Hyunrok Lee

A scalable and untraceable authentication protocol for RFID

RFID (Radio Frequency Identification) is recently becoming popular, promising and widespread. In contrast, RFID tags can bring about traceability that causes user privacy and reduces scalability of RFID. Guaranteeing untraceability and scalability at the same time is so critical in order to deploy RFID widely since user privacy should be guaranteed. A large number of RFID protocols were designed in the open literature, but any known protocols do not satisfy untraceability and scalability at the same time to the best of our knowledge. In this paper, we suggest a RFID authentication protocol that guarantees untraceability and scalability together; needless to say preventing several known attacks: replay, spoofing, desyncronization, and cloning by eavesdropping. Our protocol supports ownership transfer and considers multi-tag-reader environment; a reader receives messages from the tags what a reader wants in our protocol. In addition, we address the reason why the item privacy is important, and a way to keep it securely.

New receipt-free voting scheme using double-trapdoor commitment

It is considered to be the most suitable solution for large scale elections to design an electronic voting scheme using blind signatures and anonymous channels. Based on this framework, Okamoto first proposed a receipt-free voting scheme [30] for large scale elections. However, in the following paper, Okamoto [31] proved that the scheme [30] was not receipt-free and presented two improved schemes. One scheme requires the help of the parameter registration committee and the other needs a stronger physical assumption of the voting booth. In this paper, we utilize the double-trapdoor commitment to propose a new receipt-free voting scheme based on blind signatures for large scale elections. Neither the parameter registration committee nor the voting booth is required in our scheme. We also present a more efficient zero-knowledge proof for secret permutation. Therefore, our scheme is much more efficient than Okamotos schemes [30,31] with the weaker physical assumptions. Moreover, we prove that our scheme can achieve the desired security properties.

Enhancements of authenticated multiple key exchange protocol based on bilinear pairings

Lee et al. [4] proposed two new authenticated multiple key exchange protocols based on Elliptic Curve Cryptography (ECC) and bilinear pairings. In this paper, we show an impersonation attack on their pairing-based authenticated key exchange protocol. We demonstrate that any attacker can impersonate an entity to share multiple session keys with another entity of his/her choice by using only the public key of the victim. Moreover, their protocol fails to provide perfect forward secrecy, despite of their claim to the contrary. Thus, we propose a simple modification to the original protocol which avoids our attack.

Open issues in RFID security

RFID security is a relatively new research area. Within less than a decade, a large number of research papers dealing with security issues of RFID technology have appeared. In this paper we attempt to summarize current research works in the field of RFID security and discuss some of their open issues. Firstly, we outline the security threats to RFID, then we summarize some of the current counter-measures and finally, we draw attention to the open issues and challenges in RIFD security.

Efficient authenticated key agreement protocol for dynamic groups

Group key management presents a fundamental challenge in secure dynamic group communications. In this paper, we propose an efficient group authenticated key agreement protocol (EGAKA), which is designed to be fully distributed and fault-tolerant, provides efficient dynamic group membership management, mutual authentication among group members and is secure against both passive and active attacks. The features of EGAKA are as follows: Firstly, EGAKA can be built on any general two-party key exchange protocol without relying on a particular one. EGAKA achieves scalability and robustness in heterogenous environments by allowing members to use any available two-party protocol in common and deliberately designed fault-tolerant mechanism in dynamic membership management. Secondly, EGAKA provides extremely efficient member join services in terms of both communication and computation costs which are constant to the group size. This is a very useful property in the scenarios with frequent member addition.

A survey on RFID security and provably secure grouping-proof protocols

RFID security is a relatively new research area. Within less than a decade, a large number of research papers dealing with security issues of RFID technology have appeared. In the first part of this paper, we attempt to summarise current research in the field of RFID security and discuss some of their open issues. In the second part of this paper, we address some of the open problems we suggested in the first part. In particular, we deal with scalability problem of existing grouping-proof protocols for RFID tags. In addition, we also present the first security definition for a secure grouping-proof protocol for RFID tags. The definition is then used to analyse the security of our proposed grouping-proof protocol which employs a (n, n)-secret sharing scheme to solve the scalability problem of previous protocols.

An enhanced lightweight authentication protocol for access control in wireless LANs

In this paper, an enhanced lightweight identity authentication protocol for access control in IEEE 802.11 networks are presented. The proposed protocol is nicely integrated with the current MAC frame structure and takes the most advantage of the redundancy bits inside the MAC frame header to convey the authentication information, as well as the synchronization information in case of synchronization loss happening. A much more efficient and fault-tolerant synchronization algorithm is given at the same time, which significantly improved the performance of the proposed protocol as compared to the previous ones. The proposed protocol is highly effective as evaluated via a thorough mathematical analysis. A quantitative attack detection framework is also established based on the evaluation result. Finally, the proposed protocol is well suited in a wireless constrained environment for its low communication and computation overheads, requiring only several additional bits (less than 8) for transmission and random bit generating operation.

SPIRAL ARM MORPHOLOGY OF NEARBY GALAXIES

We analyze the spiral structure of 1725 nearby spiral galaxies with redshift less than 0.02. We use the color images provided by the Sloan Digital Sky Survey. We determine the arm classes (grand design, multiple-arm, flocculent) and the broad Hubble types (early, intermediate, late) as well as the bar types (SA, SAB, SB) by visual inspection. We find that flocculent galaxies are mostly of late Hubble type while multiple-arm galaxies are likely to be of early Hubble type. The fractional distribution of grand design galaxies is nearly constant along the Hubble type. The dependence of arm class on bar type is not as strong as that of the Hubble type. However, there is about a three times larger fraction of grand design spirals in SB galaxies than in SA galaxies, with nearly constant fractions of multiple-arm galaxies. However, if we consider the Hubble type and bar type together, grand design spirals are more frequent in early types than in late types for SA and SAB galaxies, while they are almost constant along the Hubble type for SB galaxies. There are clear correlations between spiral structures and the local background density: strongly barred, early-type, grand design spirals favor high-density regions, while non-barred, late-type, flocculent galaxies are likely to be found in low-density regions.

Surface structures on crystalline silicon irradiated by 10 ps laser pulses at 694.3 nm

The grating-like spatially periodic structures are produced on the (100) surfaces of the single crystal silicon by the trains of 10 ps mode-locked ruby laser pulses at the wavelength of 694.3 nm. The periods and orientations of the structures are consistent with the model which involves the interference of the incident light with the surface electromagnetic wave excited through the coupling by surface roughness. Previously unappreciated elliptic ripple patterns are found and explained as the trails of the capillary wave excited on the molten Si surface due to the radially non-uniform deposition of energy.

Multiphoton ionization of aluminum and copper planar target

The total charge of the emitted ions from the planar metal targets irradiated by the mode‐locked ruby laser was measured. The dependence of the total emitted ions on the laser fluence is consistent with the theory of the multiphoton ionization in the low fluence region. However, it shows saturation phenomena at the higher fluence regions. These saturations could be explained by the depletion of the neutral atoms and the level shifting of the intermediate state due to the strong Stark effect.