Chung-Chih Li

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People enjoy the convenience of on-line services, but online environments may bring many risks. In this paper, we discuss how to prevent users’ passwords from being stolen by adversaries. We propose a virtual password concept involving a small amount of human computing to secure users’ passwords in on-line environments. We adopt user-determined randomized(More)
Modern web applications often suffer from command injection attacks. Even when equipped with sanitization code, many systems can be penetrated due to software bugs. It is desirable to automatically discover such vulnerabilities, given the bytecode of a web application. One approach would be symbolically executing the target system and constructing(More)
People enjoy the convenience of on-line services, Automated Teller Machines (ATMs), and pervasive computing, but online environments, ATMs, and pervasive computing may bring many risks. In this paper, we discuss how to prevent users’ passwords from being stolen by adversaries. We propose a virtual password concept involving a small amount of human computing(More)
In this paper, based on a Linear Congruential Generator (LCG), we propose a new block cipher that is suitable for constructing a lightweight secure protocol for resource-constrained wireless sensor networks. From the cryptanalysis point of view, our building block is considered secure if the attacker cannot obtain the pseudo-random numbers generated by the(More)
Radio Frequency Identification (RFID) systems have provided promising solutions to effective identification of a large number of tagged objects. However, RFID systems suffer from unauthorized tag reading and potential eavesdropping, which becomes a challenging issue because of the shared radio medium and limited size and cost considerations in RFID. In this(More)
In [12] we defined a class of functions called Type-2 Time Bounds (henceforth T2TB) for clocking the Oracle Turing Machine (OTM) in order to capture the long missing notion of complexity classes at type-2. In the present paper we further advance the type-2 complexity theory under our notion of type-2 complexity classes. We have learned that the theory is(More)
Recentadvances inwirelessnetworksandembedded systemshavecreatedanewclass ofpervasive systems such as Wireless Sensor Networks (WSNs) and Radio Frequency IDentification (RFID) systems. WSNs and RFID systems provide promising solutions for a wide variety of applications, particularly in pervasive computing.However, security andprivacy concernshave raised(More)