Improvement on the Cheater Identifiable Threshold Scheme

Hidenori KUWAKADO  Hatsukazu TANAKA  

IEICE TRANSACTIONS on Fundamentals of Electronics, Communications and Computer Sciences   Vol.E84-A   No.4   pp.957-960
Publication Date: 2001/04/01
Online ISSN: 
Print ISSN: 0916-8508
Type of Manuscript: Special Section LETTER (Special Section on Fundamentals of Information and Communications)
information security,  secret sharing,  authentication code,  erasure decoding,  cheater,  

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Kurosawa, Obana, and Ogata proposed a (k,n) threshold scheme such that t cheaters can be identified, where t (k-1)/3. Their scheme is superior to previous schemes with respect to the number of participants for identifying cheaters and the size of a share. In this paper, we improve the detectability of their scheme. By using erasure decoding and the authentication code, we show that cheaters less than k/2 can be identified. Although the size of a share is larger than that of their scheme, it is independent of n.