Provably Secure Untraceable Electronic Cash against Insider Attacks

Yoshikazu HANATANI   Yuichi KOMANO   Kazuo OHTA   Noboru KUNIHIRO   

Publication
IEICE TRANSACTIONS on Fundamentals of Electronics, Communications and Computer Sciences   Vol.E90-A   No.5   pp.980-991
Publication Date: 2007/05/01
Online ISSN: 1745-1337
Print ISSN: 0916-8508
Type of Manuscript: Special Section PAPER (Special Section on Discrete Mathematics and Its Applications)
Category: 
Keyword: 
blind multisignature ,  electronic cash ,  provable security ,  random oracle model ,  insider attacks ,  

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Summary: 
Although a great deal of research has been done on electronic cash schemes with blind multisignatures to prevent an insider attack, there is no discussion of a formal security model in the literature. Firstly we discussed the security model of e-cash schemes based on the blind multisignature scheme against a (restricted) attack model and proposed a concrete scheme proven to be secure in the model [1]; however, this attack model disallows an attacker from corrupting an issuing bank and shops in the forgery game. In this paper, first, we reconsider the security model to remove the restriction of the attack model. Second, we propose a new untraceable e-cash scheme with a blind multisignature scheme and prove that the proposed scheme is secure against the (non-restricted) attacks under the DDH assumption in the random oracle model.