• KSII Transactions on Internet and Information Systems (TIIS)
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• 제7권8호
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• pp.2010-2026
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• 2013

The combination of biometrics and cryptography gains a lot of attention from both academic and industry community. The noisy biometric measurement makes traditional identity based cryptosystems unusable. Also the extraction of key from biometric information is difficult. In this paper, we propose an efficient biometric identity based signature scheme (Bio-IBS) that makes use of fuzzy extractor to generate the key from a biometric data of user. The component fuzzy extraction is based on error correction code. We also prove that the security of suggested scheme is reduced to computational Diffie-Hellman (CDH) assumption instead of other strong assumptions. Meanwhile, the comparison with existing schemes shows that efficiency of the system is enhanced.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제7권11호
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• pp.2928-2940
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• 2013

Key exposure is a major threat to secure cryptosystems. To mitigate the impact caused by key-compromise attacks, a key-insulated cryptographic mechanism is a better alternative. For securing the large message communication in peer-to-peer networks, in this paper, we propose the first novel identity-based key-insulated encryption (IB-KIE) scheme with message linkages. Our scheme has the properties of unbounded time periods and random-access key-updates. In the proposed scheme, each client can periodically update his private key while the corresponding public one remains unchanged. The essential security assumption of our proposed scheme is based on the well-known bilinear Diffie-Hellman problem (BDHP). To ensure the practical feasibility, we also formally prove that the proposed scheme achieves the security requirement of confidentiality against indistinguishability under adaptive chosen-ciphertext attacks (IND-CCA2) in the random oracle model.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제5권12호
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• pp.2392-2402
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• 2011

In order to protect some important information communicated through an insecure network, a common hidden key must be used. One can produce the common hidden key using key agreement protocols; and this helps to have high security in modern data networks. Today, the designers of public key cryptography protocols try to set the public identity of a system's users (like their email addresses) as their public key. This not only makes a cryptographic protocol more efficient but also decreases its cost. These protocols are called "identity-based". In this article, an identity-based multiple key agreement scheme will be presented; this scheme uses the challenge-response method to do the verification. While the number of random values produced in our scheme is the same as other schemes, the number of keys generated in this scheme is much more than what many other key agreement schemes produce,. Therefore, we will have less computational complexities campered with other schems. In this paper, we consider the security of our scheme and consequently, we will show that it satisfies many security conditions such as strong security.

• 정보보호학회논문지
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• 제1권1호
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• pp.3-15
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• 1991

shamir는 공개키 저장을 위한 키 디렉토리(Key directory)의 유지가 요구되지 않는 ID(Identity)기본 암호 시스팀 및 디지틀 서명 방식의 개념을 1984년 제안하였다. 본 논문에서는 지금까지 발표된 대표적인 공개키 암호알고리즘(RSA, Merkle-Hellman, El-Gamal 암호알고리즘) 등을 바탕으로 이 산대수문제에 기반을 둔 ID기본 디지틀 서명방식을 제안하고 이에 대한 가능한 여러 공격 형태들을 분석함으로서 안전성(security)을 입증한다. 그리고 ID 기본 암호시스팀과 디지틀 서명방식의 특징을 제시한다.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제11권4호
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• pp.2254-2275
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• 2017

In this paper, we present an IND-CCA2 secure certificateless proxy re-encryption scheme in the random oracle model. A certificateless public key cryptography simplifies the certificate management in a traditional public key infrastructure and the built-in key escrow feature in an identity-based public key cryptography. Our scheme shares the merits of certificateless public key encryption cryptosystems and proxy re-encryption cryptosystems. Our certificateless proxy re-encryption scheme has several practical and useful properties - namely, multi-use, unidirectionality, non-interactivity, non-transitivity and so on. The security of our scheme bases on the standard bilinear Diffie-Hellman and the decisional Bilinear Diffie-Hellman assumptions.

• 정보보호학회지
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• 제4권1호
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• pp.20-29
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• 1994

Shamir가1984년 개인정보(ID)를 이용한 암호시스템의 개념을 제안한 이래 Fiat-Shamir방식을 필두로 하여 Ohta, Guillou 등이 개인정보에 기반을 둔 서명법과 영지식 대화형 증명방식을 조합한 각종 개인식별 방식 및 디지탈 서명 방식들이 제안되어 왔다. 또한, Okamoto 등이 개인 정보를 이용한 키분배 방식을 제안하였다. 본고에서는 지금까지 제안된 개인정보를 이용한 암호시스템의 대표적인 방식들에 대해 그들의 특징과 장단점을 비교 분석하였다.

• ETRI Journal
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• 제38권4호
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• pp.724-734
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• 2016

To achieve confidentiality, integrity, authentication, and non-repudiation simultaneously, the concept of signcryption was introduced by combining encryption and a signature in a single scheme. Certificate-based encryption schemes are designed to resolve the key escrow problem of identity-based encryption, as well as to simplify the certificate management problem in traditional public key cryptosystems. In this paper, we propose a new certificate-based signcryption scheme that has been proved to be secure against adaptive chosen ciphertext attacks and existentially unforgeable against chosen-message attacks in the random oracle model. Our scheme is not based on pairing and thus is efficient and practical. Furthermore, it allows a signcrypted message to be immediately verified by the public key of the sender. This means that verification and decryption of the signcrypted message are decoupled. To the best of our knowledge, this is the first signcryption scheme without pairing to have this feature.

• 정보보호학회논문지
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• 제19권6호
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• pp.17-22
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• 2009

인증서 없는 공개키 시스템은 기존의 공개키 암호시스템에서 인증서의 필요성을 제거하고 신원 기반 암호시스템에서 키 위탁 문제를 해결하였다. 본 논문에서는 Guo 등과 Wang 등에 의해서 제안된 각각의 인증서 없는 서명 기법들이 공격자 종류 I에 의해 키 대치공격에 취약하다는 것을 보인다. 다시 말해, 서명자의 공개키를 대치할 수 있는 능력을 가진 공격자가 서명자의 비밀키를 알지 못함에도 불구하고 서명을 위조할 수 있음을 보이고 이러한 공격을 방지하기 위한 대응법을 제안한다.