication
Authors:

Jan Hajný, Tomas Pelka and Vaclav Zeman
Abstract: The paper deals with Internet user privacy. We focus on the protection of user identity during an Internet service use. We start with an overview of systems for the anonymous channel creation. Such channels are necessary as any solution for the identity protection will have to work with the TCP/IP protocols used in the Internet. In the second part of the paper we argue about the need for an anonymous authentication introduction. Such a service is almost missing in the current Internet. We show how the concept of anonymous authentication could improve privacy and identity protection. Finally we introduce our concept for anonymous authentication with the feature of a malicious user detection.
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Paper Nr: 100
Title:

INFINITE ALPHABET PASSWORDS A Unified Model for a Class of Authentication Systems
Authors:

Marcia Gibson, Marc Conrad and Carsten Maple
Abstract: In the paper we propose a formal model for class of authentication systems termed, “Infinite Alphabet Password Systems” (IAPs). We define such systems as those that use a character set for the construction of the authentication token that is theoretically infinite, only bound by practical implementation restrictions. We find that the IAP architecture can feasibly be adapted for use in many real world situations, and may be implemented using a number of system architectures and cryptographic protocols. A security analysis is conducted on an implementation of the model that utilizes images for its underlying alphabet. As a result of the analysis we find that IAPs can offer security benefits over traditional alphanumeric password schemes. In particular some of the significant problems concerning phishing, pharming, replay, dictionary and offline brute force attacks are mitigated.
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Paper Nr: 165
Title:

Piecewise Classification of Attack Patterns for Efficient Network Intrusion Detection

Authors:

Abdelhalim Zaidi, Zaidi Abdelhalim, Tayeb Kenaza and Agoulmine Nazim
Abstract: This paper presents a new scheme to improve the efficiency of pattern matching algorithms. The proposed approach is based on a piecewise classification of patterns using the common substrings. The main idea is to split the whole set of patterns into small subsets in accordance to the common substrings and treat the subsets independently. To reduce the number of patterns to match, we use the common substrings as an index for the search. We show that our algorihtm is capable to outcome in term of performance other reference algorithms, such as Aho-Corasick and Wu-Manber when the stream exhibits certain properties.
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Area 3 - Network Security and Protocols

Full Papers
Paper Nr: 39
Title:

Confidentiality and Integrity for sum aggregate in sensor networks
Authors:

Keith Frikken and Yihua Zhang
Abstract: When deploying sensor networks in environments that monitor people (e.g., monitoring water usage), both privacy and integrity are important. Several solutions have been proposed for privacy \cite{Castelluccia05}, \cite{Wenbo07}, and integrity \cite{Yang06}, \cite{Przydatek03}, \cite{Hu03}, \cite{Chan06}, \cite{Frikken08}. Unfortunately, these mechanisms are not easily composable. In this paper, we extend the splitting schemes proposed in \cite{Wenbo07} to provide privacy and integrity when computing the SUM aggregate. Our scheme provides privacy even if the base station colludes with some cluster heads, and provides integrity by detecting when individual nodes inflate or deflate their values too much. Our main contributions are: i) a new integrity measure that is a relaxation of the one in \cite{Chan06}, ii) a new privacy measure called $k$-similarity, iii) a construction that satisfies both of these measures for the computation of the SUM aggregate that avoids the usage of expensive cryptography, and iv) experimental results that demonstrate the effectiveness of our techniques. %For example, to provide privacy many prior schemes aggregate encrypted values, but this encryption prevents sanity checks, which are required by many of the previously proposed integrity mechanisms. The only work that addresses both privacy and integrity is \cite{Robert09}, which utilized monitoring nodes. This scheme %assumes that these monitoring sensors are honest, and if they become compromised the scheme does not achieve privacy or integrity. Further, this scheme does not prevent corrupted sensor nodes from corrupting the final aggregate result.
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Paper Nr: 85
Title:

QoS and Security in Energy-harvesting Wireless Sensor Networks
Authors:

Antonio Vincenzo Taddeo, Alberto Ferrante, Antonio V. Taddeo, Alberto Ferrante and Marcello Mura
Abstract: Wireless sensor networks are composed of small nodes that might be used for a variety of purposes. Nodes communicate together through a wireless connection that might be subject to different attacks when the network is placed in hostile environments. Furthermore, the nodes are usually equipped with very small batteries providing limited battery life, therefore limited power consumption is of utmost importance for nodes. This is in clear opposition with the requirement of providing security to communications as security might be very expensive from the power consumption stand point. Energy harvesting methods can be used to recharge batteries, but, in most of the cases the recharge profile cannot be known in advance. Therefore, nodes might face periods of time in which no recharge is available and the battery level is low. In this paper we introduce an optimization mechanism that allows the system to change the communication security settings at runtime with the goal of improving node lifetime, yet providing a suitable security level. The optimization mechanism further improves energy consumption by putting in place a quality of service mechanism: when energy is scarce, the system tends to send only essential packets. As shown by the simulations presented in this paper, this mechanism optimizes the energy consumption among different recharges.
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Paper Nr: 123
Title:

SECURE BRIDGING IN LARGE SCALE DEPLOYMENT OF ETHERNET
Authors:

Khan F. Wahid and Javier Rubio-Loyola
Abstract: Considering the dominance of Ethernet with upcoming 100 Gbps line rate, service providers want to reduce their transport networks to simpler Layer-2 networks. Since existing Ethernet security mechanisms protect links in hop-by-hop basis, they cannot control access for disloyal authorized users in virtual or logical shared media infrastructure LANs. Also they leave data in clear inside intermediate systems, which increase threats when these systems are placed in public places. To address these critical security issues, we propose an authenticated on-demand secure bridging solution that can provide a point-to-point secure channel between Ingress and Egress Bridges across Bridged Ethernet network. To build such secure channel, we use Identity-based authenticated key agreement and signature protocol. Experimental results using our prototype software on a small multi-segment Ethernet network suggest that our solution is feasible, and guarantees secure bridging.
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Short Papers
Paper Nr: 83
Title:

THROTTLING DDoS ATTACKS USING DISCRETE LOGARITHM PROBLEM
Authors:

Avinash Darapureddi, Radhesh Mohandas and Alwyn Pais
Abstract: Amongst all the security issues that the internet world is facing, Distributed Denial of Service attack (DDoS) receives special mention. In a typical DDoS attack, an attacker runs a malicious code on compromised systems to generate enormous number of requests to a single web server. The flood of incoming requests makes the victim web server resources to wear out completely within a short period of time; thereby causing denial of service to the legitimate users. In this paper we propose a solution to trim down the impact of DDoS attacks by throttling the client’s CPU i.e., to make clients pay a stamp fee which is collected in terms of resource usage such as CPU cycles. Our proposed solution makes use of the discrete logarithm problem to generate the CPU stamps.
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Paper Nr: 105
Title:

Realizing secure multiparty computation on incomplete networks
Authors:

Shailesh Vaya
Abstract: Secure multiparty computation of a multivariate function is a central problem in cryptography. It is well known that secure multiparty computation can be realized by a set of $n$ parties iff the connectivity of the underlying (authenticated) communication network is more than twice the number of corrupted parties. This impossibility result makes secure multiparty computation far less applicable in practice, as most deployed networks have a degree much lower than $O(n)$ and one would ideally like to be able to tolerate $\Theta(n)$ corrupted parties. In this work we consider a recently proposed model for (Unconditional) secure multiparty computation for networks of low degrees for which authenticated channels are available only between very few pairs of parties. Not all honest parties may be expected to achieve traditional security guarantees of multiparty computation for this model because of theoretical limitations posed by lack of infrastructure. Honest parties which are not given canonical guarantees of Correctness and Privacy are called "sacrificed" and the resulting notion is called almost everywhere secure computation. In this conceptual note, we investigate the previous results about this model by Garay and Ostrovsky,2008. We explain why these results hold only for weak honest-but-curious type passive corruptions. We emphasize why the results for almost everywhere secure computation are theoretically interesting and practically relevant only when active malicious corruptions are allowed. We argue the limitation of hybrid argument, for realizing privacy property when Byzantine corruptions are allowed. From this we deduce that simulation based reduction approach is necessary to realize even input indistinguishability type definition of privacy for the stand alone setting. We present a conceptual exposition of the simulator based approach for defining privacy of a.e.s.c.. Finally, we present a brief overview of technicalities involved in realizing a.e.s.c. when malicious corruptions are allowed.
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Paper Nr: 107
Title:

SECURITY IN FUTURE MOBILE SENSOR NETWORKS Issues and Challenges

Authors:

George Hadjichristofi, George Hadjichristofi, Andreas Pitsillides, Eliana Stavrou and Christoforos Hadjicostis
Abstract: Existing security research in wireless sensor networks is based on specific assumptions about the nodes and the network environment that are tied to specific usage scenarios. Typical scenarios consider sensor nodes that are immobile and have pre-defined communication patterns. We argue that node mobility is a realistic characteristic of sensor nodes that needs to be taken into consideration in future sensor networks. Mobility capabilities can address the objective challenges raised in mission-critical applications, such as in disaster relief, where their environment characteristics fluctuate over time. It is imperative to investigate the way security is affected in mobile sensor networks and identify the challenges that will need to be addressed in future security protocol design. We present our vision for future sensor networks through a realistic scenario and discuss security gaps that are present in existing in research for next generation sensor networks.
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Paper Nr: 130
Title:

Providing Confidentiality in Content-based Publish/Subscribe Systems
Authors:

Bruno Crispo, Mihaela Ion and Giovanni Russello
Abstract: The publish/subscribe model offers a loosely-coupled communication paradigm where applications interact indirectly and asynchronously. Publisher applications generate events that are sent to interested applications through a network of brokers. Subscriber applications express their interest by specifying filters that brokers can use for routing the events. Supporting confidentiality of messages being exchanged is still challenging. First of all, it is desirable that any scheme used for protecting the confidentiality of both the events and filters should not require the publishers and subscribers to share secret keys. In fact, such a restriction is against the loose-coupling of the model. Moreover, such a scheme should not restrict the expressiveness of filters and should allow the broker to perform event filtering to route the events to the interested parties. Existing solutions do not fully address those issues. In this paper, we provide a novel scheme that supports (i) confidentiality for events and filters; (ii) filters can express very complex constraints on events even if brokers are not able to access any information on both events and filters; (iii) and finally it does not require publishers and subscribers to share keys.
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Paper Nr: 28
Title:

What can RFID do for VANETs? A cryptographic point of view
Authors:

Alberto Peinado, Andres Ortiz and Jorge Munilla
Abstract: Vehicular ad hoc networks (VANETs) are becoming more popular as a way to increase the traffic safety and comfort. Radio Frequency Technology (RFID) is widely deployed for supply-chain and inventory management, retail operations and more generally automatic identification. Not unexpectedly, it is being pointed out that the inclusion of RFID technology in the VANETs architecture could enable the development of interesting new services and improve the overall results. However, in addition to the typical problems of RFID systems, new challenges arise in this scenario (RFID-VANETs) that must be solved. More specifically this paper analyzes the security aspects of these applications, where the traditional cryptographic protocols previously proposed for RFID are not suitable. After discussing the threats and the security requirements, the paper provides the most relevant guidelines to secure this kind of systems.
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Paper Nr: 80
Title:

FORMAL VERIFICATION OF G-PAKE USING CASPER/FDR2
Authors:

Mihai L. Pura, Victor V. Patriciu and Bica Ion
Abstract: Research in security of ad hoc networks consists mainly of classifications and new protocol propositions. But formal verification should also be used in order to be able to prove the properties intended for the protocols. In this paper we present our work in formally verifying the group password-based authenticated key exchange protocol proposed in 2000 by Asokan and Ginzboorg. The proposition is rather old, but in the last years the research community focused only on two-party PAKE protocols, giving very little attention to group PAKE protocols. With the help of Casper and FDR2 we prove that G-PAKE does not accomplish the specifications given by the authors. Based on our results we proposed an improved version that we validated through model checking.
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Paper Nr: 87
Title:

ShortECC: a Lightweight Security Approach for Wireless Sensor Networks
Authors:

Anna Sojka-Piotrowska, Piotrowski Krzysztof and Peter Langendörfer
Abstract: This paper presents our ongoing work towards a new lightweight security approach for Wireless Sensor Networks. Applying several changes in the standard Elliptic Curve Cryptography parameter sets and algorithms we get a public/secret key hybrid with a reasonable security level and much shorter key sizes. Here we present the main idea, the algorithms together with the initial security analysis and the directions for the future research.
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Paper Nr: 121
Title:

ULTRA HIGH SPEED SHA-256 HASHING CRYPTOGRAPHIC MODULE FOR IPSEC HARDWARE/SOFTWARE CODESIGN
Authors:

George Athanasiou, Harris Michail, Angeliki Kritikakou, George Athanasiou, Andreas Gregoriades, Costas Goutis and Vicky Papadopoulou
Abstract: Nowadays, more than ever, security is considered to be critical issue for all electronic transactions. This is the reason why security services like those described in IPSec are mandatory to IPV6 which will be adopted as the new IP standard the next years. Moreover the need for security services in every data packet that is transmitted via IPv6, illustrates the need for designing security products able to achieve higher throughput rates for the incorporated security schemes. In this paper such a design is presented which manages to increase throughput of SHA-256 hash function enabling efficient software/hardware co-design.
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Paper Nr: 146
Title:

Efficient Asymmetric IPsec for Secure iSCSI
Authors:

C. E. Chow and Murthy Andukuri
Abstract: In this paper we propose a new asymmetric IPsec scheme to enhance the security of data at the remote end, while simultaneously improving the overall performance. The idea is to apply IPsec encryption/decryption in a segmented manner on the iSCSI traffic, such that the user data remains encrypted after leaving the sender, and is decrypted only when it is retrieved by the sender. A dual key cryptographic scheme is proposed where the private key is used to encrypt the iSCSI payload at the sender and traditional IPsec is modified to encrypt/decrypt only on the TCP/iSCSI headers. A development test bed was built using User-Mode-Linux virtual machines for developing and debugging the asymmetric IPsec software and running as the sender and receiver to verify the functionality and security features of the proposed design. A benchmark test bed was built with two real PCs where the asymmetric IPsec modules can be dynamically loaded. The performance results show that the existing implementation of the proposed asymmetric IPsec scheme reduces the IPsec processing time by about 25%.
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Paper Nr: 164
Title:

SECURITY MODELS FOR HETEROGENEOUS NETWORKING
Authors:

Mahdi Aiash, Glenford Mapp, Raphael Phan and Aboubaker Lasebae
Abstract: Security for Next Generation Networks (NGN) is an attractive topic for many research groups. The Y-Comm security group believes that a new security approach is needed to address the security challenges in 4G networks. This paper sheds light on our approach of providing security for the Y-Comm architecture as an example of 4G communication frameworks. Our approach proposes a four-layer security integrated module to protect data and three targeted security models to protect different network entities, thus providing security in different situations without affecting the dynamics of the 4G networks.
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Area 4 - Cryptographic Techniques and Key Management

Full Papers
Paper Nr: 26
Title:

Analysis of SNOW 3G$^{\oplus}$ Resynchronization Mechanism
Authors:

Bin Zhang, Deike Priemuth-Schmid and Alex Biryukov
Abstract: The stream cipher SNOW 3G designed in 2006 by ETSI/SA-GE is a base algorithm for the second set of 3GPP confidentiality and integrity algorithms. This paper is the first attempt of cryptanalysis of this algorithm in the public literature. We look at SNOW 3G in which two modular additions are replaced by xors, which is called SNOW 3G$^{\oplus}$. We show that the feedback from the FSM to the LFSR is very important, since we can break a version without such a feedback using a pair of \textit{known} IVs with practical complexities ($2^{57}$ time and $2^{33}$ keystream). We then extend this technique into a differential \textit{chosen} IV attack on SNOW 3G$^{\oplus}$ and show how to break $16$ out of $33$ rounds with the feedback.
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Paper Nr: 42
Title:

On A Construction of Stream-cipher-based Hash Functions
Authors:

Yuto Nakano, Jun Kurihara, Shinsaku Kiyomoto and Toshiaki Tanaka
Abstract: Hash functions using stream ciphers as components perform fast on a variety of platforms. However, the security and the design policy of stream-cipher-based hash functions (SCHs) have not yet been studied sufficiently. In this paper, we analyze its design criteria based on a ideal function of SCHs. First, we show that attacks against a stream cipher can also be threats against SCHs. Then we discuss the security on each phase of SCH; message injection, blank rounds, and hash generation with this function. Finally we derive the necessary conditions on the stream cipher function for an SCH to be secure.
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Paper Nr: 73
Title:

PROXIABLE DESIGNATED VERIFIER SIGNATURE
Authors:

Mebae Ushida, Yutaka Kawai, Kazuki Yoneyama and Kazuo Ohta
Abstract: Designated Verifier Signature (DVS) guarantees that only a verifier designated by a signer can verify the “validity of signature”. In this paper, we propose a new variant of DVS; Proxiable Designated Verifier Signature (PDVS) where the verifier can make a third party (i.e. the proxy) substitute some process of the verification. In the PDVS system, the verifier can reduce his computational cost by delegating some process of the verification without revealing the validity of signature to the proxy. In all DVS systems, the validity of signature means that a signature satisfies both properties that (1) the signature is judged “accept” by a decision algorithm and (2) the signature is confirmed that it is generated by the signer. So in the PDVS system, the verifier can make the proxy substitute checking only the property of (1). In the proposed PDVS model, we divide verifier’s secret keys into two parts; one is a key for performing the decision algorithm, and the other is a key for generating a dummy signature, which prevents a third party from convincing the property (2). We also define security requirements for the PDVS, and propose a PDVS scheme which satisfies all security requirements we define.
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Paper Nr: 79
Title:

Adaptive and Composable Non-interactive String-Commitment Protocols
Authors:

Huafei Zhu, Tadashi Araragi, Takashi Nishide and Kouichi Sakurai
Abstract: In this paper, a non-interactive string-commitment protocol in the common reference string reusable model without erasure is presented and analyzed. We show that the proposed (length-flexible) commitment protocol realizes the universally composable security in the presence of adaptive adversaries in the standard computational model assuming that the underlying Paillier's public-key encryption (or Damg\aa rd and Jurik's public-key encryption scheme when a length-flexible property is claimed) is semantically secure and the Damg{\aa}rd-Fazio-Nicolosi's non-interactive protocol is zero-knowledge in the registered public-key model.
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Paper Nr: 81
Title:

Identity Based Ring Signcryption with Public Verifiability
Authors:

Sakhi. S. Anand, S. S. Vivek, S. D. Selvi, C.Pandu Rangan, S.Harmila S., S. S. Vivek, Sakhi S and Pandu R. C.
Abstract: Signcryption is a cryptographic primitive which offers authentication and confidentiality simultaneously with a cost lower than signing and encrypting the message independently. Ring signcryption enables a user to anonymously signcrypt a message on behalf of a set of users including himself. Thus a ring signcrypted message has anonymity in addition to authentication and confidentiality. Ring signcryption schemes have no centralized coordination: any user can choose a ring of users, that includes himself and signcrypt any message without any assistance from the other group members. Ring Signcryption is useful for leaking trustworthy secrets in an anonymous, authenticated and confidential way. To the best of our knowledge, ten identity based ring signcryption schemes are reported in the literature. Three of them were proved to be insecure in \cite{FMT08}, \cite{ZhangGCG09} and \cite{SSP09}. Four of them were proved to be insecure in \cite{SelviVR09}. In this paper, we show that one among the remaining three schemes, \cite{ZhangZYZ09} is not secure against confidentiality, existential unforgeability and anonymity attacks. We propose a new anonymous ring signcryption scheme which is an extension to \cite{SelviVR09} and give formal security proofs for our system in the random oracle model. Our scheme is publicly verifiable which none of the existing unbroken schemes can achieve.
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Paper Nr: 89
Title:

Server-assisted long-term secure 3-party key establishment
Authors:

Rainer Steinwandt and Kashi Neupane
Abstract: Consider a scenario where a server S shares a symmetric key k_U with each user U. Building on a 2-party solution of Bohli et al., we describe an authenticated 3-party key establishment which remains secure if a computational Bilinear Diffie Hellman problem is hard or the server is uncorrupted. If the BDH assumption holds during a protocol execution, but is invalidated later, entity authentication and integrity of the protocol are still guaranteed.
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Paper Nr: 92
Title:

Forcing out a confession: Threshold Discernible Ring Signatures

Authors:

Swarun Kumar, Shivank Agrawal, Ramarathnam Venkatesan, Satya Lokam and Pandu R. C.
Abstract: Ring signature schemes (Rivest et al., 2001) enable a signer to sign a message and remain hidden within an arbitrary group A of n people, called a ring. The signer may choose this ring arbitrarily without any setup procedure or the consent of anyone in A. Among several variations of the notion, step out ring signatures introduced in (Klonowski et al., 2008) address the issue of a ring member proving that she is not the original signer of a message, in case of dispute. First we show that the scheme in (Klonowski et al., 2008) has several flaws and design a correct scheme and prove formally the security of the same. Then we use the basic constructs of our scheme to design a protocol for a new problem, which we refer to as threshold discernible ring signatures. In threshold discernible ring signatures, a group B of t members can co-operate to identify the original signer of a ring signature that involved a group A of n alleged signers, where B is a subset of A and n > t. This is the first time that this problem is considered in the literature and we formally prove the security of our novel scheme in the random oracle model.
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Paper Nr: 94
Title:

Universally Composable Non-committing Encryptions in the Presence of Adaptive Adversaries
Authors:

Huafei Zhu, Tadashi Araragi, Takashi Nishide and Kouichi Sakurai
Abstract: Designing non-committing encryptions tolerating adaptive adversaries is a challenging task. In this paper, a simple implementation of non-committing encryptions is presented and analyzed in the strongest security model. We show that the proposed non-committing encryption scheme is provably secure against adaptive adversaries in the universally composable framework assuming that the decisional Diffie-Hellman problem is hard.
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Paper Nr: 135
Title:

An Encryption Scheme For a Secure Access Policy Updating
Authors:

Luan Ibraimi, Milan Petkovic and Muhammad Asim
Abstract: Ciphertext policy attribute based encryption is an encryption technique where the data is encrypted according to an access policy over attributes (e.g. doctor and nurse); hence only users who have a secret key associated with a set of attributes which satisfy the access policy can decrypt the encrypted data. However, one of the drawback of the CP-ABE scheme is that it does not support updating access control policy without decrypting the encrypted data. We present a new variant of the CP-ABE scheme called ciphertext policy attribute based proxy re-encryption (CP-ABPRE) which allows updating access control policy of the encrypted data. The scheme uses a semi-trusted entity called proxy which employs a re-encryption key created by the user to re-encrypt the data according to a new policy without decrypting the ciphertext such that only users who satisfy the new policy can decrypt the data. The construction of our scheme is based on prime order bilinear groups. We give a formal definition for semantic security and provide a security proof in the generic group model.
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Short Papers
Paper Nr: 19
Title:

CONJUGATION AS PUBLIC KEY AGREEMENT PROTOCOL IN MOBILE CRYPTOGRAPHY

Authors:

Vittorio Ottaviani, Alberto Zanoni and Massimo Regoli
Abstract: We analyze a key agreement algorithm realization, not using Diffie-Hellman approach, but using matrix powers and conjugation. Introduced in a theoretical frame by Sakalauskas et. al. in 2007, it is here implemented in J2ME on mobile devices (Nokia N70 equipped with Symbian S60 operating system). We study its appliability and performances and compare them with Elliptic Curve and standard Diffie-Hellman Bouncy Castle implementation, freely available on the web.
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Paper Nr: 14
Title:

Vulnerability Of A Non-Membership Proof Scheme
Authors:

Kun Peng and Feng Bao
Abstract: An accumulator system used for a special application of anonymous credential is extended by Li et al to a much wider range of applications: membership proof and non-membership proof. Given a committed secret integer and a public finite set of prime integers, two proof protocols, membership proof and non-membership proof are proposed in the extended scheme. The former proves that the integer is in the set when it is really in, while the latter proves that the integer is not in the set when it is really not in. Although the original accumulator technique works well in its appointed special application, the extension is insecure and vulnerable to attacks. Several attacks against membership proof and non-membership proof in the extended work is proposed in this paper to show its vulnerability in security. The attacks show that an attacker can employ various methods to give membership proof to an integer not in the set and non-membership proof to an integer in the set.
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Paper Nr: 37
Title:

Extended Visual Cryptography Scheme for Color Images with No Pixel Expansion
Authors:

Xiaoyu Wu, Duncan S. Wong and Qing Li
Abstract: A k-out-of-n Extended Visual Cryptography Scheme (EVCS) is a secret sharing scheme which hides a secret image into n shares, which are also some images. The secret image can be recovered if at least k of the shares are superimposed, while nothing can be obtained if less than k shares are known. Previous EVCS schemes are either for black-and-white images or having pixel expansion. In this paper, we propose the first k-out-of-n EVCS for color images with no pixel expansion. The scheme also improves the contrast of the n shares and the reconstructed secret image (i.e. the superimposed image of any k or more shares) by allowing users to specify the level of each primary color (i.e. Red, Green and Blue) in the image shares as well as the reconstructed secret image.
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Paper Nr: 43
Title:

New Pseudo near collision attack on Tiger
Authors:

Debdeep Mukhopadhyay, Dibyendu Mallik, Dibyendu Mallik and Debdeep Mukhopadhyay
Abstract: Tiger is a cryptographic hash function created by Anderson and Biham in 1996 with hash value of 192 bits. Reduced round variants of Tiger have shown some weaknesses recently. Kelsey and Lucks have shown a collision attack on Tiger reduced to round 16 and 17. Mendel and Rijmen have found 1 bit pseudo near collision for full round Tiger . In this article we discover a new key schedule differential for Tiger which leads to the finding of message pairs for 1-bit pseudo near collision.
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Paper Nr: 124
Title:

BMQE System: A MQ Equations System Based on Ergodic Matrix
Authors:

Yongzhe Zhao, Wencai Du and Xiaoyi Zhou
Abstract: In this paper, we propose a multivariate quadratic (MQ) equation system based on ergodic matrix (EM) over a finite field with q elements (denoted as F^q). The system actually implicates a problem which is equivalent to the famous Graph Coloring problem, and therefore is NP complete for attackers. The complexity of bisectional multivariate quadratic equation (BMQE) system is determined by the number of the variables, of the equations and of the elements of F^q, which is denoted as n, m, and q, respectively. The paper shows that, if the number of the equations is larger or equal to twice the number of the variables, and qn is large enough, the system is complicated enough to prevent attacks from most of the existing attacking schemes.
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Area 5 - Information Assurance

Short Papers
Paper Nr: 72
Title:

On the Importance of One-Time Key Pairs in Buyer-Seller Watermarking Protocols
Authors:

David Williams, Anthony TS Ho and Helen Treharne
Abstract: In this paper we emphasise the importance of unique certified one-time key pairs in Buyer-Seller Watermarking (BSW) protocols. We distinguish between reactive unbinding attacks, in which the seller reacts to illicit file sharing by fabricating further evidence of such activity, and pre-emptive unbinding attacks, in which the seller gains an advantage by taking action that pre-empts the file being shared. We demonstrate the importance of certified one-time key pairs in the BSW protocol by Lei et al., for protecting against pre-emptive unbinding attacks, and subsequently reveal a new attack on a recently published BSW protocol due to its omission of unique key pairs.
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Paper Nr: 112
Title:

HUBFIRE - A MULTI-CLASS SVM BASED JPEG STEGANALYSIS USING HBCL STATISTICS AND FR INDEX
Authors:

Veena Bhat, Krishna S, P. D. Shenoy, Venugopal K. R., Venugopal K. R. and L. M. Patnaik
Abstract: Blind Steganalysis attempts to detect steganographic data without prior knowledge of either the embedding algorithm or the ‘cover’ image. This paper proposes new features for JPEG blind steganalysis using a combination of Huffman Bit Code Length (HBCL) Statistics and File size to Resolution ratio (FR Index); the Huffman Bit - File Index Resolution (HUBFIRE) algorithm proposed here, uses these functionals to build the classifier using a multi-class Support Vector Machine (SVM). JPEG images spanning a wide range of resolutions are used to create a ‘stego-image’ database employing three embedding schemes – the advanced Least Significant Bit encoding technique, that embeds in the spatial domain, a transform-domain embedding scheme: JPEG Hide-and-Seek and Model Based Steganography which employs an adaptive embedding technique. This work employs a multi-class SVM over the proposed ‘HUBFIRE’ algorithm for statistical steganalysis, which is not yet explored by steganalysts. Experiments conducted prove the model’s accuracy over a wide range of payloads and embedding schemes.
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Paper Nr: 71
Title:

A NEW CHAOS-BASED WATERMARKING ALGORITHM
Authors:

Christophe Guyeux and Jacques M. Bahi
Abstract: This paper introduces a new watermarking algorithm based on discrete chaotic iterations. After defining some coefficients deduced from the description of the carrier medium, chaotic discrete iterations are used to mix the watermark and to embed it in the carrier medium. It can be proved that this procedure generates topological chaos, which ensures that desired properties of a watermarking algorithm are satisfied.
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Paper Nr: 114
Title:

AN ICT SECURITY MANAGEMENT FRAMEWORK
Authors:

Aristeidis Chatzipoulidis and Ioannis Mavridis
Abstract: Recently, organizations started to realize that managing information security is more than a software solution; it is a strategic discipline. This realization has emerged a major challenge in the business and technology field, the integration of all governance, risk, and compliance (GRC) activities to operate in synergy and balance in configuration with the business and security objectives. The goal of this paper is to develop a comprehensive ICT security management framework as a unified platform against the evolving GRC complexity. Considering the endemic nature of risk, the risk approach requires periodical rethinking in order to keep pace with security changes and prevent undesirable incidents while preserving the stakeholders’ interests continuously. Such an approach depends on the risk management maturity level, and the portfolio of monitoring controls.
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Area 6 - Data and Application Security and Privacy

Full Papers
Paper Nr: 25
Title:

AN EFFECTIVE CLUSTERING APPROACH TO WEB QUERY LOG ANONYMIZATION
Authors:

Ke Wang and Ke Wang
Abstract: Query log data contain information useful to research; however, release of such data can seriously breach the privacy of search engine users. These privacy concerns go far beyond the explicitly identifying information in a query such as name and address, since non-identifying personal data can be combined with external publicly available information to pinpoint to an individual. In this work we model query logs as unstructured transaction data and present a novel transaction anonymization technique based on clustering and generalization to achieve the k-anonymity privacy. We conduct extensive experiments on the AOL query log data. Our results show that this method results in a higher data utility compared to the best current transaction data anonymization method.
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Paper Nr: 69
Title:

ANONYMOUS SUBSCRIPTION SCHEMES: A Flexible Construction for On-line Services Access
Authors:

Maria I. González Vasco, Somayeh Heidarvand and Jorge Villar
Abstract: In traditional e-cash systems, the tradeoff between anonymity and fraud-detection is solved by hiding the identity of the user into the e-coin, and providing an additional triggering mechanism that opens this identity in case of double spending. Hence, fraud detection implies loss of anonymity. This seems to be a somewhat natural solution when universality of the e-coin is required (i.e., the use of the coin is not determined at the time the coin is generated). However, much simpler protocols may suffice if we only want to prevent that payments for accessing certain services are over-used, even when users' anonymity is perfectly preserved. In this paper we propose a simple and efficient Subscription Scheme, allowing a set of users to anonymously pay for and request access to different services off ered by a number of service providers. In our approach, the use of the token is completely determined at issuing time, yet this fi nal aim remains hidden to the issuing authority. Moreover, fraud detection here implies no loss of anonymity; as we make access tokens independent of the owner in a quite simple and efficient way. On the other hand, if diff erent usages of the same token are allowed, these are fully traceable by the service providers.
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Paper Nr: 133
Title:

Anonymous But Authorized Transactions Supporting Selective Traceability
Authors:

Daniel Slamanig and Stefan Rass
Abstract: While privacy was more or less neglected in the early days of the Internet, in recent years it has emerged to be a hot topic in computer security research. Among other reasons, since the use of the Internet is becoming more and more ubiquitous, cloud computing emerges and consequently users provide a lot of information to potentially untrusted third parties. In this paper we propose an approach which provides a means for users to anonymously conduct transactions with a service-provider such that those transactions can neither be linked to a specific user nor linked together. At the same time, a service-provider can be sure that only authorized users are able to conduct transactions. In particular, we bring together the concepts of anonymous authentication from public-key encryption and anonymous as well as unlinkable token based transactions in order to profit from the advantages of the two single approaches. Since full anonymity is usually not desirable, we provide mechanism to identify misbehaving anonymous users behind transactions. More precisely, we realize selective traceability, which allows revocation of the anonymity of a suspicious users along with the identification of all of her transactions, without violating the privacy of all remaining users.
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Paper Nr: 144
Title:

DON’T FOLLOW ME: SPAM DETECTION IN TWITTER
Authors:

Alex H. Wang
Abstract: The rapidly growing social network Twitter has been infiltrated by large amount of spam. In this paper, a spam detection prototype system is proposed to identify suspicious users on Twitter. A directed social graph model is proposed to explore the “follower” and “friend” relationships among Twitter. Based on Twitter’s spam policy, novel content-based features and graph-based features are also proposed to facilitate spam detection. A Web crawler is developed relying on API methods provided by Twitter. Around 25K users, 500K tweets, and 49M follower/friend relationships in total are collected from public available data on Twitter. Bayesian classification algorithm is applied to distinguish the suspicious behaviors from normal ones. I analyze the data set and evaluate the performance of the detection system. Classic evaluation metrics are used to compare the performance of various traditional classification methods. Experiment results show that the Bayesian classifier has the best overall performance in term of F-measure. The trained classifier is also applied to the entire data set. The result shows that the spam detection system can achieve 89% precision.
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Short Papers
Paper Nr: 16
Title:

“MY SMARTPHONE IS A SAFE!” - The user’s point of view regarding novel authentication methods and gradual security levels on smartphones

Authors:

Tim Dörflinger, Anna Voth, Juliane Krämer and Ronald Fromm
Abstract: This paper addresses laboratory tests regarding a graded security system on smartphones based on novel authentication methods. However, the main scope of this paper is not the technical dimension of such a system but rather the user’s perception of and the need for it. In November 2009 we conducted four focus groups with a total of n=19 respondents with the goal to evaluate different prototypical authentication methods for smartphones and to determine the effects such methods would have for the user’s interaction with the devices. The focus groups were part of a larger research program at Deutsche Telekom Laboratories that included a web survey measuring general user preferences regarding security and smartphone usage as well as the development of prototypical authentication methods based on Google’s “Android” operating system. The goal of this research was to integrate the user into the development process as soon as possible and to determine the overall acceptance of new authentication methods, such as biometric authentication, but also 2D and 3D gestures, recognition based authentication and password authentication. This paper gives valuable insights on the weakest link of the security chain: the user.
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Paper Nr: 41
Title:

Safe RPC - Auditing mixnets safely using Randomized Partial Checking
Authors:

Eugen Leontie, Stefan Popoveniuc and Eugen Leontie
Abstract: Secure voting systems like PunchScan and Scantegrity use mixnets which are verified using Randomized Partial Checking (RPC). This simple and efficient technique can lead to privacy loss and may, in an extreme case, result in linking all the clear text ballots to the voters who cast them, thus completely destroying the secrecy of all ballots and circumventing the functionality of the mixnet. We suggest a simple technique, Secure RPC (SRPC), that uses RPC in a way that guarantees maximal privacy in all possible cases. We prove that SRPC does not asymptotically reduce the integrity offered by RPC.
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Paper Nr: 108
Title:

EnCoRe: Towards a Holistic Approach to Privacy
Authors:

Nick Papanikolaou, Sadie Creese, Siani Pearson, Marco Casassa Mont and Michael Goldsmith
Abstract: Privacy requirements for IT systems and solutions arise from a variety of sources, including legislation, sector-specific regulation, organisational guidelines, social and user expectations. In this paper we present and discuss a holistic approach to the management of privacy - explored in the context of the EnCoRe project - which takes into account the need to deal with these different types of policies, at different levels of abstraction as well as risk assessment methods to assess them based on specific threats, needs and constraints. We discuss examples of privacy requirements and related policies coming from different sources. We then present how a ‘privacy-aware risk assessment’ approach (which leverages and extends traditional security-driven risk assessment approaches) can be used to analyse these policies, assess their compliance to requirements, identify gaps and mandate the adoption of specific controls. We explain its relevance and implications in an employee data case study, involving the management of privacy consent and revocation. This is work in progress, carried out in the context of the EnCoRe collaborative project.
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Paper Nr: 119
Title:

Preventing Malicious Portlets from Communicating and Intercepting in Collaboration Portals
Authors:

Oliver Gmelch and Günther Pernul
Abstract: In a “networked enterprise”, distributed teams of partner organizations, humans, computer applications, autonomous robots, and devices are interlinked to collaborate with each other in order to achieve higher productivity and to perform joint projects or produce joint products that would have been impossible to develop without the contributions of multiple collaborators. Within a collaboration, security aspects are of critical importance. This is in particular true for loosely coupled collaborations in which individual members of one alliance are working with each other within a certain project only, but may be competitors in other market fields at the same time. Going beyond the current state of the art in portal-based collaboration platforms, this paper presents an approach to prevent unintended information disclosure by malicious portlet instances. The solution is built on open standards (JSR 286 and XACML) and may be incorporated in collaboration-wide enterprise portals in order to regulate information flow during inter-portlet communication.
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Paper Nr: 129
Title:

Anonymous Social Stamps: Authenticating anonymous statements to friends with privacy
Authors:

Sandeep Kumar
Abstract: Numerous online services and applications for smart devices exist today on the internet which claim almost similar functionalities. This inevitably leads to the problem of being able to choose the right one which is mostly done today by trial-and-error. However this gets tricky if it involves sharing privacy sensitive information with the service e.g. in the case of health and well-ness services. A customer's trust in a new online service is known to increase based on testimonials (or observable behavior) of people within a social distance (friends, friends-of-friends etc). Linking testimonials to users requires releasing one's social network information which by itself is privacy invasive. The paper presents the concept of an \textit{anonymous social stamp} which can be assigned to anonymous statements and help prove that the statement was made by a particular member of an external social networking site. Trust can then be derived based on the social distance between the persons concerned: the person who made the statement and the person verifying the statement. A possible implementation of the concept is shown with the existing infrastructure of RSA keys already in use by social networking sites. The concept is applicable for the new services that can create confidence in new users by revealing anonymous data sharing configurations of other users with the service.
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Paper Nr: 141
Title:

Implications of Misbehaving attacks on Probabilistic Quorum System for MANETs
Authors:

Michele N. Lima, Elisa Mannes, Eduardo da Silva and Aldri Santos
Abstract: Reliable storage supports different data sharing services, such as mobility management, cryptographic key management and distributed naming or addressing services. Mobile Ad hoc NETworks (MANETs) present issues in guaranteeing the consistency of data on concurrent read and write accesses due to their characteristics as dynamism of nodes, and the inexistence of a central control entity or support infrastructure. Probabilistic quorum systems, as PAN (Probabilistic Ad Hoc Network Quorum Systems), were designed for MANETs as a mechanism to improve the efficiency of data replication by relaxing consistency constraints. Quorum systems comprise a set of quorums intersecting among themselves in order to ensure availability and consistency properties, and to guarantee that nodes obtain the most recent value. PAN is more appropriated for MANETs due to the use of less strict rules for creating intersections among quorum. It ensures high probability of consistency between reading and writing operations on replicated data by an asymmetric quorum construction and by a gossip-based multicast protocol. However, PAN does not consider the presence of malicious or selfish nodes in its operations. Hence, this work assesses the impact of lack of cooperation, timing and data manipulation attacks against PAN using two metrics as reliability degree and percentage of malicious nodes on reading operations. Simulation results show that PAN is vulnerable to these attacks, particularly, data manipulation, in which the system correctly conclude only 2% of reading operations when submitted to 30% of attackers.
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Paper Nr: 148
Title:

HTEE: an HMAC based Tamper Evident Encryption
Authors:

Bradley Baker, C. E. Chow and Brad Baker
Abstract: This paper presents a HMAC based Temper Evident Encryption (HTEE) technique for providing confidentiality and integrity of numeric data in a database environment through an encryption scheme based on the keyed Hash Message Authentication Code (HMAC) function. The encryption scheme implemented in this project extends and improves an existing HMAC based encryption scheme. The result is a symmetric encryption process which detects unauthorized updates to ciphertext data, verifies integrity and provides confidentiality. This encryption scheme provides an alternative to standard approaches that offer confidentiality and integrity of data such as combining the Advanced Encryption Standard (AES) algorithm with a hash digest. The purpose of the scheme is to provide a straightforward and efficient encryption that supports data integrity, to investigate the use of HMAC for reversible encryption and key transformation, and to improve upon an existing method.
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Paper Nr: 20
Title:

IMPROVING N-GRAM LINGUISTIC STEGANOGRAPHY BASED ON TEMPLATES.
Authors:

Alfonso Muñoz, Irina Argüelles and Justo Carracedo
Abstract: The automatic generation of stegotexts is an area of research within linguistic steganography with a great interest. Different proposals have been published about the development of stegotexts with statistical and linguistic validity in natural language but, unfortunately, the stegotexts generated following some of these procedures suffer from different types of lexical, syntactic, semantic problems or problems of global coherence that would eventually lead the automatically generated texts to be detected by a human reader. This article presents an improved implementation of an algorithm of N-Gram statistic imitation and introduces a new concept of manual edition of the stegotexts generated, based on the idea of templates. This procedure permits the creation of high quality stegotexts to hide a small quantity of information, hundreds of bits, useful to distribute a symmetrical key, a short message, an url, etc. The procedure developed in the article can be applied to different languages, but here, its usefulness is demonstrated for Spanish. The Stelin tool is presented free at http://stelin.sourceforge.net.
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Paper Nr: 84
Title:

Towards data protection compliance
Authors:

Nicola Zannone , Milan Petkovic and Sandro Etalle
Abstract: Privacy and data protection are fundamental issues nowadays for every organization. This paper calls for the development of methods, techniques and infrastructure to allow the deployment of privacy-aware IT systems, in which humans are integral part of the organizational processes and accountable for their possible misconduct. In particular, we discuss the challenges to be addressed in order to improve organizations' privacy practices, as well as the approach to ensure compliance with legal requirements and increasing efficiency.
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Paper Nr: 103
Title:

TOWARDS RISK BASED PREVENTION OF GROOMING ATTACKS
Authors:

Dimitrios Michalopoulos and Ioannis Mavridis
Abstract: The increasing incidents of children sexual exploitation through cyberspace demand for proper protection with technological defense mechanisms. This paper aims to present and evaluate methods and tools that are appropriate towards the prevention of child sexual abuse through Internet based communications. Attacking categories and strategies that predators follow are analyzed and modeled. Moreover, a comparative review of existing risk modeling methods, which is based on a set of proposed criteria, is presented. This comparison results in the conclusion that only two of the reviewed risk modeling methods can be adapted on the intended grooming attack detection system: Bayesian and Markovian. The proposed approach is concluded with a discussion on particular methods and tools for accurate attack probability calculation.
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Paper Nr: 161
Title:

ANONYMOUS SERVICES - Enhancing End-User Privacy Exploiting Anonymous Networks
Authors:

Giovanni Cabiddu, Emanuele Cesena and Davide Vernizzi
Abstract: The large number of online services poses serious problems to users' privacy. The sole confidentiality of data exchanged is not enough for complete privacy because an external observer may learn sensitive information simply by observing the communication channel, even if it is not possible to access the actual data transmitted. In this position paper, we propose a solution where user privacy is guaranteed by providing anonymous access to the services. Our solution is based on a service gateway, an anonymous credential system, an authentication protocol and an anonymous network. We designed the solution to be cost-effective and scalable; moreover, we employ existing standard protocols whenever possible to facilitate development and deployment.
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