• 한국컴퓨터정보학회논문지
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• 제22권2호
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• pp.59-63
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• 2017

Recently, Certificate has been loosed 100 times in a four years as Phising or hacking. The service that use certificate in financial services occurs practical and secure issues. Therefore, the Korea government abolished the mandatory system used in the certificate service. However, they did not provide a replacing method for a certificate. And is not to fill the gaps of the certificate with one time password or secure card. Therefore this paper is propose the alternative method with total authentication service, that is lead the more secure electronic commercial.

• 중소기업융합학회논문지
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• 제4권4호
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• pp.25-29
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• 2014

Security is a primary concern in group communication, and secure authentication is essential to establishing a secure group communication. Most conventional authentications consist of knowledge-based and token-based methods. One of the token-based methods is a X.509 certificate, which is used under a Public Key Infrastructure (PKI); it is the most well-known authentication system in a distributed network environment. However, it has a well-known weakness, which only proves the belonging of a certificate. PKI cannot assure identity of a person. The conventional knowledge-based and token-based methods do not really provide positive personal identification because they rely on surrogate representations of the person's identity. Therefore, I propose a secure X.509 certificate with biometric information to assure the identity of the person who uses the X.509 certificate in a distributed computing environment.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제8권7호
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• pp.2554-2571
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• 2014

Certificate-based cryptography is a new cryptographic paradigm that provides an interesting balance between identity-based cryptography and traditional public key cryptography. It not only simplifies the complicated certificate management problem in traditional public key cryptography, but also eliminates the key escrow problem in identity-based cryptography. As an extension of the signcryption in certificate-based cryptography, certificate-based signcryption provides the functionalities of certificate-based encryption and certificate-based signature simultaneously. However, to the best of our knowledge, all constructions of certificate-based signcryption in the literature so far have to be based on the costly bilinear pairings. In this paper, we propose a certificate-based signcryption scheme that does not depend on the bilinear pairings. The proposed scheme is provably secure in the random oracle model. Due to avoiding the computationally-heavy paring operations, the proposed scheme significantly reduces the cost of computation and outperforms the previous certificate-based signcryption schemes.

• 한국컴퓨터정보학회논문지
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• 제22권9호
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• pp.49-55
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• 2017

Despite the Openflow's switch migration occurs after the channel was established in secure manner (optional), the current cryptography protocol cannot prevent the insider attack as the attacker possesses a valid public/private key pair. There are methods such as the certificate revocation list (CRL) or the online certificate status protocol (OCSP) that tries to revoke the compromised certificate. However, these methods require a management system or server that introduce additional overhead for the communication. Furthermore, these methods are not able to mitigate power abuse of an insider. In this paper, we propose a role-based identity-based cryptography (RB-IBC) that integrate the identity of the node along with its role so the nodes within the network can easily mitigate any role abuse of the nodes. Besides that, by combining with IBC, it will eliminate the need of exchanging certificates and hence improve the performance in a secure channel.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제13권3호
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• pp.1502-1522
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• 2019

Leakage of secret keys may be the most devastating problem in public key cryptosystems because it means that all security guarantees are missing. The forward security mechanism allows users to update secret keys frequently without updating public keys. Meanwhile, it ensures that an attacker is unable to derive a user's secret keys for any past time, even if it compromises the user's current secret key. Therefore, it offers an effective cryptographic approach to address the private key leakage problem. As an extension of the forward security mechanism in certificate-based public key cryptography, forward-secure certificate-based signature (FS-CBS) has many appealing merits, such as no key escrow, no secure channel and implicit authentication. Until now, there is only one FS-CBS scheme that does not employ the random oracles. Unfortunately, our cryptanalysis indicates that the scheme is subject to the security vulnerability due to the existential forgery attack from the malicious CA. Our attack demonstrates that a CA can destroy its existential unforgeability by implanting trapdoors in system parameters without knowing the target user's secret key. Therefore, it is fair to say that to design a FS-CBS scheme secure against malicious CAs without lying random oracles is still an unsolved issue. To address this problem, we put forward an enhanced FS-CBS scheme without random oracles. Our FS-CBS scheme not only fixes the security weakness in the original scheme, but also significantly optimizes the scheme efficiency. In the standard model, we formally prove its security under the complexity assumption of the square computational Diffie-Hellman problem. In addition, the comparison with the original FS-CBS scheme shows that our scheme offers stronger security guarantee and enjoys better performance.

• 한국통신학회논문지
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• 제29권8C호
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• pp.1203-1209
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• 2004

이동통신 기술과 인터넷 기술을 접목시킨 무선인터넷을 이용한 다양한 서비스가 제공되고 있다. 무선 인터넷 서비스의 경우에도 유선인터넷 환경에서와 같은 보안 알고리즘 및 인증 서비스를 활용한 서비스가 제공되어야 하나 무선 단말기의 제약으로 인해 유선 인터넷 기술을 그대로 적용하는 것은 용이하지 않다. 본 논문에서는 무선 인터넷 환경에서 인증서의 신뢰성을 보장하기 위해서 인증서의 상태를 확인하고 검증하는 방법들을 분석하고, 검증정보를 최소화하고 실시간 검증이 가능한 새로운 인증서 상태 확인 및 검증방법을 제안하였다. 제안한 검증방법은 사용자가 폐지된 인증서를 사용 시 옵저버를 이용하여 핸드셰이크 과정에서 옵저버 정보를 추가하여 전송함으로써 실시간 검증 뿐 아니라 인증서 검증으로 인한 전송시간을 절감할 수 있다.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제10권2호
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• pp.881-896
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• 2016

Certificate-based cryptography is a useful public key cryptographic primitive that combines the merits of traditional public key cryptography and identity-based cryptography. It not only solves the key escrow problem inherent in identity-based cryptography, but also simplifies the cumbersome certificate management problem in traditional public key cryptography. In this paper, by giving a concrete attack, we first show that the certificate-based encryption scheme without bilinear pairings proposed by Yao et al. does not achieve either the chosen-ciphertext security or the weaker chosen-plaintext security. To overcome the security weakness in Yao et al.'s scheme, we propose an enhanced certificate-based encryption scheme that does not use the bilinear pairings. In the random oracle model, we formally prove it to be chosen-ciphertext secure under the computational Diffie-Hellman assumption. The experimental results show that the proposed scheme enjoys obvious advantage in the computation efficiency compared with the previous certificate-based encryption schemes. Without costly pairing operations, it is suitable to be employed on the computation-limited or power-constrained devices.

• 한국통신학회논문지
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• 제29권5C호
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• pp.737-749
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• 2004

분산 네트워크 환경에서 커버로스는 시스템간의 신뢰를 바탕으로 대칭키를 사용하여 사용자를 인증한다. 그러나, 인증(authentication)과 함께 허가(authorization)는 보안의 필수적인 요소다. 본 논문에서는 기존의 커버로스에 프록시 권한 서버(proxy privilege server)를 두고 공개키/개인키를 적용하여 효율적이고 안전한 인증 및 허가 메커니즘을 설계하였다. 제안한 메커니즘에서는 사용자 인증을 위해 미리 정해진 long-term 키와 공개키를 통해 교환한 랜덤 수에 MAC 알고리즘을 적용하여 암호화에 사용하는 세션키 값을 매번 바꾸어주기 때문에 안전성을 높였다. 또한, 전체적인 인증 절차를 간소화하여 사용하는 키의 수를 줄였다. 프록시 권한 서버는 사용자의 권한 요구를 확인하고 권한 속성 인증서(privilege attribute certificate)를 발행한다. 권한 속성 인증서는 사용자의 권한 요구를 응용 서버에 전달하고 권한 위임에 사용된다. 제안한 메커니즘을 사용하여 기존의 커버로스에서 동작하는 효율적이고 안전한 인증 및 허가 알고리즘을 설계한다.

• 인터넷정보학회논문지
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• 제9권4호
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• pp.69-77
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• 2008

X.509 인증서 확장영역에 사용자 MAC 주소를 추가함으로써 더 신뢰성 있는 사용자 인증을 제공한다. 사용자 MAC 주소를 인증서에 첨가해도 통신 퍼포먼스에 영향을 미치지 않는 것을 시연하였으며, 간단한 MAC 주소 첨가로 인해 향상된 사용자 인증을 기대한다.

• 정보보호학회논문지
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• 제16권5호
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• pp.3-13
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• 2006

컴퓨팅 기기들이 점점 산재되고, 기기들의 이동성 또한 증가되면서, 동기적이고 직접적인 점대점 통신 모델은 여러 형태의 분산 컴퓨팅 환경에 적용하기에 적합하지 않다. 이벤트 서비스와 같은 간접통신 모델을 이용하면, 분산 환경에서의 응용들 사이의 결합도를 감소시키고 많은 정적인 요구들을 제거할 수 있는 이점이 있다. 본 논문에서는 신뢰할 수 있는 유비쿼터스 환경을 만들기 위해 Jini 기반의 안전한 이벤트 서비스를 설계하고 구현한다. 구현된 이벤트 서비스는 내용기반의 검색이 가능하고, 정당한 권한을 지닌 제공자와 소비자만이 이벤트를 주고받을 수 있도록 한다. 이벤트 서비스에 인증과 인가기능을 제공하기 위해 SPKI/SDSI 인증서를 이용하고, 이벤트 제공자와 소비자의 분리, 이동기기의 연결 끊김 지원, 내용기반의 검색을 위해 Jini의 자바스페이스를 확장하여 구현한다.