Biblio

The fast and energy-efficient simulation of dynamical systems defined by coupled ordinary/partial differential equations has emerged as an important problem. The accelerated simulation of coupled ODE/PDE is critical for analysis of physical systems as well as computing with dynamical systems. This paper presents a fast and programmable accelerator for simulating dynamical systems. The computing model of the proposed platform is based on multilayer cellular nonlinear network (CeNN) augmented with nonlinear function evaluation engines. The platform can be programmed to accelerate wide classes of ODEs/PDEs by modulating the connectivity within the multilayer CeNN engine. An innovative hardware architecture including data reuse, memory hierarchy, and near-memory processing is designed to accelerate the augmented multilayer CeNN. A dataflow model is presented which is supported by optimized memory hierarchy for efficient function evaluation. The proposed solver is designed and synthesized in 15nm technology for the hardware analysis. The performance is evaluated and compared to GPU nodes when solving wide classes of differential equations and the power consumption is analyzed to show orders of magnitude improvement in energy efficiency.

Apps written in JavaScript are an easy target for reverse engineering attacks, e.g. to steal the intellectual property or to create a clone of an app. Unprotected JavaScript apps even contain high level information such as developer comments, if those were not explicitly stripped. This fact becomes more and more important with the increasing popularity of JavaScript as language of choice for both web development and hybrid mobile apps. In this paper, we present a novel JavaScript obfuscator based on the Google Closure Compiler, which transforms readable JavaScript source code into a representation much harder to analyze for adversaries. We evaluate this obfuscator regarding its performance impact and its semantics-preserving property.

Summary form only given. Authentication of people or objects using physical keys is insecure against secret duplication. Physical unclonable functions (PUF) are special physical keys that are assumed to be unclonable due to the large number of degrees of freedom in their manufacturing [1]. Opaque scattering media, such as white paint and teeth, comprise of millions of nanoparticles in a random arrangement. Under coherent light illumination, the multiple scattering from these nanoparticles gives rise to a complex interference resulting in a speckle pattern. The speckle pattern is seemingly random but highly sensitive to the exact position and size of the nanoparticles in the given piece of opaque scattering medium [2], thereby realizing an ideal optical PUF. These optical PUFs enabled applications such as quantum-secure authentication (QSA) and communication [3, 4].

The public cloud is moving to a Platform-as-a-Service model where services such as data management, machine learning or image classification are provided by the cloud operator while applications are written in high-level languages and leverage these services. Managed languages such as Java, Python or Scala are widely used in this setting. However, while these languages can increase productivity, they are often associated with problems such as unpredictable garbage collection pauses or warm-up overheads. We argue that the reason for these problems is that current language runtime systems were not initially designed for the cloud setting. To address this, we propose seven tenets for designing future language runtime systems for cloud data centers. We then outline the design of a general substrate for building such runtime systems, based on these seven tenets.

The continuous discovery of exploitable vulnerabilitiesin popular applications (e.g., web browsers and documentviewers), along with their heightening protections against control flow hijacking, has opened the door to an oftenneglected attack strategy-namely, data-only attacks. In thispaper, we demonstrate the practicality of the threat posedby data-only attacks that harness the power of memorydisclosure vulnerabilities. To do so, we introduce memorycartography, a technique that simplifies the construction ofdata-only attacks in a reliable manner. Specifically, we showhow an adversary can use a provided memory mapping primitive to navigate through process memory at runtime, andsafely reach security-critical data that can then be modifiedat will. We demonstrate this capability by using our cross-platform memory cartography framework implementation toconstruct data-only exploits against Internet Explorer and Chrome. The outcome of these exploits ranges from simple HTTP cookie leakage, to the alteration of the same originpolicy for targeted domains, which enables the cross-originexecution of arbitrary script code. The ease with which we can undermine the security ofmodern browsers stems from the fact that although isolationpolicies (such as the same origin policy) are enforced atthe script level, these policies are not well reflected in theunderlying sandbox process models used for compartmentalization. This gap exists because the complex demands oftoday's web functionality make the goal of enforcing thesame origin policy through process isolation a difficult oneto realize in practice, especially when backward compatibility is a priority (e.g., for support of cross-origin IFRAMEs). While fixing the underlying problems likely requires a majorrefactoring of the security architecture of modern browsers(in the long term), we explore several defenses, includingglobal variable randomization, that can limit the power ofthe attacks presented herein.

Searchable Symmetric Encryption is a mechanism that facilitates search over encrypted data that are outsourced to an untrusted server. SSE schemes are practical as they trade nicely security for efficiency. However, the supported functionalities are mainly limited to single keyword queries. In this paper, we present a new efficient SSE scheme, called REX, that supports range queries. REX is a no interactive (single round) and response-hiding scheme. It has optimal communication and search computation complexity, while it is much more secure than traditional Order Preserving Encryption based range SSE schemes.

Locally Linear Embedding (LLE) is a popular approach to dimensionality reduction as it can effectively represent nonlinear structures of high-dimensional data. For dimensionality reduction, it computes a nearest neighbor graph from a given dataset where edge weights are obtained by applying the Lagrange multiplier method, and it then computes eigenvectors of the LLE kernel where the edge weights are used to obtain the kernel. Although LLE is used in many applications, its computation cost is significantly high. This is because, in obtaining edge weights, its computation cost is cubic in the number of edges to each data point. In addition, the computation cost in obtaining the eigenvectors of the LLE kernel is cubic in the number of data points. Our approach, Ripple, is based on two ideas: (1) it incrementally updates the edge weights by exploiting the Woodbury formula and (2) it efficiently computes eigenvectors of the LLE kernel by exploiting the LU decomposition-based inverse power method. Experiments show that Ripple is significantly faster than the original approach of LLE by guaranteeing the same results of dimensionality reduction.

At present, Bluetooth Low Energy (BLE) is dominantly used in commercially available Internet of Things (IoT) devices – such as smart watches, fitness trackers, and smart appliances. Compared to classic Bluetooth, BLE has been simplified in many ways that include its connection establishment, data exchange, and encryption processes. Unfortunately, this simplification comes at a cost. For example, only a star topology is supported in BLE environments and a peripheral (an IoT device) can communicate with only one gateway (e.g. a smartphone, or a BLE hub) at a set time. When a peripheral goes out of range, it loses connectivity to a gateway, and cannot connect and seamlessly communicate with another gateway without user interventions. In other words, BLE connections do not get automatically migrated or handed-off to another gateway. In this paper, we propose a system which brings seamless connectivity to BLE-capable mobile IoT devices in an environment that consists of a network of gateways. Our framework ensures that unmodified, commercial off-the-shelf BLE devices seamlessly and securely connect to a nearby gateway without any user intervention.

Searchable Symmetric Encryption (SSE) when deployed in the cloud allows one to query encrypted data without the risk of data leakage. Despite the widespread interest, existing surveys do not examine in detail how SSE’s underlying structures are designed and how these result in the many properties of a SSE scheme. This is the gap we seek to address, as well as presenting recent state-of-the-art advances on SSE. Specifically, we present a general framework and believe the discussions may lead to insights for potential new designs. We draw a few observations. First, most schemes use index table, where optimal index size and sublinear search can be achieved using an inverted index. Straightforward updating can only be achieved using direct index, but search time would be linear. A recent trend is the combinations of index table, and tree, deployed for efficient updating and storage. Secondly, mechanisms from related fields such as Oblivious RAM (ORAM) have been integrated to reduce leakages. However, using these mechanisms to minimise leakages in schemes with richer functionalities (e.g., ranked, range) is relatively unexplored. Thirdly, a new approach (e.g., multiple servers) is required to mitigate new and emerging attacks on leakage. Lastly, we observe that a proposed index may not be practically efficient when implemented, where I/O access must be taken into consideration.

Real-time editing tools like Google Docs, Microsoft Office Online, or Etherpad have changed the way of collaboration. Many of these tools are based on Operational Transforms (OT), which guarantee that the views of different clients onto a document remain consistent over time. Usually, documents and operations are exposed to the server in plaintext – and thus to administrators, governments, and potentially cyber criminals. Therefore, it is highly desirable to work collaboratively on encrypted documents. Previous implementations do not unleash the full potential of this idea: They either require large storage, network, and computation overhead, are not real-time collaborative, or do not take the structure of the document into account. The latter simplifies the approach since only OT algorithms for byte sequences are required, but the resulting ciphertexts are almost four times the size of the corresponding plaintexts. We present SECRET, the first secure, efficient, and collaborative real-time editor. In contrast to all previous works, SECRET is the first tool that (1.) allows the encryption of whole documents or arbitrary sub-parts thereof, (2.) uses a novel combination of tree-based OT with a structure preserving encryption, and (3.) requires only a modern browser without any extra software installation or browser extension. We evaluate our implementation and show that its encryption overhead is three times smaller in comparison to all previous approaches. SECRET can even be used by multiple users in a low-bandwidth scenario. The source code of SECRET is published on GitHub as an open-source project:https://github.com/RUB-NDS/SECRET/

Modern vehicles may contain a considerable number of ECUs (Electronic Control Units) which are connected through various means of communication, with the CAN (Controller Area Network) protocol being the most widely used. However, several vulnerabilities such as the lack of authentication and the lack of data encryption have been pointed out by several authors, which ultimately render vehicles unsafe to their users and surroundings. Moreover, the lack of security in modern automobiles has been studied and analyzed by other researchers as well as several reports about modern car hacking have (already) been published. The contribution of this work aimed to analyze and test the level of security and how resilient is the CAN protocol by taking a BMW E90 (3-series) instrument cluster as a sample for a proof of concept study. This investigation was carried out by building and developing a rogue device using cheap commercially available components while being connected to the same CAN-Bus as a man in the middle device in order to send spoofed messages to the instrument cluster.

Online peer-to-peer platforms like Airbnb allow hosts to list a property (e.g. a house, or a room) for short-term rentals. In this work, we examine how hosts describe themselves on their Airbnb profile pages. We use a mixed-methods study to develop a categorization of the topics that hosts self-disclose in their profile descriptions, and show that these topics differ depending on the type of guest engagement expected. We also examine the perceived trustworthiness of profiles using topic-coded profiles from 1,200 hosts, showing that longer self-descriptions are perceived to be more trustworthy. Further, we show that there are common strategies (a mix of topics) hosts use in self-disclosure, and that these strategies cause differences in perceived trustworthiness scores. Finally, we show that the perceived trustworthiness score is a significant predictor of host choice–especially for shorter profiles that show more variation. The results are consistent with uncertainty reduction theory, reflect on the assertions of signaling theory, and have important design implications for sharing economy platforms, especially those facilitating online-to-offline social exchange.

In order to achieve a higher reusability and testability, static analyses are increasingly being build as modular pipelines of analysis components. However, to build, debug, test, and evaluate these components the complete pipeline has to be executed every time. This process recomputes intermediate results which have already been computed in a previous run but are lost because the preceding process ended and removed them from memory. We propose to leverage runtime reusability for static analysis pipelines and introduce SootKeeper, a framework to modularize static analyses into OSGi (Open Service Gateway initiative) bundles, which takes care of the automatic caching of intermediate results. Little to no change to the original analysis is necessary to use SootKeeper while speeding up the execution of code-build-debug cycles or evaluation pipelines significantly.

Internet of Things (loT) is network connected “Things” such as vehicles, buildings, embedded systems, sensors, as well as people. IoT enables these objects to collect and exchange data of interest to complete various tasks including patient health monitoring, environmental monitoring, system condition prognostics and prediction, smart grid, smart buildings, smart cities, and do on. Due to the large scale of and the limited host processor computation power in an IoT system, effective security provisioning is shifting from software-based security implementation to hardware-based security implementation in terms of efficiency and effectiveness. Moreover, FPGA can take over the work of infrastructure components to preserve and protect critical components and minimize the negative impacts on these components. In this paper, we employ Xilinx Zynq-7000 Series System-on-Chip (SoC) ZC706 prototype board to design an IoT device. To defend against threats to FPGA design, we have studied Zynq-ZC706 to (1) encrypt FPGA bitstream to protect the IoT device from bitstream decoding; (2) encrypt system boot image to enhance system security; and (3) ensure the FPGA operates correctly as intended via authentication to avoid spoofing and Trojan Horse attacks.

Cascading outages in power networks cause blackouts which lead to huge economic and social consequences. The traditional form of load shedding is avoidable in many cases by identifying optimal load control actions. However, if there is a change in the system topology (adding or removing loads, lines etc), the calculations have to be performed again. This paper addresses this problem by providing a workflow that 1) generates system models from IEEE CDF specifications, 2) identifies a collection of blackout causing contingencies, 3) dynamically sets up an optimization problem, and 4) generates a table of mitigation strategies in terms of minimal load curtailment. We demonstrate the applicability of our proposed methodology by finding load curtailment actions for N-k contingencies (k = 1, 2, 3) in IEEE 14 Bus system.

The Internet of Things (IoT) creates value by connecting digital processes to the physical world using embedded sensors, actuators and wireless networks. The IoT is increasingly intertwined with critical industrial processes, yet contemporary IoT devices offer limited security features, creating a large new attack surface and inhibiting the adoption of IoT technologies. Hardware security modules address this problem, however, their use increases the cost of embedded IoT devices. Furthermore, millions of IoT devices are already deployed without hardware security support. This paper addresses this problem by introducing a Security MicroVisor (SμV) middleware, which provides memory isolation and custom security operations using software virtualisation and assembly-level code verification. We showcase SμV by implementing a key security feature: remote attestation. Evaluation shows extremely low overhead in terms of memory, performance and battery lifetime for a representative IoT device.

Fast IPv4 scanning has enabled researchers to answer a wealth of new security and measurement questions. However, while increased network speeds and computational power have enabled comprehensive scans of the IPv4 address space, a brute-force approach does not scale to IPv6. Systems are limited to scanning a small fraction of the IPv6 address space and require an algorithmic approach to determine a small set of candidate addresses to probe. In this paper, we first explore the considerations that guide designing such algorithms. We introduce a new approach that identifies dense address space regions from a set of known "seed" addresses and generates a set of candidates to scan. We compare our algorithm 6Gen against Entropy/IP—the current state of the art—finding that we can recover between 1–8 times as many addresses for the five candidate datasets considered in the prior work. However, during our analysis, we uncover widespread IP aliasing in IPv6 networks. We discuss its effect on target generation and explore preliminary approaches for detecting aliased regions.

Every 98 seconds an American is sexually assaulted. Our work explores the use of on-body sensors to detect, communicate and prevent sexual assault. We present a stick-on clothing sensor which responds to initial signs of sexual assault such as disrobing to deter sexual abuse. The smart clothing operates in two modes: an active mode for instances when the victim is unconscious, and a passive mode where the victim can self-actuate the safety mechanism. Both modes alert the victim's friends and family, actuate an auditory alarm, activate odor-emitting capsules to create an immediate repulsion effect, and call emergency services. Our design is based on input from sexual assault survivors and college students who evaluated the clothing for aesthetic appeal, functionality, cultural sensitivity and their sense of personal safety. We show the practicality of our unobtrusive design with two user studies to demonstrate that our techno-social approach can help improve user safety and prevent sexual assault.

One of the main concerns of Cloud storage solutions is to offer the availability to the end user. Thus, addressing the mobility needs and device's variety has emerged as a major challenge. At first, data should be synchronized automatically and continuously when the user moves from one equipment to another. Secondly, the Cloud service should offer to the owner the possibility to share data with specific users. The paper's goal is to develop a secure framework that ensures file synchronization with high quality and minimal resource consumption. As a first step towards this goal, we propose the SyncDS protocol with its associated architecture. The synchronization protocol efficiency raises through the choice of the used networking protocol as well as the strategy of changes detection between two versions of file systems located in different devices. Our experiment results show that adopting the Hierarchical Hash Tree to detect the changes between two file systems and adopting the WebSocket protocol for the data exchanges improve the efficiency of the synchronization protocol.

Recent years have seen a trend towards decentralisation - from initiatives on decentralized web to decentralized network infrastructures. In this position paper, we present an architectural vision for decentralising cloud service infrastructures. Our vision is on community cloud infrastructures on top of decentralised access infrastructures i.e. community networks, using resources pooled from the community. Our architectural vision considers some fundamental challenges of integrating the current state of the art virtualisation technologies such as Software Defined Networking (SDN) into community infrastructures which are highly unreliable. Our proposed design goal is to include lightweight network and processing virtualization with fault tolerance mechanisms to ensure sufficient level of reliability to support local services.

A program exhibits trigger-based behavior if it performs undocumented, often malicious, functions when the environmental conditions and/or specific input values match some pre-specified criteria. Checking whether such hidden functions exist in the program is important for increasing trustworthiness of software. In this paper, we propose a framework to effectively detect trigger-based behavior at the source code level. Our approach is semi-automated: We use automated source code instrumentation and mixed concrete and symbolic execution to generate potentially suspicious test cases that may trigger hidden, potentially malicious functions. The test cases must be investigated by a human analyst manually to decide which of them are real triggers. While our approach is not fully automated, it greatly reduces manual work by allowing analysts to focus on a few test cases found by our automated tools.

With the increasing popularity of virtual currencies, it has become more important to have highly secure devices in which to store private-key information. Furthermore, ARM has made available an extension of processors architectures, designated TrustZone, which allows for the separation of trusted and non-trusted environments, while ensuring the integrity of the OS code. In this paper, we propose the exploitation of this technology to implement a flexible and reliable bitcoin wallet that is more resilient to dictionary and side-channel attacks. Making use of the TrustZone comes with the downside that writing and reading operations become slower, due to the encrypted storage, but we show that cryptographic operations can in fact be executed more efficiently as a result of platform-specific optimizations.

Logic locking is an intellectual property (IP) protection technique that prevents IP piracy, reverse engineering and overbuilding attacks by the untrusted foundry or endusers. Existing logic locking techniques are all vulnerable to various attacks, such as sensitization, key-pruning and signal skew analysis enabled removal attacks. In this paper, we propose TTLock that provably withstands all known attacks. TTLock protects a designer-specified number of input patterns, enabling a controlled and provably-secure trade-off between key-pruning attack resilience and removal attack resilience. All the key-bits converge on a single signal, creating maximal interference and thus resisting sensitization attacks. And, obfuscation is performed by modifying the design IP in a secret and traceless way, thwarting signal skew analysis and the removal attack it enables. Experimental results confirm our theoretical expectations that the computational complexity of attacks launched on TTLock grows exponentially with increasing key-size, while the area, power, and delay overhead increases only linearly.

Mature push button tools have emerged for checking trace properties (e.g. secrecy or authentication) of security protocols. The case of indistinguishability-based privacy properties (e.g. ballot privacy or anonymity) is more complex and constitutes an active research topic with several recent propositions of techniques and tools. We explore a novel approach based on type systems and provide a (sound) type system for proving equivalence of protocols, for a bounded or an unbounded number of sessions. The resulting prototype implementation has been tested on various protocols of the literature. It provides a significant speed-up (by orders of magnitude) compared to tools for a bounded number of sessions and complements in terms of expressiveness other state-of-the-art tools, such as ProVerif and Tamarin: e.g., we show that our analysis technique is the first one to handle a faithful encoding of the Helios e-voting protocol in the context of an untrusted ballot box.

The security of almost any real-world distributed system today depends on the participants having some "reasonably accurate" sense of current real time. Indeed, to name one example, the very authenticity of practically any communication on the Internet today hinges on the ability of the parties to accurately detect revocation of certificates, or expiration of passwords or shared keys.,,However, as recent attacks show, the standard protocols for determining time are subvertible, resulting in wide-spread security loss. Worse yet, we do not have security notions for network time protocols that (a) can be rigorously asserted, and (b) rigorously guarantee security of applications that require a sense of real time.,,We propose such notions, within the universally composable (UC) security framework. That is, we formulate ideal functionalities that capture a number of prevalent forms of time measurement within existing systems. We show how they can be realized by real-world protocols, and how they can be used to assert security of time-reliant applications - specifically, certificates with revocation and expiration times. This allows for relatively clear and modular treatment of the use of time consensus in security-sensitive systems.,,Our modeling and analysis are done within the existing UC framework, in spite of its asynchronous, event-driven nature. This allows incorporating the use of real time within the existing body of analytical work done in this framework. In particular it allows for rigorous incorporation of real time within cryptographic tools and primitives.