Biblio

Non-malleability is an important and intensively studied security notion for many cryptographic primitives. In the context of public key encryption, this notion means it is infeasible for an adversary to transform an encryption of some message m into one of a related message m' under the given public key. Although it has provided a strong security property for many applications, it still does not suffice for some scenarios like the system where the users could issue keys on-the-fly. In such settings, the adversary may have the power to transform the given public key and the ciphertext. To withstand such attacks, Fischlin introduced a stronger notion, known as complete non-malleability, which requires that the non-malleability property be preserved even for the adversaries attempting to produce a ciphertext of some related message under the transformed public key. To date, many schemes satisfying this stronger security have been proposed, but they are either inefficient or proved secure in the random oracle model. In this work, we put forward a new encryption scheme in the common reference string model. Based on the standard DBDH assumption, the proposed scheme is proved completely non-malleable secure against adaptive chosen ciphertext attacks in the standard model. In our scheme, the well-formed public keys and ciphertexts could be publicly recognized without drawing support from unwieldy techniques like non-interactive zero knowledge proofs or one-time signatures, thus achieving a better performance.

Machine learning is widely used in security-sensitive settings like spam and malware detection, although it has been shown that malicious data can be carefully modified at test time to evade detection. To overcome this limitation, adversary-aware learning algorithms have been developed, exploiting robust optimization and game-theoretical models to incorporate knowledge of potential adversarial data manipulations into the learning algorithm. Despite these techniques have been shown to be effective in some adversarial learning tasks, their adoption in practice is hindered by different factors, including the difficulty of meeting specific theoretical requirements, the complexity of implementation, and scalability issues, in terms of computational time and space required during training. In this work, we aim to develop secure kernel machines against evasion attacks that are not computationally more demanding than their non-secure counterparts. In particular, leveraging recent work on robustness and regularization, we show that the security of a linear classifier can be drastically improved by selecting a proper regularizer, depending on the kind of evasion attack, as well as unbalancing the cost of classification errors. We then discuss the security of nonlinear kernel machines, and show that a proper choice of the kernel function is crucial. We also show that unbalancing the cost of classification errors and varying some kernel parameters can further improve classifier security, yielding decision functions that better enclose the legitimate data. Our results on spam and PDF malware detection corroborate our analysis.

Consider a synchronous distributed network which is partly controlled by an adversary. In a Perfectly Secret Message Transmission(PSMT) protocol, the sender S wishes to transmit a message to the receiver R such that the adversary learns nothing about the message. We characterize the set of directed graphs that admit PSMT protocols tolerating a dual failure model where up to tp nodes are passively corrupted and further up to any tf nodes may fail.

The secure two-party computation (S2PC) protocols SHADE and GSHADE have been introduced by Bringer et al. in the last two years. The protocol GSHADE permits to compute different distances (Hamming, Euclidean, Mahalanobis) quite efficiently and is one of the most efficient compared to other S2PC methods. Thus this protocol can be used to efficiently compute one-to-many identification for several biometrics data (iris, face, fingerprint). In this paper, we introduce two extensions of GSHADE. The first one enables us to evaluate new multiplicative functions. This way, we show how to apply GSHADE to a classical machine learning algorithm. The second one is a new proposal to secure GSHADE against malicious adversaries following the recent dual execution and cut-and-choose strategies. The additional cost is very small. By preserving the GSHADE's structure, our extensions are very efficient compared to other S2PC methods.

We study coding schemes for multiparty interactive communication over synchronous networks that suffer from stochastic noise, where each bit is independently flipped with probability ε. We analyze the minimal overhead that must be added by the coding scheme in order to succeed in performing the computation despite the noise. Our main result is a lower bound on the communication of any noise-resilient protocol over a synchronous star network with n-parties (where all parties communicate in every round). Specifically, we show a task that can be solved by communicating T bits over the noise-free network, but for which any protocol with success probability of 1-o(1) must communicate at least Ω(T log n / log log n) bits when the channels are noisy. By a 1994 result of Rajagopalan and Schulman, the slowdown we prove is the highest one can obtain on any topology, up to a log log n factor. We complete our lower bound with a matching coding scheme that achieves the same overhead; thus, the capacity of (synchronous) star networks is Θ(log log n / log n). Our bounds prove that, despite several previous coding schemes with rate Ω(1) for certain topologies, no coding scheme with constant rate Ω(1) exists for arbitrary n-party noisy networks.

Randomness extractors and error correcting codes are fundamental objects in computer science. Recently, there have been several natural generalizations of these objects, in the context and study of tamper resilient cryptography. These are seeded non-malleable extractors, introduced by Dodis and Wichs; seedless non-malleable extractors, introduced by Cheraghchi and Guruswami; and non-malleable codes, introduced by Dziembowski, Pietrzak and Wichs. Besides being interesting on their own, they also have important applications in cryptography, e.g, privacy amplification with an active adversary, explicit non-malleable codes etc, and often have unexpected connections to their non-tampered analogues. However, the known constructions are far behind their non-tampered counterparts. Indeed, the best known seeded non-malleable extractor requires min-entropy rate at least 0.49; while explicit constructions of non-malleable two-source extractors were not known even if both sources have full min-entropy, and was left as an open problem by Cheraghchi and Guruswami. In this paper we make progress towards solving the above problems and other related generalizations. Our contributions are as follows. (1) We construct an explicit seeded non-malleable extractor for polylogarithmic min-entropy. This dramatically improves all previous results and gives a simpler 2-round privacy amplification protocol with optimal entropy loss, matching the best known result. In fact, we construct more general seeded non-malleable extractors (that can handle multiple adversaries) which were used in the recent construction of explicit two-source extractors for polylogarithmic min-entropy. (2) We construct the first explicit non-malleable two-source extractor for almost full min-entropy thus resolving the open question posed by Cheraghchi and Guruswami. (3) We motivate and initiate the study of two natural generalizations of seedless non-malleable extractors and non-malleable codes, where the sources or the codeword may be tampered many times. By using the connection found by Cheraghchi and Guruswami and providing efficient sampling algorithms, we obtain the first explicit non-malleable codes with tampering degree t, with near optimal rate and error. We call these stronger notions one-many and many-manynon-malleable codes. This provides a stronger information theoretic analogue of a primitive known as continuous non-malleable codes. Our basic technique used in all of our constructions can be seen as inspired, in part, by the techniques previously used to construct cryptographic non-malleable commitments.

Suppose that you have n truly random bits x=(x1,…,xn) and you wish to use them to generate m≫ n pseudorandom bits y=(y1,…, ym) using a local mapping, i.e., each yi should depend on at most d=O(1) bits of x. In the polynomial regime of m=ns, stextgreater1, the only known solution, originates from (Goldreich, ECCC 2000), is based on Random Local Functions: Compute yi by applying some fixed (public) d-ary predicate P to a random (public) tuple of distinct inputs (xi1,…,xid). Our goal in this paper is to understand, for any value of s, how the pseudorandomness of the resulting sequence depends on the choice of the underlying predicate. We derive the following results: (1) We show that pseudorandomness against F2-linear adversaries (i.e., the distribution y has low-bias) is achieved if the predicate is (a) k=Ω(s)-resilience, i.e., uncorrelated with any k-subset of its inputs, and (b) has algebraic degree of Ω(s) even after fixing Ω(s) of its inputs. We also show that these requirements are necessary, and so they form a tight characterization (up to constants) of security against linear attacks. Our positive result shows that a d-local low-bias generator can have output length of nΩ(d), answering an open question of Mossel, Shpilka and Trevisan (FOCS, 2003). Our negative result shows that a candidate for pseudorandom generator proposed by the first author (computational complexity, 2015) and by O’Donnell and Witmer (CCC 2014) is insecure. We use similar techniques to refute a conjecture of Feldman, Perkins and Vempala (STOC 2015) regarding the hardness of planted constraint satisfaction problems. (2) Motivated by the cryptanalysis literature, we consider security against algebraic attacks. We provide the first theoretical treatment of such attacks by formalizing a general notion of algebraic inversion and distinguishing attacks based on the Polynomial Calculus proof system. We show that algebraic attacks succeed if and only if there exist a degree e=O(s) non-zero polynomial Q whose roots cover the roots of P or cover the roots of P’s complement. As a corollary, we obtain the first example of a predicate P for which the generated sequence y passes all linear tests but fails to pass some polynomial-time computable test, answering an open question posed by the first author (Question 4.9, computational complexity 2015).

We present a task-based domain-decomposition preconditioner for partial differential equations (PDEs) resilient to silent data corruption (SDC) and hard faults. The algorithm exploits a reformulation of the PDE as a sampling problem, followed by a regression-based solution update that is resilient to SDC. We adopt a server-client model implemented using the User Level Fault Mitigation MPI (MPI-ULFM). All state information is held by the servers, while clients only serve as computational units. The task-based nature of the algorithm and the capabilities of ULFM are complemented at the algorithm level to support missing tasks, making the application resilient to hard faults affecting the clients. Weak and strong scaling tests up to \textasciitilde115k cores show an excellent performance of the application with efficiencies above 90%, demonstrating the suitability to run at large scale. We demonstrate the resilience of the application for a 2D elliptic PDE by injecting SDC using a random single bit-flip model, and hard faults in the form of clients crashing. We show that in all cases, the application converges to the right solution. We analyze the overhead caused by the faults, and show that, for the test problem considered, the overhead incurred due to SDC is minimal compared to that from the hard faults.

Web Service Architecture gives a compatible and scalable structure for web service interactions with performance, responsiveness, reliability and security to make a quality of software design. Systematic quantitative approaches have been discussed for designing and developing software systems that meet performance objectives. Many companies have successfully applied these techniques in different applications to achieve better performance in terms of financial, customer satisfaction, and other benefits. This paper describes the architecture, design, implementation, integration testing, performance and maintenance of new applications. The most successful best practices used in world class organizations are discussed. This will help the application, component, and software system designers to develop web applications and fine tune the existing methods in line with the best practices. In business process automation, many standard practices and technologies have been used to model and execute business processes. The emerging technology is web applications technology which provides a great flexibility for development of interoperable environment services. In this paper we propose a Case study of Automatic Gas Booking system, a business process development strategy and best practices used in development of software components used in web applications. The classification of QWS dataset with 2507 records, service invocations, integration and security for web applications have been discussed.

Defending computer networks from ongoing security incidents is a key requirement to ensure service continuity. Handling incidents in real-time is a complex process consisting of the three single steps: intrusion detection, alert processing and intrusion response. For useful and automated incident handling a comprehensive view on the process and tightly interleaved single steps are required. Existing solutions for incident handling merely focus on a single step leaving the other steps completely aside. Incompatible and encapsulated partial solutions are the consequence. This paper proposes an incident handling systems (IHS) based on a novel execution model that allows interleaving and collaborative interaction between the incident handling steps realized using the Blackboard Pattern. Our holistic information model lays the foundation for a conflict-free collaboration. The incident handling steps are further segmented into exchangeable functional blocks distributed across the network. To show the applicability of our approach, typical use cases for incident handling systems are identified and tested with our implementation.

The IoT will host a large number of co-existing cyber-physical applications. Continuous change, application interference, environment dynamics and uncertainty lead to complex effects which must be controlled to give performance and application guarantees. Application and platform self-configuration and self-awareness are one paradigm to approach this challenge. They can leverage context knowledge to control platform and application functions and their interaction. They could play a dominant role in large scale cyber-physical systems and systems-of-systems, simply because no person can oversee the whole system functionality and dynamics. IoT adds a new dimension because Internet based services will increasingly be used in such system functions. Autonomous vehicles accessing cloud services for efficiency and comfort as well as to reach the required level of safety and security are an example. Such vehicle platforms will communicate with a service infrastructure that must be reliable and highly responsive. Automated continuous self-configuration of data storage might be a good basis for such services up to the point where the different self-x strategies might affect each other, in a positive or negative form. This paper contains three contributions from different domains representing the current status of self-aware systems as they will meet in the Internet-of-Things and closes with a short discussion of upcoming challenges.

Physical unclonable functions (PUFs) utilize manufacturing ariations of circuit elements to produce unpredictable response to any challenge vector. The attack on PUF aims to predict the PUF response to all challenge vectors while only a small number of challenge-response pairs (CRPs) are known. The target PUFs in this paper include the Arbiter PUF (ArbPUF) and the Memristor Crossbar PUF (MXbarPUF). The manufacturing variations of the circuit elements in the targeted PUF can be characterized by a weight vector. An optimization-theoretic attack on the target PUFs is proposed. The feasible space for a PUF's weight vector is described by a convex polytope confined by the known CRPs. The centroid of the polytope is chosen as the estimate of the actual weight vector, while new CRPs are adaptively added into the original set of known CRPs. The linear behavior of both ArbPUF and MXbarPUF is proven which ensures that the feasible space for their weight vectors is convex. Simulation shows that our approach needs 71.4% fewer known CRPs and 86.5% less time than the state-of-the-art machine learning based approach.

Secure hardware design is a challenging task that goes far beyond ensuring functional correctness. Important design properties such as non-interference cannot be verified on functional circuit models due to the lack of essential information (e.g., sensitivity level) for reasoning about security. Hardware information flow tracking (IFT) techniques associate data objects in the hardware design with sensitivity labels for modeling security-related behaviors. They allow the designer to test and verify security properties related to confidentiality, integrity, and logical side channels. However, precisely accounting for each bit of information flow at the hardware level can be expensive. In this work, we focus on the precision of the IFT logic. The key idea is to selectively introduce only one sided errors (false positives); these provide a conservative and safe information flow response while reducing the complexity of the security logic. We investigate the effect of logic synthesis on the quality and complexity of hardware IFT and reveal how different logic synthesis optimizations affect the amount of false positives and design overheads of IFT logic. We propose novel techniques to further simplify the IFT logic while adding no, or only a minimum number of, false positives. Additionally, we provide a solution to quantitatively introduce false positives in order to accelerate information flow security verification. Experimental results using IWLS benchmarks show that our method can reduce complexity of GLIFT by 14.47% while adding 0.20% of false positives on average. By quantitatively introducing false positives, we can achieve up to a 55.72% speedup in verification time.

A finite state machine (FSM) is responsible for controlling the overall functionality of most digital systems and, therefore, the security of the whole system can be compromised if there are vulnerabilities in the FSM. These vulnerabilities can be created by improper designs or by the synthesis tool which introduces additional don't-care states and transitions during the optimization and synthesis process. An attacker can utilize these vulnerabilities to perform fault injection attacks or insert malicious hardware modifications (Trojan) to gain unauthorized access to some specific states. To our knowledge, no systematic approaches have been proposed to analyze these vulnerabilities in FSM. In this paper, we develop a framework named Analyzing Vulnerabilities in FSM (AVFSM) which extracts the state transition graph (including the don't-care states and transitions) from a gate-level netlist using a novel Automatic Test Pattern Generation (ATPG) based approach and quantifies the vulnerabilities of the design to fault injection and hardware Trojan insertion. We demonstrate the applicability of the AVFSM framework by analyzing the vulnerabilities in the FSM of AES and RSA encryption module. We also propose a low-cost mitigation technique to make FSM more secure against these attacks.

Systematic implementation of System-on-Chip (SoC) security policies typically involves smart wrappers extracting local security critical events of interest from Intellectual Property (IP) blocks, together with a control engine that communicates with the wrappers to analyze the events for policy adherence. However, developing customized wrappers at each IP for security requirements may incur significant overhead in area and hardware resources. In this paper, we address this problem by exploiting the extensive design-for-debug (DfD) instrumentation already available on-chip. In addition to reduction in the overall hardware overhead, the approach also adds flexibility to the security architecture itself, e.g., permitting use of on-field DfD instrumentation, survivability and control hooks to patch security policy implementation in response to bugs and attacks found at post-silicon or changing security requirements on-field. We show how to design scalable interface between security and debug architectures that provides the benefits of flexibility to security policy implementation without interfering with existing debug and survivability use cases and at minimal additional cost in energy and design complexity.

Information-Centric Networking (ICN) is an emerging networking paradigm that focuses on content distribution and aims at replacing the current IP stack. Implementations of ICN have demonstrated its advantages over IP, in terms of network performance and resource requirements. Because of these advantages, ICN is also considered to be a good network paradigm candidate for the Internet-of-Things (IoT), especially in scenarios involving resource constrained devices. In this paper we propose OnboardICNg, the first secure protocol for on-boarding (authenticating and authorizing) IoT devices in ICN mesh networks. OnboardICNg can securely onboard resource constrained devices into an existing IoT network, outperforming the authentication protocol selected for the ZigBee-IP specification: EAP-PANA, i.e., the Protocol for carrying Authentication for Network Access (PANA) combined with the Extensible Authentication Protocol (EAP). In particular we show that, compared with EAP-PANA, OnboardICNg reduces the communication and energy consumption, by 87% and 66%, respectively.

Several technologies, such as WiFi, Ethernet and power-line communications (PLC), can be used to build residential and enterprise networks. These technologies often co-exist; most networks use WiFi, and buildings are readily equipped with electrical wires that can offer a capacity up to 1 Gbps with PLC. Yet, current networks do not exploit this rich diversity and often operate far below the available capacity. We design, implement, and evaluate EMPoWER, a system that exploits simultaneously several potentially-interfering mediums. It operates at layer 2.5, between the MAC and IP layers, and combines routing (to find multiple concurrent routes) and congestion control (to efficiently balance traffic across the routes). To optimize resource utilization and robustness, both components exploit the heterogeneous nature of the network. They are fair and efficient, and they operate only within the local area network, without affecting remote Internet hosts. We demonstrate the performance gains of EMPoWER, by simulations and experiments on a 22-node testbed. We show that PLC/WiFi, benefiting from the diversity offered by wireless and electrical mediums, provides significant throughput gains (up to 10x) and improves coverage, compared to multi-channel WiFi.

While the potential advantages of geographic forwarding in wireless sensor networks (WSN) have been demonstrated for a while now, research in applying Information Centric Networking (ICN) has only gained momentum in the last few years. In this paper, we bridge these two worlds by proposing an ICN-compliant and secure implementation of geographic forwarding for ICN. We implement as a proof of concept the Greedy Perimeter Stateless Routing (GPSR) algorithm and compare its performance to that of vanilla ICN forwarding. We also evaluate the cost of security in 802.15.4 networks in terms of energy, memory and CPU footprint. We show that in sparse but large networks, GPSR outperforms vanilla ICN forwarding in both memory footprint and CPU consumption. However, GPSR is more energy intensive because of the cost of communications.

Information Centric Networking (ICN) paradigms nicely fit the world of wireless sensors, whose devices have tight constraints. In this poster, we compare two alternative designs for secure association of new IoT devices in existing ICN deployments, which are based on asymmetric and symmetric cryptography respectively. While the security properties of both approaches are equivalent, an interesting trade-off arises between properties of the protocol vs properties of its implementation in current IoT boards. Indeed, while the asymmetric-keys based approach incurs a lower traffic overhead (of about 30%), we find that its implementation is significantly more energy- and time-consuming due to the cost of cryptographic operations (it requires up to 41x more energy and 8x more time).

We consider wireless networks in which the effects of interference are determined by the SINR model. We address the question of structuring distributed communication when stations have very limited individual capabilities. In particular, nodes do not know their geographic coordinates, neighborhoods or even the size n of the network, nor can they sense collisions. Each node is equipped only with its unique name from a range \1, ..., N\. We study the following three settings and distributed algorithms for communication problems in each of them. In the uncoordinated-start case, when one node starts an execution and other nodes are awoken by receiving messages from already awoken nodes, we present a randomized broadcast algorithm which wakes up all the nodes in O(n log2 N) rounds with high probability. In the synchronized-start case, when all the nodes simultaneously start an execution, we give a randomized algorithm that computes a backbone of the network in O(Δ log7 N) rounds with high probability. Finally, in the partly-coordinated-start case, when a number of nodes start an execution together and other nodes are awoken by receiving messages from the already awoken nodes, we develop an algorithm that creates a backbone network in time O(n log2 N + Δ log7 N) with high probability.

The necessity to deploy wireless mesh network is determined by the real world application requirements. WMN does not fit some application well due to latency issues and capacity related problem with paths having more than 2 hops. With the promising IEEE 802.11ac based device a better fairness for multi-hop communications are expected to support broadband application; the rate usually varies according to the link quality and network environment. Careful network planning can effectively improves the throughput and delay of the overall network. We provide model for the placement of router nodes as an optimization process to improve performance. Our aim is to propose a WMNs planning model based on multiobjective constraints like coverage, reliability, and cost of deployment. The bit rate guarantee therefore necessary to limit the number of stations connected to the access point; to takes into account delay and fairness of the network the user's behaviors are derived. We use a multiobjective evolutionary algorithm based metaheuristic to evaluate the performance of our proposed placement algorithm.

Nowadays Wireless Mesh Networks (WMNs) has come up with a promising solution for modern wireless communications. But, one of the major problems with WMN is the mobility of the Mesh Clients (MCs). To offer seamless connectivity to the MCs, their mobility management is necessary. During mobility management one of the major concerns is the communication overhead incurred during handoff of the MCs. For addressing this concern, many schemes have been proposed by the researchers. In this paper, a classification of the existing intra domain mobility management schemes has been presented. The schemes have been numerically analyzed. Finally, their performance has been analyzed and compared with respect to handoff cost considering different mobility rates of the MCs.

Real world wireless networks usually have diverse connectivity characteristics. Although existing works have identified replication as the key to the successful design of routing protocols for these networks, the questions of when the replication should be used, by how much, and how to distribute packet copies are still not satisfactorily answered. In this paper, we investigate the above questions and present the design of the Hybrid Routing Protocol (HRP). We make a key observation that delay correlations can significantly impact performance improvements gained from packet replication. Thus, we propose a novel model to capture the correlations of inter-contact times among a group of nodes. HRP utilizes both direct delays feedback and the proposed model to estimate the replication gain, which is then fed into a novel regret-minimization algorithm to dynamically decide the amount of packet replication under unknown network conditions. We evaluate HRP through extensive simulations. We show that HRP achieves up to 3.5x delivery ratio improvement and up to 50% delay reduction, with comparable and even lower overhead than state-of-art routing protocols.

Various mobile applications require different QoS requirements, thus there is a need to resolve the application requirement into the underlying mesh network to support them. Existing approach to coordinate the application traffic requirement to underlying network has been applied in wired domains. However, it is complex in the wireless domain due to the mobility and diversity of mobile applications. Much interest is focused on resolving application QoS and match request to mesh network link availability. We propose a testbed architecture which allows dynamic configuration of mesh networks and coordination of each flow to support application-aware QoS. Our prototype testbed shows adaptive change in mesh network routing configuration depending on application requests.

Cryptocurrencies record transactions in a decentralized data structure called a blockchain. Two of the most popular cryptocurrencies, Bitcoin and Ethereum, support the feature to encode rules or scripts for processing transactions. This feature has evolved to give practical shape to the ideas of smart contracts, or full-fledged programs that are run on blockchains. Recently, Ethereum's smart contract system has seen steady adoption, supporting tens of thousands of contracts, holding millions dollars worth of virtual coins. In this paper, we investigate the security of running smart contracts based on Ethereum in an open distributed network like those of cryptocurrencies. We introduce several new security problems in which an adversary can manipulate smart contract execution to gain profit. These bugs suggest subtle gaps in the understanding of the distributed semantics of the underlying platform. As a refinement, we propose ways to enhance the operational semantics of Ethereum to make contracts less vulnerable. For developers writing contracts for the existing Ethereum system, we build a symbolic execution tool called Oyente to find potential security bugs. Among 19, 336 existing Ethereum contracts, Oyente flags 8, 833 of them as vulnerable, including the TheDAO bug which led to a 60 million US dollar loss in June 2016. We also discuss the severity of other attacks for several case studies which have source code available and confirm the attacks (which target only our accounts) in the main Ethereum network.