Showing papers by "Chiu C. Tan published in 2011"

IMDGuard: Securing implantable medical devices with the external wearable guardian

Abstract: Recent studies have revealed security vulnerabilities in implantable medical devices (IMDs). Security design for IMDs is complicated by the requirement that IMDs remain operable in an emergency when appropriate security credentials may be unavailable. In this paper, we introduce IMDGuard, a comprehensive security scheme for heart-related IMDs to fulfill this requirement. IMDGuard incorporates two techniques tailored to provide desirable protections for IMDs. One is an ECG based key establishment without prior shared secrets, and the other is an access control mechanism resilient to adversary spoofing attacks. The security and performance of IMDGuard are evaluated on our prototype implementation.

A Timing-Based Scheme for Rogue AP Detection

Abstract: This paper considers a category of rogue access points (APs) that pretend to be legitimate APs to lure users to connect to them. We propose a practical timing-based technique that allows the user to avoid connecting to rogue APs. Our detection scheme is a client-centric approach that employs the round trip time between the user and the DNS server to independently determine whether an AP is a rogue AP without assistance from the WLAN operator. We implemented our detection technique on commercially available wireless cards to evaluate their performance. Extensive experiments have demonstrated the accuracy, effectiveness, and robustness of our approach. The algorithm achieves close to 100 percent accuracy in distinguishing rogue APs from legitimate APs in lightly loaded traffic conditions, and larger than 60 percent accuracy in heavy traffic conditions. At the same time, the detection only requires less than 1 second for lightly-loaded traffic conditions and tens of seconds for heavy traffic conditions.

Reliable Re-Encryption in Unreliable Clouds

Abstract: A key approach to secure cloud computing is for the data owner to store encrypted data in the cloud, and issue decryption keys to authorized users. Then, when a user is revoked, the data owner will issue re-encryption commands to the cloud to re-encrypt the data, to prevent the revoked user from decrypting the data, and to generate new decryption keys to valid users, so that they can continue to access the data. However, since a cloud computing environment is comprised of many cloud servers, such commands may not be received and executed by all of the cloud servers due to unreliable network communications. In this paper, we solve this problem by proposing a time-based re-encryption scheme, which enables the cloud servers to automatically re-encrypt data based on their internal clocks. Our solution is built on top of a new encryption scheme, attribute-based encryption, to allow fine-grain access control, and does not require perfect clock synchronization for correctness.

Friendship-based location privacy in Mobile Social Networks

Abstract: Location privacy in Mobile Social Networks (MSNs) has generated significant interest in recent years, with many proposed methods to address the problem. Commercial solutions to this problem have suggested designing better ways for users to determine when to report their locations, while academic researchers have proposed solutions that involve deploying trusted third party servers to protect user privacy. In this paper, we showed that simply omitting location updates does not provide adequate privacy protections, especially in situations where the friendship relationships between users are known. We proposed a fake location update algorithm that allows a user to protect his privacy. A key feature of our approach is that it can be adopted without the use of any third party services, making them more practical. We evaluate our approach using extensive simulation experiments.

Public-key based access control in sensornet

Abstract: Symmetric cryptography has been mostly used in security schemes in sensor networks due to the concern that public key cryptography (PKC) is too expensive for sensor devices. While these schemes are efficient in processing time, they generally require complicated key management, which may introduce high memory and communication overhead. On the contrary, PKC-based schemes have simple and clean key management, but cost more computational time. The recent progress in PKC implementation, specially elliptic curve cryptography (ECC), on sensors motivates us to design a PKC-based security scheme and compare its performance with the symmetric-key counterparts. This paper proposes a practical PKC-based access control for sensor networks, which consists of pairwise key establishment, local access control, and remote access control. We have implemented both cryptographic primitives on commercial off-the-shelf sensor devices. Building the user access control as a case study, we show that PKC-based protocol is more advantageous than those built on symmetric cryptography in terms of the memory usage, message complexity, and security resilience. Meanwhile, our work also provides insights in integrating and designing PKC-based security protocols for sensor networks.

Enhancing Mobile Social Network Privacy

Abstract: Privacy is an important concern for location based services (LBSs). In this paper, we consider a specific type of LBS known as a mobile social network (MSN). We demonstrate a new type of attack, where an adversary can combine the location and friendship information found in a MSN, to violate user privacy. We propose a fake location reporting solution that does not require any additional trusted third party deployment. We use extensive simulations to determine the validity of our scheme.

Defending against vehicular rogue APs

Abstract: This paper considers vehicular rogue access points (APs) that rogue APs are set up in moving vehicles to mimic legitimate roadside APs to lure users to associate to them. Due to its mobility, a vehicular rogue AP is able to maintain a long connection with users. Thus, the adversary has more time to launch various attacks to steal users' private information. We propose a practical detection scheme based on the comparison of Receive Signal Strength (RSS) to prevent users from connecting to rogue APs. The basic idea of our solution is to force APs (both legitimate and fake) to report their GPS locations and transmission powers in beacons. Based on such information, users can validate whether the measured RSS matches the value estimated from the AP's location, transmission power, and its own GPS location. Furthermore, we consider the impact of path loss and shadowing and propose a method based on rate adaption to deal with advanced rogue APs. We implemented our detection technique on commercial off-the-shelf devices including wireless cards, antennas, and GPS modules to evaluate the efficacy of our scheme.

Secure Locking for Untrusted Clouds

Abstract: Migrating applications with strong consistency requirements to public cloud platforms remains risky since the data owner cannot verify the correctness of the public cloud's locking algorithm. In this paper, we identify new attacks that an untrusted cloud provider can launch via control of the locking mechanism, and propose an extension to existing locking scheme to address such attacks. Our solution modifies the locks to include a short history to allow \textit{data users} to determine correctness, and can also prevent the cloud from re-ordering operations for financial gain.

A Timing-Based Scheme for

Abstract: This paper considers a category of rogue access points (APs) that pretend to be legitimate APs to lure users to connect to them. We propose a practical timing-based technique that allows the user to avoid connecting to rogue APs. Our detection scheme is a client-centric approach that employs the round trip time between the user and the DNS server to independently determine whether an AP is a rogue AP without assistance from the WLAN operator. We implemented our detection technique on commercially available wireless cards to evaluate their performance. Extensive experiments have demonstrated the accuracy, effectiveness, and robustness of our approach. The algorithm achieves close to 100 percent accuracy in distinguishing rogue APs from legitimate APs in lightly loaded traffic conditions, and larger than 60 percent accuracy in heavy traffic conditions. At the same time, the detection only requires less than 1 second for lightly-loaded traffic conditions and tens of seconds for heavy traffic conditions.

The Future in Mobile Multicore Computing

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