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A Short and Efficient Redactable Signature Based on RSA
Seongan Lim,이향숙 한국전자통신연구원 2011 ETRI Journal Vol.33 No.4
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.
Analysis of privacy-preserving element reduction of a multiset
서재홍,HyoJin Yoon,Seongan Lim,천정희,홍도원 대한수학회 2009 대한수학회지 Vol.46 No.1
The element reduction of a multiset S is to reduce the number of repetitions of an element in S by a predetermined number. Privacy-preserving element reduction of a multiset is an important tool in private computation over multisets. It can be used by itself or by combination with other private set operations. Recently, an efficient privacy-preserving element reduction method was proposed by Kissner and Song [7]. In this paper, we point out a mathematical flaw in their polynomial representation that is used for the element reduction protocol and provide its correction. Also we modify their over-threshold set-operation protocol, using an element reduction with the corrected representation, which is used to output the elements that appear over the predetermined threshold number of times in the multiset resulting from other privacy-preserving set operations.
Security Analysis of a Certificateless Signature from Lattices
Chang, Seunghwan,Lee, Hyang-Sook,Lee, Juhee,Lim, Seongan Hindawi Limited 2017 Security and communication networks Vol.2017 No.-
<P>Tian and Huang proposed a lattice-based CLS scheme based on the hardness of the SIS problem and proved, in the random oracle model, that the scheme is existentially unforgeable against strong adversaries. Their security proof uses the general forking lemma under the assumption that the underlying hash function H is a random oracle. We show that the hash function in the scheme is neither one-way nor collision-resistant in the view of a strong Type 1 adversary. We point out flaws in the security arguments and present attack algorithms that are successful in the strong Type 1 adversarial model using the weak properties of the hash function.</P>