• 정보보호학회논문지
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• 제13권4호
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• pp.169-176
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• 2003

Distributed signcryption은 특정한 집단에게 서명과 암호가 동시에 된 메시지를 분산시키는 목적으로 설계되었다. 이 signcryption은 unsigncryption 시, 서명자의 공개키를 미리 알고 있어야 서명에 대한 검증을 할 수 있기 때문에 서명자의 익명성을 요하는 전자상거래 응용에서는 부적합하다. 따라서 본 논문에서는 계산량의 증가없이 서명자의 익명성과 신뢰기관에 의한 부인방지(non-repudiation) 기능을 동시에 제공하는 distributed signcryption을 제안하고, 그 안전성과 연산량을 분석한다. 이에 더하여 제안하는 signcryption의 확장으로 집단서명(group signature)의 성질을 가지는 효율적인 집단 signcryption을 제안한다.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제10권5호
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• pp.2407-2426
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• 2016

A group signature scheme allows any member to sign on behalf of a group. It is applied to practical distributed security communication environments, such as privacy-preserving, data mining. In particular, the excellent features of group signatures, including membership joining and revocation, anonymity, traceability, non-frameability and controllable linkability, make group signature scheme more attractive. Among these features, non-frameability can guarantee that a member's signature cannot be forged by any other (including issuer), and controllable linkability supports to confirm whether or not two group signatures are created by the same signer while preserving anonymity. Until now, only Hwang et al.'s group schemes (proposed in 2013 and 2015) can support all of these features. In this paper, we present a new dynamic group signature scheme which can achieve all of the above excellent features. Compared with their schemes, our scheme has the following advantages. Firstly, our scheme achieves more efficient membership revocation, signing and verifying. The cost of update key in our scheme is two-thirds of them. Secondly, the tracing algorithm is simpler, since the signer can be determined without the judging step. Furthermore, in our scheme, the size of group public key and member's private key are shorter. Lastly, we also prove security features of our scheme, such as anonymity, traceability, non-frameability, under a random oracle model.

• 대한수학회보
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• 제46권4호
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• pp.743-769
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• 2009

An ID-based DNF signature scheme is an ID-based signature scheme with an access structure which is expressed as a disjunctive normal form (DNF) with literals of signer identities. ID-based DNF signature schemes are useful to achieve not only signer-privacy but also a multi-user access control. In this paper, we formally define a notion of a (non-interactive) ID-based DNF signature and propose the first noninteractive ID-based DNF signature schemes that are secure under the computational Diffie-Hellman and subgroup decision assumptions. Our first scheme uses random oracles, and our second one is designed without random oracles. To construct the second one, we use a novel technique that converts a non-interactive witness indistinguishable proof system of encryption of one bit into a corresponding proof system of encryption of a bit-string. This technique may be of independent interest. The second scheme straightforwardly yields the first ID-based ring signature that achieves anonymity against full key exposure without random oracles. We finally present two extensions of the proposed ID-based DNF signature schemes to support multiple KGCs and different messages.

• Journal of Communications and Networks
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• 제18권2호
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• pp.190-200
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• 2016

In this paper, we consider some aspects of binding properties that bind an anonymous user with messages. According to whether all the messages or some part of the messages are bound with an anonymous user, the protocol is said to satisfy the full binding property or the partial binding property, respectively. We propose methods to combine binding properties and anonymity-based authenticated key agreement protocols. Our protocol with the full binding property guarantees that while no participant's identity is revealed, a participant completes a key agreement protocol confirming that all the received messages came from the other participant. Our main idea is to use an anonymous signature scheme with a signer-controlled yet partially enforced linkability. Our protocols can be modified to provide additional properties, such as revocable anonymity. We formally prove that the constructed protocols are secure.

• 정보보호학회논문지
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• 제9권4호
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• pp.85-97
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• 1999

은닉 서명 방식은 검증가가 보낸 메시지를 서명자가 그메시지 내용을 보지 못한 채 서명자로부 터 메시지 m에 대한 유효한 서명을 받도록 하는 프로토콜을 말한다. 이것은 만약 은행이 상점과 결탁하 더라도 동전에 대한 사용자를 추적할수 없다는 것을 의미한다. 그러나 사용자의 익명성이 보장되는 전 자화폐는 또한 돈세탁 돈 약탈 그리고 불법적인 구매 행위와 같은 각종 범죄행동을 용이하 게 한다. 이 에 본 논문에서는 국내 전자서명 표준인 KCDSA에 기반하여 공정한 은닉서명을 제안하고 이를 전자화 폐를 부정한 수단으로 이용한 사용자를 추적할수 있는 익명성 제어 기능을 가지고 있다. A blind signature scheme is a protocol allowing verifier to obtain a valid signature for a message m from a signer without him seeing the message. This means that the bank in collaboration with the shop cannot trace the electronic cash to user. However anonymous electronic cash also facilitates fraud and criminal acts such as money laundering anonymous blackmailing and illegal purchaes. Therefore in this paper we propose fair blind signature scheme based on KCDSA which is a domestic digital signature scheme and it apply a electronic cash system. In particularly a proposed electronic cash system have an anonymity control ability which trace a user who make use a electronic cash illegally in association with a trusted center.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제13권3호
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• pp.1546-1565
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• 2019

Signcryption schemes offer the possibility to simultaneously sign and encrypt a message. In order to guarantee the authentication of both signer and receiver in the most efficient way during the signcryption, certificate based solutions have been proposed in literature. We first compare into detail three recently proposed certificate based signcryption systems relying on the elliptic curve discrete logarithm problem and without the usage of compute intensive pairing operations. Next, we demonstrate how the performance of these certificate based systems can be improved by using the Elliptic Curve Qu Vanstone (ECQV) implicit certificates. What is more, generalized signcryption schemes are easily derived from these schemes and the anonymity feature of sender and receiver is already inherently included or can be very efficiently obtained without a significant additional cost.

• 전자공학회논문지CI
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• 제46권1호
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• pp.78-87
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• 2009

속성 기반 서명(Attribute-Based Signature) 기법이란 서명자의 비밀키에 속성 집합(Attribute Set)이 연관되고 서명에 접근구조(Access Structure)가 연관되는 서명 기법이다. 속성 기반 서명 기법은 객체의 식별자가 속성 집합으로 표현되는 속성 기반 시스템(Attribute-Based System) 또는 권한 기반 시스템(Role-Based System)에서 서명자의 익명성과 접근 제어를 가능하게 하는 유용한 서명 기법이다. 본 논문에서는 속성 기반 서명 기법을 정의하고 서명에 포함되는 정책을 DNF(Disjunctive Normal Form) 수식으로 표현이 가능한 효율적인 속성 기반 서명 기법을 제시한다. 제시한 기법은 서명 검증시 상수번의 페어링 연산만이 필요한 최초의 안전한 기법이다. 그리고 증명이 가능한 속성 기반 서명 기법을 구성하기 위해서 새로운 interactive 가정을 소개하고 제안된 기법이 랜덤 오라클과 새로운 가정에서 안전함을 보인다.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제6권10호
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• pp.2692-2707
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• 2012

A separable identity-based ring signature scheme has been constructed as a fundamental cryptographic primitive for protecting user privacy. Using the separability property, ring members can be selected from arbitrary domains, thereby, giving a signer a wide range of ways to control privacy. In this paper we propose a generic method to construct efficient identity-based ring signature schemes with various levels of separability. We first describe a method to efficiently construct an identity-based ring signature scheme for a single domain, in which a signer can select ring identities by choosing from identities defined only for the domain. Next, we present a generic method for linking ring signatures constructed for a single domain. Using this method, an identity-based ring signature scheme with a compact structure, supporting multiple arbitrary domains can be designed. We show that our method outperforms the best known schemes in terms of signature size and computational costs, and that the security model based on the separability of identity-based ring signatures, presented in this paper, is highly refined and effective by demonstrating the security of all of the proposed schemes, using a model with random oracles.

• 한국콘텐츠학회논문지
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• 제9권10호
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• pp.59-66
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• 2009

강한 지정된 검증자 서명(Strong Designated Verifier Signature Scheme)은 지정된 검증자에게 서명자와 같이 서명을 생성할 수 있는 능력을 줌으로써 주어진 서명이 실제 서명자와 검증자 중에 누가 만든 것인지를 알 수 없도록 하는 서명자의 익명성을 보장하는 특별한 서명 방식으로 소프트웨어 분배 또는 전자 투표 등에서 이용될 수 있다. 본 논문에서는, 강한 지정된 검증자 서명 방식의 중요한 성질인 소스 하이딩(source hiding)과 키 노출 공격 (key-compromise attack)의 관계를 살피고 두 성질을 동시에 만족하는 강한 지정된 검증자 서명을 생성할 수 없음을 보인다. 마지막으로 키 노출 공격에 안전한 ID 기반의 강한 지정된 검증자 서명 기법을 제안한다.

• IEIE Transactions on Smart Processing and Computing
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• 제2권2호
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• pp.57-66
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• 2013

Wireless Sensor Networks consist of small, inexpensive, low-powered sensor nodes that communicate with each other. To achieve a low communication cost in a resource constrained network, a novel concept of signcryption has been applied for secure communication. Signcryption enables a user to perform a digital signature for providing authenticity and public key encryption for providing message confidentiality simultaneously in a single logical step with a lower cost than that of the sign-then-encrypt approach. Ring signcryption maintains the signer's privacy, which is lacking in normal signcryption schemes. Signcryption can provide confidentiality and authenticity without revealing the user's identity of the ring. This paper presents the security notions and an evaluation of an ID-based ring signcryption scheme for wireless sensor networks. The scheme has been proven to be better than the existing schemes. The proposed scheme was found to be secure against adaptive chosen ciphertext ring attacks (IND-IDRSC-CCA2) and secure against an existential forgery for adaptive chosen message attacks (EF-IDRSC-ACMA). The proposed scheme was found to be more efficient than scheme for Wireless Sensor Networks reported by Qi. et al. based on the running time and energy consumption.