• Proceedings of the Korea Institutes of Information Security and Cryptology Conference
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• 2001.11a
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• pp.79-82
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• 2001

사용자와 서비스 제공자가 인증을 수행할 경우 사용자의 신원이 노출되는 문제가 사회의 큰 이슈로 떠오르고 있으며, 이러한 문제점을 해결하기 위해서 신원 위탁 방식이 제시되었다. 신원 위탁 방식에서는 사용자의 정확한 신원을 가지고 있는 발행자가 사용자에게 인증 정보를 전달하고, 사용자는 이것을 이용해 익명성을 유지한 채로 서비스 제공자와 인증 단계를 수행하게 된다. 본 논문에서는 신원 위탁 방식의 안전성과 신뢰성을 위한 새로운 요구사항을 제시하고 이를 만족할 수 있는 새로운 신원 위탁 방식을 제안한다.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.12 no.3
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• pp.119-128
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• 2002

In case certification between user and service provider is achieved, problem that user's identity is revealed is occurring by social issue, so it was presented identity escrow scheme to solve these problem. In identity escrow scheme, the issuer who have correct user's identity transmits securely anonymity authentication information to user, and user achieves authentication phase with service provider keeping oneself anonymity using this. In this paper, we present requirement for security and trusty of identity escrow scheme and propose new mechanism that can security this. Also, propose method that service provider can deliver securely contents to user and propose mechanism that improve that support ky recovery at encryption communication that using secret key that it was generated by key agreement between users.

• Journal of Korea Multimedia Society
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• v.3 no.6
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• pp.617-624
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• 2000

We introduce the concept of a Identity Escrow Scheme, an application of key escrow ideas to solve the problem of authentication. In the Identity Escrow Scheme, the User escrows a own real identity to the Issuer and receives a Authentication Information. In authentication step, between the User to the Service Provider, the User only gives a Authentication Information to the Service Provider. Therefore, the Service Provider don't know a real identity of user's. However, when the User does unlawful actions, the Lawful Agent is called by the Service Provider, and his anonymity is revoked by cooperation of the Issuer and the Lawful Agent. We propose new Identity Escrow Schemes and analyze these.

• Proceedings of the Korea Multimedia Society Conference
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• 2000.04a
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• pp.82-85
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• 2000

인터넷 환경의 발달에 의해서 사용자의 편리성은 증가하였지만, 사용자의 프라이버시가 노출되는 위험 또한 증가하였다. 그 중에서 사용자의 신원이 인증 절차에서 서비스 제공자에게 노출됨으로 사용자 프라이버시 침해 문제가 발생할 수있는데 , 본 논문에서는 인증 절차시 사용자의 익명성을 제공하고 유사시 제 3의 기관과 협력해서 익명성을 제거할 수 있는 새로운 신원위탁방식을 제안한다.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.20 no.6
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• pp.1-8
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• 2019

Medical information is an important personal information for patients, and it must be protected. In particular, when medical personnel approach electronic medical records, authentication for enhanced security is essential. However, the existing public certificate-based certification model did not reflect the security characteristics of the electronic medical record(EMR) due to problems such as personal key management and authority delegation. In this study, we propose a fingerprint recognition-based authentication model with enhanced security to solve problems in the approach of the existing electronic medical record system. The proposed authentication model is an EMR system based on fingerprint recognition using PEMS (Private-key Escrow Management Server), which is applied with the private key commission protocol and the private key withdrawal protocol, enabling the problem of personal key management and authority delegation to be resolved at source. The performance experiment of the proposed certification model confirmed that the performance time was improved compared to the existing public certificate-based authentication, and the user's convenience was increased by recognizing fingerprints by replacing the electronic signature password.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.11 no.12
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• pp.2271-2279
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• 2007

In this paper, we introduce the notion of certificate-based encryption in multi-receiver environment, which avoids the inherent key escrow problem while preserving the implicit certification in identity-based encryption. We also construct a highly efficient certificate-based encryption scheme for multi-receiver environment, which eliminates pairing computation to encrypt a message for multiple receivers. Moreover, the proposed scheme only needs one pairing computation for decrypting the ciphertext. We compare our scheme with the most efficient identity-based encryption scheme for multi-receiver environment proposed by Baek et.al.[1] in terms of the computational point of view, and show that our scheme provides better efficiency than Baek's scheme. Finally, we discuss how to properly transform our scheme into a new public key broadcast encryption scheme based on subset-cover framework.

• Journal of Korea Multimedia Society
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• v.14 no.6
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• pp.775-784
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• 2011

In this paper we introduce the notion of multi-receiver certificateless encryption that avoids the inherent key escrow problem of multi-receiver identity-based encryption, and also present a highly efficient multi-receiver certificateless encryption scheme which eliminates pairing computation to encrypt a message for multiple receivers, Moreover, the proposed scheme only needs one pairing computation to decrypt the ciphertext. Finally, we discuss how to properly transform our scheme into a new public key broadcast encryption scheme for stateless receivers based on the subset-cover framework, which enjoys the advantages of certificateless cryptography.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.19 no.6
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• pp.17-22
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• 2009

Certificateless cryptography eliminates the need of certificacates in the public key crytosystems and solves the inherent key escrow problem in identity-based cryptosystems. This paper demonstrates that two certificateless signature schemes proposed by Guo et al. and Wang et al. respectively are insecure against key replacement attacks by a type I adversary. We show that the adversary who can replace a signer's public key can forge signatures under the replaced public key. We then make a suggestion to prevent the attacks.