Minimizing information leakage of tree-based RFID authentication protocols using alternate tree-walking

The privacy of efficient tree-based RFID authentication protocols is heavily dependent on the branching factor on the top layer. Indefinitely increasing the branching factor, however, is not a viable option. This paper proposes the alternate-tree walking scheme as well as two protocols to circumvent this problem. The privacy of the resulting protocols is shown to be comparable to that of linear-time protocols, where there is no leakage of information, whilst reducing the computational load of the database by one-third of what is required of tree-based protocols during authentication. We also identify and address a limitation in quantifying privacy in RFID protocols

Forward-secure hierarchical predicate encryption

Secrecy of decryption keys is an important pre-requisite for security of any encryption scheme and compromised private keys must be immediately replaced. \emph{Forward Security (FS)}, introduced to Public Key Encryption (PKE) by Canetti, Halevi, and Katz (Eurocrypt 2003), reduces damage from compromised keys by guaranteeing confidentiality of messages that were encrypted prior to the compromise event. The FS property was also shown to be achievable in (Hierarchical) Identity-Based Encryption (HIBE) by Yao, Fazio, Dodis, and Lysyanskaya (ACM CCS 2004). Yet, for emerging encryption techniques, offering flexible access control to encrypted data, by means of functional relationships between ciphertexts and decryption keys, FS protection was not known to exist.\smallskip In this paper we introduce FS to the powerful setting of \emph{Hierarchical Predicate Encryption (HPE)}, proposed by Okamoto and Takashima (Asiacrypt 2009). Anticipated applications of FS-HPE schemes can be found in searchable encryption and in fully private communication. Considering the dependencies amongst the concepts, our FS-HPE scheme implies forward-secure flavors of Predicate Encryption and (Hierarchical) Attribute-Based Encryption.\smallskip Our FS-HPE scheme guarantees forward security for plaintexts and for attributes that are hidden in HPE ciphertexts. It further allows delegation of decrypting abilities at any point in time, independent of FS time evolution. It realizes zero-inner-product predicates and is proven adaptively secure under standard assumptions. As the ``cross-product" approach taken in FS-HIBE is not directly applicable to the HPE setting, our construction resorts to techniques that are specific to existing HPE schemes and extends them with what can be seen as a reminiscent of binary tree encryption from FS-PKE

Denial-of-Service Resistance in Key Establishment

Denial of Service (DoS) attacks are an increasing problem for network connected systems. Key establishment protocols are applications that are particularly vulnerable to DoS attack as they are typically required to perform computationally expensive cryptographic operations in order to authenticate the protocol initiator and to generate the cryptographic keying material that will subsequently be used to secure the communications between initiator and responder. The goal of DoS resistance in key establishment protocols is to ensure that attackers cannot prevent a legitimate initiator and responder deriving cryptographic keys without expending resources beyond a responder-determined threshold. In this work we review the strategies and techniques used to improve resistance to DoS attacks. Three key establishment protocols implementing DoS resistance techniques are critically reviewed and the impact of misapplication of the techniques on DoS resistance is discussed. Recommendations on effectively applying resistance techniques to key establishment protocols are made

Denial of Service in Voice Over IP Networks

In this paper we investigate denial of service (DoS) vulnerabilities in Voice over IP (VoIP) systems, focusing on the ITU-T H.323 family of protocols. We provide a simple characterisation of DoS attacks that allows us to readily identify DoS issues in H.323 protocols. We also discuss network layer DoS vulnerabilities that affect VoIP systems. A number of improvements and further research directions are proposed

The genus Camelobaetidius Demoulin (Ephemeroptera: Baetidae) in America: Phylogenic and biogeographic analyses

The genus Camelobaetidius is the second most diverse genus of the family Baetidae in America. Also, two other genera were described as closely related to Camelobaetidius: Corinnella, and Tapajobaetis. A peculiar spatulate tarsal claw is the character shared among them. We used TNT (Tree analysis using New Technology) and GEM (Geographically explicit Event Model) to recover the phylogenic and biogeographic history of these genera. A matrix of 42 taxa and 77 morphological characters was constructed, of which 68 were treated as discrete and nonadditive (unordered), and eight as continuous. All available records of Camelobaetidius plus Corinnella, Tapajobaetis, and the species's outgroup were included in the biogeographic analysis. Corinnella and Tapajobaetis were obtained into Camelobaetidius and, therefore, are here considered junior synonyms. The founder events were the most frequent in this genus, followed by vicariance, sympatry and point sympatry. The long-distance dispersal ability in mayfly seems to be the rule instead of the exception in the history of this clade.Fil: Nieto Peñalver, María Carolina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Instituto de Biodiversidad Neotropical. Universidad Nacional de Tucumán. Facultad de Ciencias Naturales e Instituto Miguel Lillo. Instituto de Biodiversidad Neotropical. Instituto de Biodiversidad Neotropical; ArgentinaFil: Boldrini, Rafael. Universidade Federal de Roraima. Centro de Estudos da Biodiversidade; BrasilFil: Gonzalez, Juan Cruz. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Instituto de Biodiversidad Neotropical. Universidad Nacional de Tucumán. Facultad de Ciencias Naturales e Instituto Miguel Lillo. Instituto de Biodiversidad Neotropical. Instituto de Biodiversidad Neotropical; ArgentinaFil: Pes, Ana Maria. Ministério da Ciência, Tecnologia, Inovações. Instituto Nacional de Pesquisas da Amazônia; BrasilFil: Falcao Salles, Frederico. Universidade Federal de Viçosa. Departamento de Entomologia. Museu de Entomologia; Brasi

SAR measurements of coastal features in the NW Mediterranean

Peer ReviewedPostprint (published version

How HCI Design Influences Web Security Decisions

ABSTRACT Even though security protocols are designed to make computer communication secure, it is widely known that there is potential for security breakdowns at the humanmachine interface. This paper reports on a diary study conducted in order to investigate what people identify as security decisions that they make while using the web. The study aimed to uncover how security is perceived in the individual's context of use. From this data, themes were drawn, with a focus on addressing security goals such as confidentiality and authentication. This study is the first study investigating users' web usage focusing on their self-documented perceptions of security and the security choices they made in their own environment

Chapter On the Optical Response of Nanoparticles: Directionality Effects and Optical Forces

Organic chemistr

Towards Secure and Legal E-Tendering

Tendering processes are considered to be a suitable mechanism for governments to fairly assign contracts for construction projects and procurement. The demand for efficiencies to be created in the process has resulted in a significant number of governments implementing e-tendering systems. E-tendering systems generally involve the submission of tender offer documents to a secure system hosted by the government (principal). An electronic environment presents obvious opportunities for collusion between principal and certain tenderers, fraud by tenderers and a minefield of legal uncertainties for fuelling protracted disputes. Critical examination of the security and legal requirements for e-tendering systems does not appear in the current literature. This paper identifies key security and legal issues to be addressed in the design of e-tendering systems, which may be included in e-procurement software, and proposes a new e-tendering architecture, using distributed trusted third parties which may be suitable for secure large scale operations such as the construction industry