Comment on "Quantum key distribution for d-level systems with generalized Bell states" [Phys. Rev. A 65, 052331 (2002)]

In the paper [Phys. Rev. A 65, 052331(2002)], an entanglement-based quantum key distribution protocol for d-level systems was proposed. However, in this Comment, it is shown that this protocol is insecure for a special attack strategy.Comment: 4 pages, 4 figure

Comment on "Quantum secret sharing based on reusable Greenberger-Horne-Zeilinger states as secure carriers" [Phys. Rev. A 67, 044302 (2003)]

In a recent paper [S. Bagherinezhad and V. Karimipour, Phys. Rev. A 67, 044302 (2003)], a quantum secret sharing protocol based on reusable GHZ states was proposed. However, in this Comment, it is shown that this protocol is insecure if Eve employs a special strategy to attack.Comment: 2 pages, no figure

Dense-Coding Attack on Three-Party Quantum Key Distribution Protocols

Cryptanalysis is an important branch in the study of cryptography, including both the classical cryptography and the quantum one. In this paper we analyze the security of two three-party quantum key distribution protocols (QKDPs) proposed recently, and point out that they are susceptible to a simple and effective attack, i.e. the dense-coding attack. It is shown that the eavesdropper Eve can totally obtain the session key by sending entangled qubits as the fake signal to Alice and performing collective measurements after Alice's encoding. The attack process is just like a dense-coding communication between Eve and Alice, where a special measurement basis is employed. Furthermore, this attack does not introduce any errors to the transmitted information and consequently will not be discovered by Alice and Bob. The attack strategy is described in detail and a proof for its correctness is given. At last, the root of this insecurity and a possible way to improve these protocols are discussed.Comment: 6 pages, 3 figure

The Effects of Social Messaging on Students’ Learning and Intrinsic Motivation in Peer Assessment

This study aims to gain a better understanding of how the newly arisen social messaging may impact the practice of peer assessment. Seventy-nine ESL (English as Second Language) students reviewed each other’s English essays in three peer assessment groups: a three-member group using wiki (wiki group), a three-member group using social messaging (small messaging group), and a six-member group using social messaging (big messaging group). Data analysis suggested that peer assessment facilitated by social messaging can be at least of the same effectiveness as wiki-facilitated peer assessment on ESL students’ writing skills and intrinsic motivation. In addition, the findings indicated that students in the small messaging group outperformed students in the big messaging group on essay writing, and reported a significantly higher rating on Perceived Competence, a positive indicator of the behavioral measures of intrinsic motivation, than students in the big messaging group