Biblio

This paper targets the efficient implementation of digital signatures and signcryption schemes on typical internet-of-things (IoT) devices, i.e. embedded processors with constrained computation power and storage. Both signcryption schemes (providing digital signatures and encryption simultaneously) and digital signatures rely on computation-intensive public-key cryptography. When the number of signatures or encrypted messages the device needs to generate after deployment is limited, a trade-off can be made between performing the entire computation on the embedded device or moving part of the computation to a precomputation phase. The latter results in the storage of the precomputed values in the memory of the processor. We examine this trade-off on a health sensor platform and we additionally apply storage encryption, resulting in five implementation variants of the considered schemes.

For a computing platform that is compliant with the Trusted Platform Module (TPM) standard, direct anonymous attestation (DAA) is an appropriate cryptographic protocol for realizing an anonymous subscription system. This approach takes advantage of a cryptographic key that is securely embedded in the platform's hardware, and enables privacy-preserving authentication of the platform. In all of the existing DAA schemes, the platform suffers from significant computational and communication costs that increase proportionally to the size of the revocation list. This drawback renders the existing schemes to be impractical when the size of the revocation list grows beyond a relatively modest size. In this paper, we propose a novel scheme called Lightweight Anonymous Subscription with Efficient Revocation (LASER) that addresses this very problem. In LASER, the computational and communication costs of the platform's signature are multiple orders of magnitude lower than the prior art. LASER achieves this significant performance improvement by shifting most of the computational and communication costs from the DAA's online procedure (i.e., signature generation) to its offline procedure (i.e., acquisition of keys/credentials). We have conducted a thorough analysis of LASER's performance related features. We have implemented LASER on a laptop with an on-board TPM. To the best of our knowledge, this is the first implementation of a DAA scheme on an actual TPM cryptoprocessor that is compliant with the most recent TPM specification, viz., TPM 2.0.

Research has demonstrated promising benefits of applying virtual trainers to promote physical fitness. The current study investigated the value of virtual agents in the context of personal fitness, compared to trainers with greater levels of perceived agency (avatar or live human). We also explored the possibility that the effectiveness of the virtual trainer might depend on the affective tone it uses when trying to motivate users. Accordingly, participants received either positively or negatively valenced motivational messages from a virtual human they believed to be either an agent or an avatar, or they received the messages from a human instructor via skype. Both self-report and physiological data were collected. Like in-person coaches, the live human trainer who used negatively valenced messages were well-regarded; however, when the agent or avatar used negatively valenced messages, participants responded more poorly than when they used positively valenced ones. Perceived agency also affected rapport: compared to the agent, users felt more rapport with the live human trainer or the avatar. Regardless of trainer type, they also felt more rapport - and said they put in more effort - with trainers that used positively valenced messages than those that used negatively valenced ones. However, in reality, they put in more physical effort (as measured by heart rate) when trainers employed the more negatively valenced affective tone. We discuss implications for human–computer interaction.

Secure group-oriented communication is crucial to a wide range of applications in Internet of Things (IoT). Security problems related to group-oriented communications in IoT-based applications placed in a privacy-sensitive environment have become a major concern along with the development of the technology. Unfortunately, many IoT devices are designed to be portable and light-weight; thus, their functionalities, including security modules, are heavily constrained by the limited energy resources (e.g., battery capacity). To address these problems, we propose a group key management scheme based on a novel physically unclonable function (PUF) design: multistage interconnected PUF (MIPUF) to secure group communications in an energy-constrained environment. Our design is capable of performing key management tasks such as key distribution, key storage and rekeying securely and efficiently. We show that our design is secure against multiple attack methods and our experimental results show that our design saves 47.33% of energy globally comparing to state-of-the-art Elliptic-curve cryptography (ECC)-based key management scheme on average.

In this paper, a new image encryption algorithm is presented with one chaotic map and one group of secret keys. Double permutations for pixel positions are designed followed by a function of diffusion to alter gray distribution in the plain-image. In the proposed algorithm, the keystream is produced and dependent on the plain-image. As a result, the method can frustrate the known plaintext attack and chosen plaintext attack. Moreover, diffusion encryption by row-only is applied to the permuted image to save time consumption. Then, the experimental results show that our method can perform high security and is suitable for both gray and color images.

Location Privacy breach in Wireless Sensor Networks (WSNs) cannot be controlled by encryption techniques as all the communications are signal based. Signal strength can be analyzed to reveal many routing information. Adversary takes advantage of this and tracks the incoming packet to know the direction of the packet. With the information of location of origin of packets, the Source is also exposed which is generating packets on sensing any object. Thus, the location of subject is exposed. For protecting such privacy breaches, routing schemes are used which create anonymization or diverts the adversary. In this paper, we are using `Dummy' packets that will be inserted into real traffic to confuse the adversary. The dummy packets are such inserted that they encircle the Sink or Base Station. These Dummy packets are send with a value of TTL (Time To Live) field such that they travel only a few hops. Since adversary starts backtracking from the Sink, it will be trapped in the dummy traffic. In our protocol, we are confusing adversary without introducing any delay in packet delivery. Adversary uses two common methods for knowing the source i.e. Traffic Analysis and Back-tracing. Mathematically and experimentally, our proposal is sound for both type of methods. Overhead is also balanced as packets will not live long.

Nowadays, some workplaces have adopted the policy of BYOD (bring your own device) that permits employees to bring personally owned devices, and to use those devices to access company information and applications. Especially, small devices like smartphones are widely used due to the greater mobility and connectivity. A majority of organizations provide the wireless local area network which is necessary for small devices and business data transmission. The resources access through Wi-Fi network of the organization needs intense restriction. WPA2 Enterprise with 802.1X standard is typically introduced to handle user authentication on the network using the EAP framework. However, credentials management for all users is a hassle for administrators. Strong authentication provides higher security whereas the difficulty of deployment is still open issues. This research proposes the utility of Near Field Communication to securely transmit certificate data that rely on the hybrid cryptosystem. The approach supports enterprise Wi-Fi hotspot authentication based on WPA2-802.1X model with the EAP-TLS method. It also applies multi-factor authentication for enhancing the security of networks and users. The security analysis and experiment on establishing connection time were conducted to evaluate the presented approach.

In this paper, we present an embodied conversational agent (ECA) that includes a cognitive-affective architecture based on the Soar cognitive architecture, integrates an emotion model based on ALMA that uses a three-layered model of emotions, mood and personality, from the point of view of the user and the agent. These features allow to modify the behavior and personality of the agent to achieve a more realistic and believable interaction with the user. This ECA works as a virtual assistant to search information from Wikipedia and show personalized results to the user. It is only a prototipe, but can be used to show some of the possibilities of the system. A first evaluation was conducted to prove these possibilities, with satisfactory results that also give guidance for some future work that can be done with this ECA.

Successful attacks on computer networks today do not often owe their victory to directly overcoming strong security measures set up by the defender. Rather, most attacks succeed because the number of possible vulnerabilities are too large for humans to fully protect without making a mistake. Regardless of the security elsewhere, a skilled attacker can exploit a single vulnerability in a defensive system and negate the benefits of those security measures. This paper presents an evolutionary framework for evolving attacker agents in a real, emulated network environment using genetic programming, as a foundation for coevolutionary systems which can automatically discover and mitigate network security flaws. We examine network enumeration, an initial network reconnaissance step, through our framework and present results demonstrating its success, indicating a broader applicability to further cyber-security tasks.

The widescale use of machine learning algorithms to drive decision-making has highlighted the critical importance of ensuring the interpretability of such models in order to engender trust in their output. The state-of-the-art recommendation systems use black-box latent factor models that provide no explanation of why a recommendation has been made, as they abstract their decision processes to a high-dimensional latent space which is beyond the direct comprehension of humans. We propose a novel approach for extracting explanations from latent factor recommendation systems by training association rules on the output of a matrix factorisation black-box model. By taking advantage of the interpretable structure of association rules, we demonstrate that predictive accuracy of the recommendation model can be maintained whilst yielding explanations with high fidelity to the black-box model on a unique industry dataset. Our approach mitigates the accuracy-interpretability trade-off whilst avoiding the need to sacrifice flexibility or use external data sources. We also contribute to the ill-defined problem of evaluating interpretability.

Currently, fusing visible and thermal images for facial expression recognition requires two modalities during both training and testing. Visible cameras are commonly used in real-life applications, and thermal cameras are typically only available in lab situations due to their high price. Thermal imaging for facial expression recognition is not frequently used in real-world situations. To address this, we propose a novel thermally enhanced facial expression recognition method which uses thermal images as privileged information to construct better visible feature representation and improved classifiers by incorporating adversarial learning and similarity constraints during training. Specifically, we train two deep neural networks from visible images and thermal images. We impose adversarial loss to enforce statistical similarity between the learned representations of two modalities, and a similarity constraint to regulate the mapping functions from visible and thermal representation to expressions. Thus, thermal images are leveraged to simultaneously improve visible feature representation and classification during training. To mimic real-world scenarios, only visible images are available during testing. We further extend the proposed expression recognition method for partially unpaired data to explore thermal images' supplementary role in visible facial expression recognition when visible images and thermal images are not synchronously recorded. Experimental results on the MAHNOB Laughter database demonstrate that our proposed method can effectively regularize visible representation and expression classifiers with the help of thermal images, achieving state-of-the-art recognition performance.

Climate change represents a serious threat to the health of our planet and imposed a discussion upon energy waste and production. In this paper we propose a smart grid architecture relying on blockchain technology aimed at discouraging the production and distribution of non-renewable energy as the one derived from fossil fuel. Our model relies on a reverse application of a recently introduced attack to the blockchain based on chain forking. Our system involves both a central authority and a number of distributed peers representing the stakeholders of the energy grid. This system preserves those advantages derived from the blockchain and it also address some limitations such as energy waste for mining operations. In addition, the reverse attack we rely on allows to mitigate the behavior of a classic blockchain, which is intrinsecally self-regulated, and to trigger a sort of ethical action which penalizes non-renewable energy producers. Blacklisted stakeholders will be induced to provide their transaction with higher fees in order to preserve the selling rate.

Image registration is the process of aligning images of the same scene taken at different instances, from different viewpoints or by heterogeneous sensors. This can be achieved either by area based or by feature based image matching techniques. Feature based image registration focuses on detecting relevant features from the input images and attaching descriptors to these features. Matching visual descriptions of two images is a major task in image registration. This feature matching is currently done using Exhaustive Search (or Brute-Force) and Nearest Neighbour Search. The traditional method used for nearest neighbour search is by representing the data as k-d trees. This nearest neighbour search can also be performed using combinatorial optimization algorithms such as Simulated Annealing. This work proposes a method to perform image feature matching by nearest neighbour search done based on Threshold Accepting, a faster version of Simulated Annealing.The experiments performed suggest that the proposed algorithm can produce better results within a minimum number of iterations than many existing algorithms.

The generative and transformative nature of the Internet which has become a synonym for the infrastructure of the contemporary digital society, is also a place where there are unsavoury and illegal activities such as fraud, human trafficking, exchange of control substances, arms smuggling, extremism, and terrorism. The legitimate concerns such as anonymity and privacy are used for proliferation of nefarious deeds in parts of the Internet termed as a deep web and a dark web. The cryptographic and anonymity mechanisms employed by the dark web miscreants create serious problems for the law enforcement agencies and other legal institutions to monitor, control, investigate, prosecute, and prevent the range of criminal events which should not be part of the Internet, and the human society in general. The paper describes the research on developing a framework for identifying, collecting, analysing, and reporting information from the dark web in a forensically sound manner. The framework should provide the fundamentals for creating a real-life system that could be used as a tool by law enforcement institutions, digital forensics researchers and practitioners to explore and study illicit actions and their consequences on the dark web. The design science paradigms is used to develop the framework, while international security and forensic experts are behind the ex-ante evaluation of the basic components and their functionality, the architecture, and the organization of the system. Finally, we discuss the future work concerning the implementation of the framework along with the inducement of some intelligent modules that should empower the tool with adaptability, effectiveness, and efficiency.

The complex architecture of browser technologies and dynamic characteristics of JavaScript make it difficult to ensure security in client-side web applications. Browser-level security policies alone are not sufficient because it is difficult to apply them correctly and they can be bypassed. As a result, they need to be completed by application-level security policies. In this paper, we survey existing solutions for specifying and enforcing application-level security policies for client-side web applications, and distill a number of desirable features. Based on these features we developed Guardia, a framework for declaratively specifying and dynamically enforcing application-level security policies for JavaScript web applications without requiring VM modifications. We describe Guardia enforcement mechanism by means of JavaScript reflection with respect to three important security properties (transparency, tamper-proofness, and completeness). We also use Guardia to specify and deploy 12 access control policies discussed in related work in three experimental applications that are representative of real-world applications. Our experiments indicate that Guardia is correct, transparent, and tamper-proof, while only incurring a reasonable runtime overhead.

The occurrence of security vulnerabilities in kernel, especially for macOS/iOS kernel XNU, has increased rapidly in recent years. Naturally, concerns were raised due to the high risks they would lead to, which in general are much more serious than common application vulnerabilities. However, discovering XNU kernel vulnerabilities is always very challenging, and the main approach in practice is still manual analysis, which obviously is not a scalable method. In this paper, we perform an in-depth empirical study on the 406 published XNU kernel vulnerabilities to identify distinguishing characteristics of them and then leverage the features to guide our vulnerability detection, i.e., locating suspicious functions. To further improve the efficiency of vulnerability detection, we present KInspector, a new and lightweight framework to detect XNU kernel vulnerabilities by leveraging feedback-based fuzzing techniques. We thoroughly evaluate our approach on XNU with various versions, and the results turn out to be quite promising: 21 N/0-day vulnerabilities have been discovered in our experiments.

This work describes a three-times (\$3$\backslash$times\$) improvement to the performance of secure computation of AES over a network of three parties with an honest majority. The throughput that is achieved is even better than that of computing AES in some scenarios of local (non-private) computation. The performance improvement is achieved through an optimization of the generic secure protocol, and, more importantly, through an optimization of the description of the AES function to support more efficient secure computation, and an optimization of the protocol to the underlying architecture. This demonstrates that the development process of efficient secure computation must include adapting the description of the computed function to be tailored to the protocol, and adapting the implementation of the protocol to the architecture. This work focuses on the secure computation of AES since it has been widely investigated as a de-facto standard performance benchmark for secure computation, and is also important by itself for many applications. Furthermore, parts of the improvements are general and not specific to AES, and can be applied to secure computation of arbitrary functions.

HYDRA is an automated mechanism to repair code in response to successful attacks. Given a set of malicious inputs that include the attack and a set of benign inputs that do not, along with an ability to test the victim application with these labelled inputs, HYDRA quickly provides rank ordered patches to close the exploited vulnerability. HYDRA also produces human-readable summaries of its findings and repair actions to aid the manual vulnerability mitigation process. We tested HYDRA using 8 zero-days, HYDRA produced patches that stopped the attacks in all 8 cases and preserved application functionality in 7 of the 8 cases.

Low-power wide area networks (LPWANs), such as LoRa, are fast emerging as the preferred networking technology for large-scale Internet of Things deployments (e.g., smart cities). Due to long communication range and ultra low power consumption, LPWAN-enabled sensors are today being deployed in a variety of application scenarios where sensitive information is wirelessly transmitted. In this work, we study the privacy guarantees of LPWANs, in particular LoRa. We show that, although the event-based duty cycling of radio communication, i.e., transmission of radio signals only when an event occurs, saves power, it inherently leaks information. This information leakage is independent of the implemented crypto primitives. We identify two types of information leakage and show that it is hard to completely prevent leakage without incurring significant additional communication and computation costs.

Mobile network operators choose Self Organizing Network (SON) concept as a cost-effective method to deploy LTE/4G networks and meet user expectations for high quality of service and bandwidth. The main objective of SON is to introduce automation into network management activities and reduce human intervention. SON enabled LTE networks heavily rely on the information acquired from mobile phones to provide self-configuration, self-optimization, and self-healing features. However, mobile phones can be attacked over-the-air using rogue base stations. In this paper, we carefully study SON related LTE/4G security specifications and reveal several vulnerabilities. Our key idea is to introduce a rogue eNodeB that uses legitimate mobile devices as a covert channel to launch attacks against SON enabled LTE networks. We demonstrate low-cost, practical, silent and persistent Denial of Service attacks against the network and end-users by injecting fake measurement and configuration information into the SON system. An active attacker can shut down network services in 2 km2 area of a city for a certain period of time and also block network services to a selective set of mobile phones in a targeted area of 200 m to 2 km in radius. With the help of low cost tools, we design an experimental setup and evaluate these attacks on commercial networks. We present strategies to mitigate our attacks and outline possible reasons that may explain why these vulnerabilities exist in the system.

Conference and journal publications increasingly require experiments associated with a submitted article to be repeatable. Authors comply to this requirement by sharing all associated digital artifacts, i.e., code, data, and environment configuration scripts. To ease aggregation of the digital artifacts, several tools have recently emerged that automate the aggregation of digital artifacts by auditing an experiment execution and building a portable container of code, data, and environment. However, current tools only package non-distributed computational experiments. Distributed computational experiments must either be packaged manually or supplemented with sufficient documentation. In this paper, we outline the reproducibility requirements of distributed experiments using a distributed computational science experiment involving use of message-passing interface (MPI), and propose a general method for auditing and repeating distributed experiments. Using Sciunit we show how this method can be implemented. We validate our method with initial experiments showing application re-execution runtime can be improved by 63% with a trade-off of longer run-time on initial audit execution.

Collaborative trajectory privacy preservation (CTPP) scheme is an effective method for continuous queries. However, collaborating with other users need pay some cost. Therefore, some rational and selfish users will not choose collaboration, which will result in users' privacy disclosing. To solve the problem, this paper proposes a collaboration incentive mechanism by rewarding collaborative users and punishing non-collaborative users. The paper models the interactions of users participating in CTPP as a repeated game and analysis the utility of participated users. The analytical results show that CTPP with the proposed incentive mechanism can maximize user's payoffs. Experiments show that the proposed mechanism can effectively encourage users' collaboration behavior and effectively preserve the trajectory privacy for continuous query users.

Vehicular ad-hoc networks (VANETs) are designed to play a key role in the development of future transportation systems. Although cooperative awareness messages provide the required situational awareness for new safety and efficiency applications, they also introduce a new attack vector to compromise privacy. The use of ephemeral credentials called pseudonyms for privacy protection was proposed while ensuring the required security properties. In order to prevent an attacker from linking old to new pseudonyms, mix-zones provide a region in which vehicles can covertly change their signing material. In this poster, we extend the idea of mix-zones to mitigate pseudonym linking attacks with a mechanism inspired by chaff-based privacy defense techniques for mix-networks. By providing chaff trajectories, our system restores the efficacy of mix-zones to compensate for a lack of vehicles available to participate in the mixing procedure. Our simulation results of a realistic traffic scenario show that a significant improvement is possible.

Creating and maintaining an up-to-date set of security rules that match misuses of crypto APIs is challenging, as crypto APIs constantly evolve over time with new cryptographic primitives and settings, making existing ones obsolete. To address this challenge, we present a new approach to extract security fixes from thousands of code changes. Our approach consists of: (i) identifying code changes, which often capture security fixes, (ii) an abstraction that filters irrelevant code changes (such as refactorings), and (iii) a clustering analysis that reveals commonalities between semantic code changes and helps in eliciting security rules. We applied our approach to the Java Crypto API and showed that it is effective: (i) our abstraction effectively filters non-semantic code changes (over 99% of all changes) without removing security fixes, and (ii) over 80% of the code changes are security fixes identifying security rules. Based on our results, we identified 13 rules, including new ones not supported by existing security checkers.

Owing1 to an immense growth of internet-connected and learning-enabled cyber-physical systems (CPSs) [1], several new types of attack vectors have emerged. Analyzing security and resilience of these complex CPSs is difficult as it requires evaluating many subsystems and factors in an integrated manner. Integrated simulation of physical systems and communication network can provide an underlying framework for creating a reusable and configurable testbed for such analyses. Using a model-based integration approach and the IEEE High-Level Architecture (HLA) [2] based distributed simulation software; we have created a testbed for integrated evaluation of large-scale CPS systems. Our tested supports web-based collaborative metamodeling and modeling of CPS system and experiments and a cloud computing environment for executing integrated networked co-simulations. A modular and extensible cyber-attack library enables validating the CPS under a variety of configurable cyber-attacks, such as DDoS and integrity attacks. Hardware-in-the-loop simulation is also supported along with several hardware attacks. Further, a scenario modeling language allows modeling of alternative paths (Courses of Actions) that enables validating CPS under different what-if scenarios as well as conducting cyber-gaming experiments. These capabilities make our testbed well suited for analyzing security and resilience of CPS. In addition, the web-based modeling and cloud-hosted execution infrastructure enables one to exercise the entire testbed using simply a web-browser, with integrated live experimental results display.