Security Analysis of Zhu-Bao's Verifiably Committed Signature

Dae Hyun YUM  Pil Joong LEE  

IEICE TRANSACTIONS on Fundamentals of Electronics, Communications and Computer Sciences   Vol.E90-A   No.12   pp.2962-2964
Publication Date: 2007/12/01
Online ISSN: 1745-1337
DOI: 10.1093/ietfec/e90-a.12.2962
Print ISSN: 0916-8508
Type of Manuscript: LETTER
Category: Information Security
fair exchange,  verifiably encrypted signature,  cryptanalysis,  

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A fair exchange scheme is a protocol by which two parties Alice and Bob swap items or services without allowing either party to gain an advantage by quitting prematurely or otherwise misbehaving. Verifiably committed signature is a generalized and unified model for non-interactive optimistic fair exchange scheme. The state-of-the-art verifiably committed signature that enjoys the off-line, setup-free and stand-alone properties is due to Zhu and Bao [1]. In this article, we show that the Zhu-Bao's verifiably committed signature is insecure in the multi-user setting and then consider possible countermeasures.