Jen-Chun Chang

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—Mappings of the set of binary vectors of a fixed length to the set of permutations of the same length are useful for the construction of permutation codes. In this correspondence, several explicit constructions of such mappings preserving or increasing the Hamming distance are given. Some applications are given to illustrate the usefulness of the(More)
Mappings from the set of binary vectors of a fixed length to the set of permutations of the same length that strictly increase Hamming distances except when that is obviously not possible are useful for the construction of permutation codes. In this correspondence, we propose recursive and explicit constructions of such mappings. Some comparisons show that(More)
We study the problem how to construct an RFID mutual authentication protocol between tags and readers. Juels (in Journal on Selected Areas in Communications, 2006) proposed an open question which asks whether there exists a fully privacy-preserving RFID authentication protocol in which the time complexity of a successful authentication phase can be done in(More)
In this correspondence, for any k ges 2, we first propose two constructions of (n,k) distance-increasing mappings (DIMs) from the set of binary vectors of length n to the set of permutations of the same length that strictly increase the Hamming distance by at least k except when it is obviously not possible. Next, we prove that for any k ges 2, there is a(More)
Permutation arrays have found applications in powerline communication. One construction method for permutation arrays is to map good codes to permutations using a distance-preserving mappings (DPM). DPMs are mappings from the set of all q-ary vectors of a fixed length to the set of permutations of some fixed length (the same or longer) such that every two(More)
—In this paper, we propose a new approach to establishing application layer conference trees for multimedia multi-point conferences on the Internet using the Megaco/H.248 protocol, a Voice over IP (VoIP) media gateway control protocol. In existing VoIP protocols (and also legacy telephone networks), a multipoint conference takes place through an MCU, and(More)
In this paper, we develop a watermarking scheme for image authentication and verification. The watermarking scheme for tamper detection of an image is fragile and block-based. Such a scheme has good tamper localization and high tamper detection rate. The security of our scheme depends on a secret key, even though the attacker got the original watermark(More)
Distance-preserving mappings (DPMs) are mappings from the set of all q-ary vectors of a xed length to the set of permutations of the same or longer length such that every two distinct vectors are mapped to permutations with the same or even larger Hamming distance than that of the vectors. In this paper, we propose a construction of DPMs from ternary(More)
A consecutive-k-n network is a generalization of the well-known consecutive -k-out-of-n system, and has many practical applications. This network consists of n + 2 nodes (node 0, the source, nodes 1, 2, …, n, and node n + 1, the target) and directed links from node i to node j (0 ≤ i < j ≤ n + 1, j − i ≤ k). Because all nodes except the source and target,(More)