• ETRI Journal
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• v.33 no.4
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• pp.621-628
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• 2011

The redactable signature scheme was introduced by Johnson and others in 2002 as a mechanism to support disclosing verifiable subdocuments of a signed document. In their paper, a redactable signature based on RSA was presented. In 2009, Nojima and others presented a redactable signature scheme based on RSA. Both schemes are very efficient in terms of storage. However, the schemes need mechanisms to share random prime numbers, which causes huge time consuming computation. Moreover, the public key in the scheme of Johnson and others is designed to be used only once. In this paper, we improve the computational efficiency of these schemes by eliminating the use of a random prime sharing mechanism while sustaining the storage efficiency of them. The size of our signature scheme is the same as that of the standard RSA signature scheme plus the size of the security parameter. In our scheme, the public key can be used multiple times, and more efficient key management than the scheme of Johnson and others is possible. We also prove that the security of our scheme is reduced to the security of the full domain RSA signature scheme.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.13 no.2
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• pp.49-61
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• 2003

Electronic voting schemes must provide universal verifiability and receipt-freeness, as well as basic properties such as privacy, eligibility, to make the election fair and transparent. But it is difficult to provide both universal verifiability and receipt-freeness because they are mutually contradictory in their objective. To date, most electronic voting schemes provide only one of these properties and those few that provide both properties are not practical due to heavy computational load. In this paper, we present an efficient electronic voting scheme that provides both properties. The proposed scheme uses a trusted third party called HR(Honest Randomizer) and requires only one-way untappable channels from HRs to voters. Among the schemes that assume only one-way untappable channel this scheme requires the least amount of computation. Among the schemes that provide both properties, this scheme uses the weakest physical assumption. We also discuss the security of the system and compare our scheme with other related schemes.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.31 no.4
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• pp.675-686
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• 2021

According to the recent revision of Privacy Policy and the emerging importance of personal information, cooperations must verify customer identity (Know Your Costomer, KYC) while processing and managing this information so that it does not violate the Privacy Policy. One of the solution of this problem is zero-knowledge proof (ZKP). The use of the ZKP enables to verify the identity without exposing the identity information directly, thereby reducing the burden on the management of personal information while fulfilling the obligation of the cooperations to verify the identity. The ZKP could be employed to many other applications. In this paper, we analyze the ZKP technique and its applications currently being actively studied.