Seong-Min Hong

New modular multiplication algorithms for fast modular exponentiation

A modular exponentiation is one of the most important operations in public-key cryptography. However, it takes much time because the modular exponentiation deals with very large operands as 512-bit integers. The modular exponentiation is composed of repetition of modular multiplications. Therefore, we can rcducc the execution time of it by reducing thc execution time of each modular multiplication. In this paper, we propose two fast modular multiplication algorithms. One is for modular multiplications between different integers, and the other is for modular squarings. These proposed algorithms require single-precision multiplications fewer than those of Montgomery modular multiplication algorithms by 1/2 and 1/3 times, respectively. Implementing on PC, proposed algorithms reduce execution times by 50% and 30% compared with Montgomery algorithms, respectively.

Trust management for resilient wireless sensor networks

Utilities of wireless sensor networks are standing out in bold relief in various fields such as home environmental, industrial, and military applications. Compared with the vivid applications of the sensor networks, however, the security and privacy issues of the sensor networks are still in their infancy because unique features of the sensor networks make it difficult to adopt conventional security policies. Especially, false reports are critical threats because they can drain out the finite amount of energy resources in a battery-powered sensor networks; thus, a novel trust management scheme is necessary to make resilient wireless sensor networks. Cryptographic authentication mechanisms and key management schemes cannot suggest solutions for the real root of the problem. In this paper, we propose a trust management scheme which can identify trustworthiness of sensor nodes and suggest a defensible approach against insider attacks beyond conventional cryptographic approaches.

On the construction of a powerful distributed authentication server without additional key management

The extensive use of networks and distributed systems has increased the need for authentication and digital signatures. In performing authentication on a massive scale, authentication servers that use multiple workstations or PCs are more economical than servers that use one minicomputer or mainframe. However, the establishment of authentication servers with multiple platforms can cause some security problems and increase the cost of key management because all platforms within the server must have the private key of the authentication server. We propose a model for a distributed authentication server, in which one platform keeps the secret information, while the other platforms just do calculations (therefore, no additional key management).

Secure group communication with multiplicative one-way functions

Secure group communication enables only the users in that group securely communicate with each other. Because the users can join or leave the group dynamically, scalability is a major concern. In this paper, we propose a communication-efficient model using multiplicative one-way functions. It also has well known tree-based structure but uses exclusive keys that are held by the users not in some subtree. When totally n users are in the group, proposed model reduces the size of multicast message required in join or leave operation from O(logn) to O(1) keeping other costs comparable. The security of proposed model is based on the difficulty of finding square root modulo composite number and it also satisfies both forward and backward secrecy. Therefore, proposed model is very applicable to a wide area network environment or a low-bandwidth channel such as ad hoc network.

Accelerating Key Establishment Protocols for Mobile Communication

Mobile communication is more vulnerable to security attacks such as interception and unauthorized access than fixed network communication. To overcome these problems, many protocols have been proposed to provide a secure channel between a mobile station and a base station. However, the public-key based protocols are not fully utilized due to the poor computing power and the small battery capacity of a mobile station. In this paper, we propose some techniques accelerating public-key based key establishment protocols between a mobile station and a base station. The proposed techniques enable a mobile station to borrow computing power from a base station without revealing its secret information. The proposed schemes accelerate the previous protocols up to five times and reduce the amount of power consumption of a mobile station. The proposed schemes use SASC (Server-Aided Secret Computation) protocols that are used for smart cards. Our insight is that the unbalanced property in computing power of the mobile communication is similar to that of the smart card system. The acceleration degrees of the proposed schemes are quite different from one another according to the used SASC protocols. In this paper, we analyze the acceleration factors of the proposed schemes and compare them with one another. The analysis shows that one of the approach presents outstanding performance among them.

Impact angle control guidance synthesis for evasive maneuver against intercept missile

This paper proposes a synthesis of new guidance law to generate an evasive maneuver against enemy’s missile interception while considering its impact angle, acceleration, and field-of-view constraints. The first component of the synthesis is a new function of repulsive Artificial Potential Field to generate the evasive maneuver as a real-time dynamic obstacle avoidance. The terminal impact angle and terminal acceleration constraints compliance are based on Time-to-Go Polynomial Guidance as the second component. The last component is the Logarithmic Barrier Function to satisfy the field-of-view limitation constraint by compensating the excessive total acceleration command. These three components are synthesized into a new guidance law, which involves three design parameter gains. Parameter study and numerical simulations are delivered to demonstrate the performance of the proposed repulsive function and guidance law. Finally, the guidance law simulations effectively achieve the zero terminal miss distance, while satisfying an evasive maneuver against intercept missile, considering impact angle, acceleration, and field-of-view limitation constraints simultaneously.

Securing mobile agents by integrity-based encryption

The mobile agent paradigm is an important and promising technology to structure distributed applications. Since the mobile agent physically moves to a remote host that is under the control of a different principal, it needs to be protected from this environment which is responsible for its execution. This problem constitutes the major difficulty for using the mobile agent paradigm for privacy protection and is explored in great detail. In this paper, we provide the methodology of protecting the mobile agents from unauthorized modification for the program code or data by malicious hosts. One important technique is an integrity-based encryption, by which a mobile agent, while running on the remote host, checks itself to verify that it has not been modified and conceals some privacy sensitive parts of the mobile agent

Three-dimensional velocity maximizing agile turn of air-to-air missile with collision triangle constraint

This paper expands the two-dimensional control laws for agile turn of air-to-air missile during initial boost phase to three-dimensions. Optimal solution for agile turn is obtained in vector form using optimal control theory with simplified Pseudo-spectral missile dynamics model. Both cases with and without analytical solution are reviewed. Collision triangle conditions are obtained from vector geometry. The performance of proposed initial guidance is compared with Proportional Navigation Guidance law under different engagement geometries. Simulations verify that proposed method yields improved results.

Stage optimization of multi-stage anti-air missile using co-evolutionary augmented Lagrangian method

This paper deals with a stage optimization problem of multi-stage missile. The missile covered in the study is three-stage missile, of which the first and second stages have propulsion system and the third stage is a kill vehicle to intercept a target. An evolutionary based optimization algorithm is used to optimize the propulsion stage weights of the missile. To deal with a trajectory optimization problem simultaneously, linear tangent law and proportional navigation guidance law are implemented to the optimization algorithm. Subsystem parameters, such as thrust, specific impulse, body diameter, and aerodynamic coefficients are considered as design requirements, so they are given in advance. The goal of the problem is to minimize the total system weight for cost savings. In order to verify the result from the evolutionary algorithm, optimization results via a pseudo-spectral method are compared. At the same time, the limit of gradient-based search method is discussed.

Rogue Public Key Registration Attack and the Importance of 'Proof of Possession' in the PKI Environment*This work was supported by the Ministry of Science and Technology (MOST)/Korea Science and Engineering Foundation (KOSEF) through the Advanced Information Technology Research Center (AITrc) and the MIC (Ministry of Information and Communication), Korea, under the ITRC (Information Technology Research Center) support program supervised by the IITA (Institute of Information Technology Assessment).

The security vulnerabilities of a number of provable secure proxy signature schemes are examined with the assumption that users can register their public keys without having corresponding private keys. This assumption is different from that of a standard proxy signature in which the public keys of users are authentic. Under this assumption, both the Triple Schnorr scheme and Kang et als scheme are shown to be vulnerable to a rogue public key registration attack. This attack gives an adversary the ability to generate a proxy signature without the valid agreement of the original signer. Moreover, it is shown that an adversary can manipulate the description of a delegated signing right at will. This work can be considered as an awakening to the importance of Proof of Possession (PoP) in the PKI environment, as in many cases certificate authorities do not require the PoP protocol, as has been stated [1].