Security Notes on Generalization of Threshold Signature and Authenticated Encryption

Shuhong WANG  Guilin WANG  Feng BAO  Jie WANG  

IEICE TRANSACTIONS on Fundamentals of Electronics, Communications and Computer Sciences   Vol.E87-A   No.12   pp.3443-3446
Publication Date: 2004/12/01
Online ISSN: 
Print ISSN: 0916-8508
Type of Manuscript: LETTER
Category: Information Security
digital signature,  threshold signature,  authenticated encryption,  security,  cryptography,  

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In 2000, Wang et al. proposed a (t,n) threshold signature scheme with (k,l) threshold shared verification, and a (t,n) threshold authenticated encryption scheme with (k,l) threshold shared verification. Later, Tseng et al. mounted some attacks against Wang et al.'s schemes. At the same, they also presented the improvements. In this paper, we first point out that Tseng et al.'s attacks are actually invalid due to their misunderstanding of Wang et al.'s Schemes. Then, we show that both Wang et al.'s schemes and Tseng et al.'s improvements are indeed insecure by demonstrating several effective attacks.