As a big data analysis technique, hierarchical clustering is helpful in summarizing data since it returns the clusters of the data and their clustering history. Cloud computing is the most suitable option to efficiently perform hierarchical clustering over numerous data. However, since compromised cloud service providers can cause serious privacy problems by revealing data, it is necessary to solve the problems prior to using the external cloud service. Privacy-preserving hierarchical clustering protocol in an outsourced computing environment has never been proposed in existing works. Existing protocols have several problems that limit the number of participating data owners or disclose the information of data. In this paper, we propose a parallelly running and privacy-preserving agglomerative hierarchical clustering (ppAHC) over the union of datasets of multiple parties in an outsourced computing environment, which is the first protocol to the best of our knowledge. The proposed ppAHC does not disclose any information about input and output, including the data access patterns. The proposed ppAHC is highly efficient and suitable for big data analysis to handle numerous data since its cost for one round is independent of the amount of data. It allows data owners without sufficient computing capability to participate in a collaborative hierarchical clustering.

Recently, LiDARs have attracted a lot of attention because they enable Advanced Driver Assistance Systems (ADAS) by precisely measuring their surroundings. However, with this increased interest, adversarial attacks on LiDARs have also been demonstrated. Since LiDARs, by default, recognize the strongest reflected pulse among multiple returning pulses, these attacks exploit high-intensity laser pulses to remove original real points and create spoofed points in the point cloud. These spoofed points can serve as perturbations that cause detection errors in a object detection model using LiDAR data. To detect spoofed points, existing defense methods have only analyzed their locations in a point cloud (i.e., x, y, z). Although LiDARs provide the intensity of the reflected pulses, defense methods have ignored the intensity when detecting spoofed points. In this paper, we present a new method to detect spoofed points that are created by high-intensity laser pulse injection. Based on the fact that a higher intensity level is required to generate spoofed points in a point cloud, our method is designed to analyze the intensity of reflected pulses to identify injected pulses by attackers. Using the Adam optimization algorithm, our method resulted in a false positive rate of 3.88% for SECOND and 4.40% for PointPillar. The true positive rate was generally over 40% higher than that of other defense methods, and at least 10% higher in the worst-case scenario.

With the advancement of connected and automated vehicles (CAVs), drivers now have access to convenient features such as lane-keeping, cruise control, and more. The electronic control units (ECUs) equipped within vehicles communicate with each other through the controller area network (CAN). However, since the CAN does not possess any security mechanisms, it becomes a target for adversaries to attack. In light of this, a significant amount of research regarding intrusion detection systems (IDSs) has focused on detecting such maliciously injected CAN packets. Nevertheless, most existing machine learning-based IDSs neither calculate the exact time intervals of the CAN packets nor utilize the counter information. Precise timing intervals are a crucial feature for detecting spoofing, fuzzing, and replay attacks, and counter information is also a significant feature that can detect fuzzing and replay attacks. Therefore, in this paper, we propose a methodology for extracting two detection features that are aware of CAN frame characteristics: the interframe space (IFS) between two consecutive CAN packets, and the counter information of a CAN data payload (i.e., data field). Using these features, we introduce decision tree-based IDS. We evaluate the proposed features with popular decision tree-based models such as random forest and extreme gradient boosting (XGBoost). The results show that our proposed IDS can detect maliciously injected CAN packets with an F1 score of 99.54% in binary classification and 97.99% in multi-class classification, which are higher scores than what existing machine/deep learning-based IDSs achieve. Additionally, we measure the detection time of our proposed IDS in both online and offline testing environments.

Ultra-wideband (UWB) communication is an emerging technology that enables secure ranging and localization. Since UWB communication enables measuring an exact distance, enhanced security would be expected based on it. Recently, however, it has been demonstrated that a distance measured by IEEE 802.15.4z high-rate pulse repetition frequency (HRP) UWB ranging system can be maliciously reduced. The HRP UWB ranging system is widely adopted by smartphone manufacturers such as Samsung and Apple.

For autonomous driving systems, cameras and LiDAR sensors are necessary devices that provide precise depth information by which positions and sizes of objects can be identified. Moreover, recent advances in deep learning have extended their capabilities to include monocular camera setup for depth estimation. Compared with the conventional devices like LiDAR or stereo cameras for the depth estimation, the monocular camera enables to estimate depths with a low cost. It is known that the depth estimation models for the monocular camera are vulnerable to adversarial examples. However, most adversarial attacks against the monocular depth estimation have been conducted with targeted patches that are placed on a target object. It is known that the targeted patch outperforms the adjacent and remote patch that is placed beyond the target object, when it comes to an attack success rate. However, the adjacent and remote patch would provide high flexibility in patch placement, as it can be placed beyond the target object's scope. In this paper, we experimentally confirm that the patch placement significantly affects the attack success rates, particularly in specific regions.

There are many various data-oriented attacks on robotic vehicles (RVs) that change the inputs of an RV control program. While much research has been dedicated to detecting the attacks, the recovery mechanism has received relatively less attention. Without recovery after detection, an RV cannot continue with its assigned missions. Unfortunately, the existing recovery mechanisms have limitations that make it difficult to deploy these in real RVs, such that they require additional hardware/software or can only recover from the limited types of data-oriented attacks. To overcome these limitations, we propose a framework called SCVMON that detects and helps RVs recover from various data-oriented attacks that generate inappropriate control commands. Based on the observation that data-oriented attacks inevitably change the values of some variables in RV control programs, SCVMON systematically identifies the safety-critical variables (SCVs) that can affect the safety of RVs. For efficient recovery, we extract from SCVs a set of monitored safety-critical variables (mSCVs) that can reflect all input changes, and monitor them to detect and recover from various data-oriented attacks. SCVMON does not depend on the physical nature of a specific sensor or hardware, which is a significant benefit, and it can be applied through a simple software update. Our evaluation shows that SCVMON can quickly detect and recover from 20 types of data-oriented attacks. Also, SCVMON incurs only 0.3% storage overhead and up to 5.1% runtime overhead, proving that it is suitable for RVs.

These days, smartwatches are becoming more common and can even operate in stand-alone mode. This increases the need for smartwatches to authenticate users independently without paired smartphones. Currently, password or pattern-based methods can authenticate the smartwatch users in stand-alone mode, but these methods are known to be vulnerable to simple attacks such as shoulder-surfing and password dictionary attacks. In addition, biometric-based methods, which are expected to release on smartwatches in the near future, require inconvenient user interaction or special sensors for measurement. In light of this, we propose a smartwatch user authentication method that does not require any additional sensors or user interaction. Based on the fact that the human body structure affects the way vibrations are absorbed, reflected, and propagated, we designed a smartwatch user authentication method based on a challenge-response structure using vibrations. In our method, a challenge is a set of fresh random vibrations, which are provided by default in current smartwatches, and a response to the challenge is measured by built-in gyroscope and accelerometer sensors. Our earlier study demonstrated that commercial smartwatch users can be authenticated with a low equal error rate (EER) of 1.37 %. In this paper, we extended the analysis of our method on various vibration types by using a prototype setup. As a result, we discovered an outperformed vibration type for user authentication. We conducted further analysis for users with heavier body weights as these individuals are more vulnerable to a not-in-wear attack. Finally, we conducted more advanced impersonation attacks on test participants with one or more similar physical indicators to demonstrate that our method is also secure against a wider range of more complex attacks.

A device pretending to be behaving normally can carry out malicious acts that result in the leakage of sensitive information, invasion of privacy, damage property, or even loss of life. The first step to detect these malicious acts is to identify whether a device is authorized or not. There are existing methods for identifying devices based on cryptographic schemes or physical unclonable function (PUF), but each of these methods has disadvantages in that key management costs are incurred or additional chips or circuits are required. In this article, we propose a device identification method that overcomes these shortcomings. Based on the fact that MEMS sensors are built-in to most devices due to their various applications and the property that MEMS sensors are sensitive to acoustic signals with resonant frequencies, the proposed method uses MEMS sensor readings to acoustic signals. Many attack methods have been studied using this property to disable the normal function of the sensor or eavesdrop on speech around a device. On the other hand, our method is the first to fingerprint MEMS sensors using raw sensor readings to acoustic signals from a security point of view rather than from this conventional attack point of view. Furthermore, our method is based on a challenge-response structure to be secure from replay attacks; here, a challenge is a random acoustic signal, and a response is the unique MEMS sensor reading to the challenge. In our evaluation, we use commercial MEMS sensors and a low-cost speaker that costs less than$\$ $1. The results show that under various conditions that may affect MEMS sensor readings, the macro F1-scores when identifying authorized devices is 1.0, and the macro accuracy of detecting attacks using devices other than authorized ones is 0.994. As a result, our method can identify devices well at a low cost.

Contemporary vehicles have undergone numerous transformations to become fully computerized machines. This computerizing process is intended to provide safety and convenience for drivers; however, there have been many studies demonstrating how to remotely maneuver a vehicle by compromising its in-vehicle electronic control units (ECU). As a countermeasure, automotive intrusion detection systems (IDSs) have also been extensively explored as potential remedies. The clock-based IDS was one of the most promising methods for an automotive IDS, but researchers have recently determined it to be insufficient, as adversaries can emulate the clock skew. In this paper, we propose a novel automotive IDS that leverages the residuals—which have traditionally been considered an error that should be removed from analysis—of average and actual timestamp intervals of two consecutive controller area network (CAN) messages. Thus, we present a rationale as to why large residuals occur in a real in-vehicle CAN network. Our method analyzes transmission periodicity so closely that any minuscule change can be detected in the event of an intrusion. We show that our method detects a vehicle intrusion with a low false-alarm rate, and that it can detect a new sophisticated attack which emulates the clock skew of an original transmission. To the best of our knowledge, this is the first approach analyzing transmission time to detect the frequency masquerading attack with clock skew emulation. Finally, our method enables the sharing of parameters determined in a vehicle with other like models, which is meaningful for manufacturers in terms of scalability.

As autonomous driving technology continues to develop, communication for vehicles is becoming more important to provide an efficient and secure driving environment. Currently, vehicle-to-everything (V2X) based on fifth-generation (5G) is the only solution to meet the demanding requirements of self-driving cars in terms of ultra-low latency and ultra-high reliable connectivity under high mobility conditions, earning this technology more attention. Secure communication for vehicle-to-vehicle based on 5G (5G-V2V) is essential because vehicles decide how to maneuver and perceive situations based on the data exchanged. In this paper, we not only propose a new architecture for V2X based on 5G (5G-V2X) by utilizing network slicing (NS) to guarantee different features of V2X services but also analyze security requirements according to V2X service type. We also propose a secure V2V communication scheme based on 5G that satisfies these requirements. The security evaluation demonstrates that our scheme is secure against attacks on a V2V environment via both security proof and verification tool ProVerif. Through the performance evaluation, we prove that our scheme is more effective than the existing schemes while meeting end-to-end delay requirements for autonomous driving.

Smartwatches have come into wide use in recent years, and a number of smartwatch applications that improve convenience and user health are being developed and introduced constantly. Moreover, the latest smartwatches are now designed to operate without their paired smartphones, and as such, it is necessary for smartwatches to independently authenticate users. In these current devices, personal identification numbers (PIN) or patterns are entered to authenticate users, but these methods require inconvenient interaction for the user and are not highly secure. Particularly relevant to smartwatch technology, even user authentication based on biometric information needs either special sensors capable of measuring biometric information or user interaction. In this paper, we propose a usable method for user authentication on smartwatches without additional devices. Based on the fact that vibration is absorbed, reflected, and propagated differently according to the physical structure of each human body, our method is designed as a challenge-response scheme, in which the challenge is a random sequence of multiple vibration types that are already built into current smartwatches. The responses to vibrations are measured by the default gyroscope and accelerometer sensors in smartwatches. Moreover, our method is the first working model for commercial smartwatch models with low specifications when vibrating and measuring responses. We evaluated our method using a commercial smartwatch, and the results show that our method is able to authenticate a user with an equal error rate (EER) of 1.37%.

In theory, Control-Flow Integrity (CFI) is considered a principled solution against control-data attacks. However, most fine-grained CFI schemes that ensure such high security suffer from significant performance overhead. Existing practical implementations have been proposed to overcome this performance overhead problem, but they have proven unable to guarantee high security because development of these implementations has focused on only improving performance, at the expense of the security guarantee. Even though it is important for CFI schemes to provide both high security and low performance overhead, existing research on CFI is limited either by way of performance or security guarantee. We propose a new approach of verification method in fine-grained CFI to achieve these two goals. Our scheme performs selective and random verifications for certain branches rather than all branches, and thus, can reduce performance overhead. We show improved performance by evaluating our proof-of-concept implementation on SPEC CPU 2017. In addition, we also show that our scheme does not significantly sacrifice the security guarantee of fine-grained CFI by analyzing the structure of existing control-data attack exploits, which were collected from real-world exploits DB and related literature.

As a primitive function of location-based services (LBSs), the location sharing aims to provide a user's current location information to other designated users. In recent years, LBSs have become one of the most popular services provided by mobile online social networks (mOSNs). As LBSs actively exploit the users' identity and current location information, appropriate approaches have to be utilized to protect the location privacy of the users. Several recent reports have discussed the significance of friendship privacy protection with the goal of hiding the friendship relation of users from unintended entities. However, to the best of our knowledge, there hasn't been an approach for protecting the location sharing with complete privacy of location and friendship connections. To address this issue, we propose a new cryptographic primitive, functional pseudonym, for location sharing in mOSNs that ensures both of them. Unlike many of the existing solutions, our approach does not require a fully trusted server and does not assume pre-established secrets among friends, and therefore is highly practical. Also, the proposed approach significantly reduces computational overhead of users by delegating part of the computations for location sharing to a server, therefore it is highly sustainable. Our primitive can be widely used in many mOSNs to enable LBSs with improved privacy and sustainability. Consequently, it will contribute to proliferate LBSs by eliminating users privacy concerns.

A number of logs are generated from IT devices. Since logs have important information regarding a system, they are used for finding the trace of an intrusion or obtaining important information through a big data analysis. Hence, the logs have become a major attack surface for attackers. To protect logs, IT devices require secure logging methods as a mandatory service. Secure logging can provide detection of malicious manipulation of logs and verification of their origin. In this paper, we propose a secure logging method satisfying forward and backward secrecy based on ARM TrustZone for embedded systems, which enables to efficiently generate secure logs through inter-process communication without modification of the existing system (Syslog). Also, we show that the proposed method does not require extra overhead compared with the existing logging method.

Self-updatable encryption (SUE) is a new kind of public-key encryption, motivated by cloud computing, which enables anyone (i.e. cloud server with no access to private keys) to update a past ciphertext to a future ciphertext by using a public key. The main applications of SUE are revocable-storage attribute-based encryption (RS-ABE) that provides an efficient and secure access control to encrypted data stored in cloud storage. In this setting, there is a new threat such that a revoked user still can access past ciphertexts given to him by a storage server. RS-ABE solves this problem by combining user revocation and ciphertext updating functionalities. We propose the first SUE and RS-ABE schemes secure against a relevant form of chosen-ciphertext security (CCA). Due to the fact that some ciphertexts are easily derived from others, we employ a different notion of CCA that avoids easy challenge related messages. Specifically, we define “time extended challenge” CCA security for SUE which excludes ciphertexts that are easily derived from the challenge (over time periods) from being queried on. We then propose an efficient SUE scheme with such CCA security, and we also present an RS-ABE scheme with this CCA security.

The convergence of automobiles and ICT (information and communication technology) has become a new paradigm for the development of next-generation vehicles. In particular, connected cars represent the most in-demand automobile-ICT convergence technology. With the development of 5G technology, communication between vehicle and external device using autonomous driving and Internet of things (IoT) technology has been remarkably developed. Control of vehicles using smart phones has become a routine feature, and over 200 Android apps are in use. However, Android apps are easy to tamper by repackaging and allowing hackers to attack vehicles with using this vulnerability, which can lead to life-critical accidents. In this study, we analyze the vulnerabilities of connected car environments when connecting with IoT technologies and demonstrate the possibility of cyberattack by performing attack experiments using real cars and repackaging for commercial apps. Furthermore, we propose a realistic security technology as a countermeasure to attain safety against cyberattacks. To evaluate the safety of the proposed method, a security module is developed and a performance evaluation is conducted on an actual vehicle.

Implantable medical devices (IMDs) continuously monitor the condition of a patient and directly apply treatments if considered necessary. Because IMDs are highly effective for patients who frequently visit hospitals (e.g., because of chronic illnesses such as diabetes and heart disease), their use is increasing significantly. However, related security concerns have also come to the fore. It has been demonstrated that IMDs can be hacked—the IMD power can be turned off remotely, and abnormally large doses of drugs can be injected into the body. Thus, IMDs may ultimately threaten a patient’s life. In this paper, we propose an energy-aware key exchange protocol for securing IMDs. We utilize synchronous interpulse intervals (IPIs) as the source of a secret key. These IPIs enable IMDs to agree upon a secret key with an external programmer in an authenticated and transparent manner without any key material being exposed either before distribution or during initialization. We demonstrate that it is difficult for adversaries to guess the keys established using our method. In addition, we show that the reduced communication overhead of our method enhances battery life, making the proposed approach more energy-efficient than previous methods.

Biometric data is user-identifiable and therefore methods to use biometrics for authentication have been widely researched. Biometric cryptosystems allow for a user to derive a cryptographic key from noisy biometric data and perform a cryptographic task for authentication or encryption. The fuzzy extractor is known as a prominent biometric cryptosystem. However, the fuzzy extractor has a drawback in that a user is required to store user-specific helper data or receive it online from the server with additional trusted channel, to derive a correct key. In this paper, we present a new biometric-based key derivation function (BB-KDF) to address the issues. In our BB-KDF, users are able to derive cryptographic keys solely from their own biometric data: users do not need any other user-specific helper information. We introduce a security model for the BB-KDF. We then construct the BB-KDF and prove its security in our security model. We then propose an authentication protocol based on the BB-KDF. Finally, we give experimental results to analyze the performance of the BB-KDF. We show that our proposed BB-KDF is computationally efficient and can be deployed on many different kinds of devices.

Summary The main goal of code obfuscation is to make software more difficult to reverse engineer. These techniques modify data structures and control flow while retaining the functionality of the original program. Although obfuscation is a useful method for protecting programs, it can also be used to protect malware. This raises concerns that malware could use code obfuscation to avoid detection by antivirus software. It is very difficult to analyze the functionality of obfuscated malware before it has been deobfuscated. Furthermore, commercial obfuscation tools allow malware authors to apply multiple obfuscation options simultaneously, and current deobfuscation techniques cannot handle this situation. In this study, we analyzed a well‐known commercial obfuscation tool called Themida. We applied its many obfuscation options to a program and implemented a tool to recover the original code and data. We extracted features from obfuscated programs and analyzed their control flow. Our tool is based on these features and the control flow patterns and can identify whether Themida has been applied to the program and which obfuscation options have been used. Finally, we suggested a method for recovering the import address table of programs by using dynamic binary instrumentation. The proposed rules and algorithms can almost completely recover the APIs of programs even though they are hidden by obfuscation options provided by Themida.

The proliferation of computerized functions aimed at enhancing drivers' safety and convenience has increased the number of vehicular attack surfaces accordingly. The fundamental vulnerability is caused by the fact that the controller area network protocol, a de facto standard for in-vehicle networks, does not support message origin authentication. Several methods to resolve this problem have been suggested. However, most of them require modification of the CAN protocol and have their own vulnerabilities. In this paper, we focus on securing in-vehicle CAN networks, proposing a novel automotive intrusion detection system (so-called VoltageIDS). The system leverages the inimitable characteristics of an electrical CAN signal as a fingerprint of the electronic control units. The noteworthy contributions are that VoltageIDS does not require any modification of the current system and has been validated on actual vehicles while driving on the road. VoltageIDS is also the first automotive intrusion detection system capable of distinguishing between errors and the bus-off attack. Our experimental results on a CAN bus prototype and on real vehicles show that VoltageIDS detects intrusions in the in-vehicle CAN network. Moreover, we evaluate VoltageIDS while a vehicle is moving.

Vehicular ad-hoc networks (VANETs) have been researched with regard to enhance driver's safety and comfort. In VANETs, all vehicles share their status and road conditions with neighboring nodes by periodically generating safety messages. To provide reliable VANET services, message authentication is an important feature. In particular, anonymous message authentication has attracted considerable interest, because periodic broadcast messages from a vehicle can be used to track its location. Unfortunately, previously proposed anonymous message authentication protocols had serious practical shortcomings, including high communication, authentication, and revocation costs, as well as reliability issues. Thus, in this paper, we propose an anonymous authentication protocol based on a cooperative authentication method. The proposed method does not require mode synchronization between cooperative and non-cooperative authentication. In addition, we design a two-layer pseudo-identity generation method and construct a key update tree for efficient revocation. Simulations show that our protocol does not result in packet losses caused by authentication overheads, even when the vehicle density is 200/km2.

Abstract Threshold public‐key encryption can control decryption abilities of an authorized user group in such a way that each user of the group can produce only a decryption share and at least t of them should collect decryption shares to recover a message. We present a new threshold public‐key encryption that is secure against selectively chosen ciphertext attacks. Semantic security against chosen ciphertext adversaries is the de facto level of security for public‐key encryption deployed in practice because many encryption systems are broken in a model of chosen ciphertext security. The security of the proposed system is formally proved without random oracles under a new assumption. We also provide proof of the intractability of our assumption in the generic group model. Copyright © 2012 John Wiley & Sons, Ltd.

Abstract The availability of the Web service has been exposed to several threats such as distributed denial‐of‐service attack, which is not an unfamiliar terminology anymore. Sustaining availability against various attacks becomes the critical issue for high‐profile Web sites. In this paper, we propose a novel architecture providing Web service among client, called client cloud Web service, by utilizing resources of clients to enhance the availability. Client cloud Web service can be easily integrated into the current Internet protocol suite by providing a transparent layer in the middle of Hypertext Transfer Protocol layer and Transmission Control Protocol/Internet Protocol layer. It is shown by simulations that the proposed architecture can efficiently reduce the traffic when both the size of Web items and the number of requests from clients increase. Copyright © 2012 John Wiley & Sons, Ltd.

The controller area network with flexible data rate (CAN-FD) is attracting attention as the next generation of in-vehicle network technology. However, security issues have not been completely taken into account when designing CAN-FD, although every bit of information transmitted could be critical to driver safety. If we fail to solve the security vulnerabilities of CAN-FD, we cannot expect Vehicle-Information and Communications Technology (Vehicle-ICT) convergence to continue to develop. Fortunately, secure in-vehicle CAN-FD communication environments can be constructed using the larger data payload of CAN-FD. In this paper, we propose a security architecture for in-vehicle CAN-FD as a countermeasure (designed in accordance with CAN-FD specifications). We considered the characteristics of the International Organization for Standardization (ISO) 26262 Automotive Safety Integrity Level and the in-vehicle subnetwork to design a practical security architecture. We also evaluated the feasibility of the proposed security architecture using three kinds of microcontroller unit and the CANoe software. Our evaluation findings may be used as an indicator of the performance level of electronic control units for manufacturing next-generation vehicles.

In this study, the authors present an efficient public‐key broadcast encryption (PKBE) scheme with sub‐linear size of public keys, private keys and ciphertexts and prove its adaptive security under standard assumptions. Compared with the currently best scheme of Garg et al . (CCS 2010) that provides adaptive security under standard assumptions and sub‐linear size of various parameters, the ciphertext size of the author's scheme is 94% shorter and the encryption algorithm of their scheme is also 2.8 times faster than the scheme of Garg et al . To achieve their scheme, they adapt the dual system encryption technique of Waters. However, there is a challenging problem to use this technique for the construction of PKBE with sub‐linear size of ciphertexts such as a tag compression problem. To overcome this problem, they first devise a novel tag update technique for broadcast encryption. Using this technique, they build an efficient PKBE scheme in symmetric bilinear groups, and prove its adaptive security under standard assumptions.

A revocable identity-based encryption (RIBE) provides an efficient revocation method in IBE that a trusted authority periodically broadcasts an update key for nonrevoked users and a user can decrypt a ciphertext if he is not revoked in the update key. Boldyreva, Goyal, and Kumar (CCS 2008) defined RIBE and proposed an RIBE scheme that uses a tree-based revocation encryption scheme to revoke users' private keys. In this paper, we devise a new technique for RIBE and propose RIBE schemes with a constant number of private key elements. We achieve the following results. We first devise a new technique for RIBE that combines a hierarchical IBE (HIBE) scheme and a public-key broadcast encryption (PKBE) scheme using multilinear maps. In contrast to the previous technique for RIBE, our technique uses a PKBE scheme in bilinear maps for revocation to achieve short private keys and update keys. Following our new technique for RIBE, we propose an RIBE scheme in three-leveled multilinear maps that combines the HIBE scheme of Boneh and Boyen (EUROCRYPT 2004) and the PKBE scheme of Boneh, Gentry, and Waters (CRYPTO 2005). The private key and update key of our scheme possess a constant number of group elements. Next, we propose another RIBE scheme with reduced public parameters and short keys by combining the HIBE scheme of Boneh and Boyen and the PKBE scheme of Boneh, Waters, and Zhandry (CRYPTO 2014), which uses multilinear maps. Compared with our first RIBE scheme, our second RIBE scheme requires high-leveled multilinear maps.

Vehicle-IT convergence technology is a rapidly rising paradigm of modern vehicles, in which an electronic control unit (ECU) is used to control the vehicle electrical systems, and the controller area network (CAN), an in-vehicle network, is commonly used to construct an efficient network of ECUs. Unfortunately, security issues have not been treated properly in CAN, although CAN control messages could be life-critical. With the appearance of the connected car environment, in-vehicle networks (e.g., CAN) are now connected to external networks (e.g., 3G/4G mobile networks), enabling an adversary to perform a long-range wireless attack using CAN vulnerabilities. In this paper we show that a long-range wireless attack is physically possible using a real vehicle and malicious smartphone application in a connected car environment. We also propose a security protocol for CAN as a countermeasure designed in accordance with current CAN specifications. We evaluate the feasibility of the proposed security protocol using CANoe software and a DSP-F28335 microcontroller. Our results show that the proposed security protocol is more efficient than existing security protocols with respect to authentication delay and communication load.

The forthcoming internet of things - an intelligent collaboration of resource-limited devices such as wireless sensor nodes that are embedded in the daily lives of users - poses new challenges to security and end-user privacy. One of the most challenging problems is the thwarting of replica attacks. Once a sensor node is physically captured, it can be reprogrammed and replicated into a large number of replicas, which may maliciously occupy the network. Thus far, various schemes have been proposed to detect replicas; however, most of them require expensive hardware such as a global positioning system. In general, the ideal price for a sensor node is as low as one dollar, and thus, it is equipped with limited resources; hence, it is not practical to employ additional devices. In this paper, we propose a low-priced and efficient solution for replica detection in static wireless sensor networks. Although the proposed solution does not need any additional hardware, it exhibits similar or better performance, as compared to existing schemes. Through simulation experiments, we show that the proposed solution provides comparable performance in terms of the replica detection ratio and the time required to detect replicas. Furthermore, we show that the proposed solution saves more energy than existing schemes in most of our simulations.

Secure authentication in roaming services is being designed to allow legal users to get access to wireless network services when they are away from their home location. Recently, to protect the location privacy of users, there have been researches on anonymous authentication. In particular, anonymous authentication without the participation of home servers has attracted considerable interest owing to its influence on the communication efficiency. Unfortunately, the previously proposed anonymous authentication schemes have serious practical shortcomings, such as high communication and computation costs and huge revocation lists. In this paper, we propose a novel three-round anonymous roaming protocol that does not require the participation of home servers. The proposed protocol uses a pseudo-identity-based signcryption scheme to perform efficient revocation with a short revocation list and efficient authentication. The use of a signcryption algorithm minimizes the number of pseudo-identities stored in a Subscriber Identification Module (SIM) card with limited storage capacity. The authentication efficiency is also higher than that of existing protocols. The proposed protocol is formally proved in the Canetti-Krawczyk (CK) model.

The forthcoming Internet of Things – an intelligent collaboration of resource‐limited static/mobile devices that are embedded in the daily lives of users – poses new challenges to security and end‐user privacy. One of the most challenging problems is how to thwart replica attacks. Once a device is captured physically by an attacker or contaminated by malicious code, it can be reprogrammed and the secret information inside can be duplicated into a large number of replicas that maliciously occupy the network and collect users private information without authorisation. In this study, the authors focus on studying the detection of replicas in mobile applications; which can consist of resource‐limited static devices attached to mobile entities. Most existing solutions for detecting replicas have been designed for static devices, and cannot be immediately applied to mobile devices because of their unique properties, in particular, their node mobility. The authors present two efficient methods for detecting replicas in mobile devices. Through performance evaluations, they find that the proposed methods provide highly accurate replica detection with nearly zero detection errors. Furthermore, the distributed and cooperative strategy of the methods significantly reduces the energy required to detect replicas while providing faster replica detection than the existing solutions.

We present an anonymous hierarchical identity based encryption (HIBE) scheme that not only achieves constant-size ciphertext, but also works in bilinear groups with prime order. In contrast to our work, all previous anonymous HIBE schemes either have ciphertext size linear in the depth of the hierarchy or work in bilinear groups with a composite order. Our construction is more efficient than previous schemes in terms of ciphertext size and decryption cost. We give provable security of our construction, consisting of confidentiality and anonymity, without random oracles. To gain anonymity, we introduce a novel and simple method called “double exponent” technique, which gives an anonymous HIBE scheme more compact than the result at CRYPTO 2006. Our method is quite general in that it works on both symmetric and asymmetric bilinear maps. The simple method might also be of independent interest to gain anonymity of attributes in constructing searchable encryption schemes on encrypted data.

Hospitals have to use a large amount of medical data from individuals while protecting their privacy to execute medical data mining. It is important to find ‘rare’ cases among medical data of individuals in many healthcare applications. Therefore hospitals need privacy-preserving mining techniques to find rare cases among medical data of individuals. However, previous privacy-preserving data-mining techniques cannot be used to find rare cases. In this study, they suggest a privacy-preserving ‘range set union’ protocol that can be used to find rare cases in the private medical datasets of individuals.

In current computing environments, collaborative computing has been a central concern in Ubiquitous, Convergent, and Social Computing. "MobiLife¿ and "MyLifeBits¿ are the leading projects for representing dailylifeservices and their systems require complicate and collaborative network systems. The collaborative computing environments remain in high potential risks for users' security and privacy because of diverse attack routes. In order to solve the problems, we design combined authentication and multilevel access control, which deals with cryptographic methods in a personal database of "MyLifeBits¿ system. We propose a scheme which is flexible in dynamic access authorization changes, secure against all the attacks from various routes, a minimum round of protocol, privacy preserving access control, and multifunctional.

At CCS'07, a novel identity-based sequential aggregate signature scheme was proposed and the security of the scheme was proven under the hardness assumption of a new computational problem called modified LRSW problem. In the paper, unfortunately, we show that the scheme is universally forgeable, i.e., anyone can generate forged signatures on any messages of its choice. In addition, we show that the computational assumption is not correct by concretely presenting a constant-time algorithm solving the problem. The contribution of the new scheme and assumption is a natural step in cryptologic research that calls for further investigation, which is a step we perform in the current work.

Recently, Baek et al. proposed an efficient public key encryption scheme with keyword search based on the scheme of Boneh et al., However, the security model of Baek et al. seriously limits the ability of the adversary.

The global telecommunication networks would overcome geography and time differences. Recently, telecommunication equipment and service providers seek to connect the wireless mobile telecommunication networks to the Internet directly. These enhanced wireless mobile networks can result in a reorganized set of conventional functions for better developed services.In order to enable these functions, the enhanced all-IP based SS7 communication network is required. The standards associations such as 3rd Generation Partnership Project (3GPP) and 3GPP2 of mobile communication offer the Internet protocol (IP) multimedia sub-system (IMS) as well as the multi-media domain (MMD) systems. The numerous requirements and issues have been emerged in the changeover process of the wireless signaling system no. 7 (SS7) for all-IP network. The crucial point is to ensure interoperability among heterogeneous networks. In this paper, a function named multi-protocol mobility manager (MPMM) is developed. It can satisfy the requirements and issues required in all-IP networks. The proposed MPMM enables roaming functions between 3GPP and 3GPP2 protocols, can reduce the load of the network, and provides other valuable services. The performance of the system is tested and evaluated. From the results of the performance tests, we believe that MPMM can help improve the networks functionalities.

Fathi et al. recently proposed a leakage-resilient authenticated key exchange protocol for a server-client model in mobility environment over wireless links. In the paper, we address flaws in a hash function used in the protocol. The direct use of the hash function cannot guarantee the security of the protocol. We also point out that a combination of the hash function and the RSA cryptosystem in the protocol may not work securely. To remedy these problems, we improve upon the protocol by modifying the hash function correctly.

Abstract Recently, to provide data confidentiality against intermediate relaying proxies, Hur, Shin, and Yoon proposed a decentralized group key management(GKM) scheme for dynamic networks that uses proxy cryptography. We show that the GKM scheme unfortunately does not provide data confidentiality. We also present a counter measure to fix the security breaches. Copyright © 2009 John Wiley & Sons, Ltd.

Multi-receiver Identity-Based Key Encapsulation Mechanism (mIB-KEM) allows a sender to distribute messages for a set of receivers using the receiver's identity as a public key. Recently, Chatterjee and Sarkar [12] suggested a new mIB-KEM which has sublinear-size ciphertexts and private keys simultaneously. They demonstrated that their scheme is secure against chosen plaintext (or ciphertext) attacks without random oracles. In this paper, we show that their scheme is not secure in that a revoked user can easily decrypt cipher-texts. We next propose a new mIB-KEM which overcomes the security flaw identified in the construction of Chatterjee and Sarkar.

In a real world, it is often in a group setting that sensitive information has to be stored in databases of a server. Although personal information does not need to be stored in a server, the secret information shared by group members is likely to be stored there. The shared sensitive information requires more security and privacy protection. To our best knowledge, there is no paper which deals with applicable group search schemes to a real world over encrypted data. In this paper, we propose two schemes which can search the encrypted documents without re-encrypting all documents in a server even if group keys have to be updated. The schemes can support general database normalization for encrypted database. Our experiments show that our schemes are much more efficient than the existing schemes.

Recently, some random key pre-distribution approaches have been proposed for pair-wise key establishment in sensor networks recently. Unfortunately, all of them have the following problem if some sensor nodes are captured by an attacker. Some pair-wise keys of non-captured nodes can be compromised. In this paper, we propose a novel key distribution scheme with strong resilience against node capture.

We suggest a linkable ring signature scheme providing strong anonymity and weak linkability. We show that our linkable ring signature scheme can be used to construct a selectively linkable ring signature scheme, an efficient convertible (verifiable) ring signature scheme, and an efficient deductible ring signature scheme.

In this paper, we propose UsMSS (User-centric secure Multimedia Service System) which provides interoperability of multimedia contents among incompatible devices in intelligent home. In addition, an authentication method suitable for the intelligent home is suggested. Furthermore, the proposed system provides intelligent services by reflecting context information (user preference, user location, device status information, etc.) through a sensor network module and home server, providing transparent and secure service.