• Review of KIISC
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• v.9 no.1
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• pp.33-42
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• 1999

본 논문에서는 지금까지 알려진 확률 공개키 암호 방식에 대해서 조사 분석한다. 기존의 결정적(deterministic) 공개키 방식의 문제점을 논하고, 결정적 공개키 방식에서는 이물 수 없는 강한 안전성 개념들을 소개한다. 그리고 결정적 공개키 방식의 문제점을 보완하고 제시된 안전성 개념을 충족시키는 확률 공개키 암호 방식에 대하여 고찰한다. 또한, 조사한 확률 공개키 방식을 종합적으로 비교 분석한다.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.28 no.8C
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• pp.756-764
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• 2003

We investigate a probabilistic public key cryptosystem proposed by Paillier. It is based on the discrete logarithmic function and the messages are calculated from the modular product of two those functions, one of which has a fixed value depending on a given public key. The improvement is achieved by a good choice for the public key so that it is possible to get efficient schemes without losing the onewayness and semantic security. Also we suggest the method to get the public key for our schemes.

• Proceedings of the Korea Information Processing Society Conference
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• 2002.11b
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• pp.1083-1086
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• 2002

1999년에 Paillier는 합성수 잉여류(composite residuosity class)에 기반을 둔 공개키 암호 방식을 제안하였다. 이는 고차 잉여를 결정하는 것이 계산상 어렵다는 가정 아래 제안된 새로운 확률 암호 방식이다. 현재, 이 새로운 공개키 암호 방식에 대한 안전성 및 변형된 Paillier 암호 방식들에 대한 연구가 다양한 방향에서 진행되고 있다. 요즘, 암호 알고리즘 연구에서 가장 활발하게 연구되고 있는 Paillier 암호 방식에 대하여 그 내용과 안전성에 대하여 수학적으로 자세히 분석하고, 개선된 Paillier 방식의 안전성과 선택적 암호문 공격에 대하여 분석하였나. 이후, Paillier 방식과 개선된 Paillier 방식의 효율성 및 안전성을 비교한다.

• Journal of KIISE:Information Networking
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• v.29 no.4
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• pp.346-351
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• 2002

We improve a new probabilistic public key cryptosystem, in which the one wav function was defined only on the discrete logarithmic functions, proposed by Okamoto and Uchiyama. The plaintexts are calculated from the modular product of two these functions, one of which has a fixed value depending on a given public key. The improvement is achieved by a well-chosen public key assuming an unit element 1 as the fixed function value. Because it is possible to reduce the number of operations at the decryption. Also the concrete method for a public key of our improved scheme is suggested.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.24 no.5
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• pp.781-793
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• 2014

A Public Key Infrastructure (PKI) is security standards to manage and use public key cryptosystem. A PKI is used to provide digital signature, authentication, public key encryption functionality on insecure channel, such as E-banking and E-commerce on Internet. A soft-token private key in PKI is leaked easily because it is stored in a file at standardized location. Also it is vulnerable to a brute-force password attack as is protected by password-based encryption. In this paper, we proposed a new method that detects private key compromise and is probabilistically secure against a brute-force password attack though soft-token private key is leaked. The main idea of the proposed method is to use a genuine signature key pair and (n-1) fake signature key pairs to make an attacker difficult to generate a valid signature with probability 1/n even if the attacker found the correct password. The proposed method provides detection and notification functionality when an attacker make an attempt at authentication, and enhances the security of soft-token private key without the additional cost of construction of infrastructure thereby extending the function of the existing PKI and SSL/TLS.