• Proceedings of the Korea Institutes of Information Security and Cryptology Conference
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• 2006.06a
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• pp.677-680
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• 2006

신뢰할 수 없는 저장매체에 데이터를 안전하게 보관하기 위해서 대부분의 시스템은 데이터를 암호화하는 방식을 사용한다. 암호화된 데이터를 통해서는 원래의 평문에 어떠한 내용이 포함되어 있는지 알 수가 없으며, 해당 데이터의 내용을 열람하기 위해서는 암호화된 데이터 전체를 복호화해야만 한다. 본 논문에서는 암호화된 데이터에 대해 키워드 검색이 가능한 프로토콜을 제안하여, 데이터 전체를 복호화하지 않고 특정 키워드의 포함 여부를 판단할 수 있도록 하였다.

• Proceedings of the Korea Institutes of Information Security and Cryptology Conference
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• 2003.07a
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• pp.67-70
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• 2003

인터넷과 같은 네트워크와 컴퓨터 이용자의 급격한 증가로 인해 컨텐츠 유출 사고 및 개인 정보유출 사고가 빈번하게 발생되고 있다. 이러한 문제를 해결하기 위한 방법 중의 하나가 컨텐츠를 암호화하는 방법이다. 그러나 이 또한 최근에 암호화의 안전성에 많은 문제점을 안고 있다. 이에 렬 논문에서는 비밀키 암호화 방식의 대표인 DES의 문제점에 대해서 분석하고 차세대 암호표준으로 선정한 대칭형 암호알고리즘인 Rijndael을 이용해서 파일의 암호화를 구현하고자 한다.

• Proceedings of the KAIS Fall Conference
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• 2009.05a
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• pp.158-161
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• 2009

최근 개인정보유출사건으로 프라이버시에 대한 관심이 급증하면서, 데이터베이스의 내용을 암호화할 필요성이 요구된다. 초기에는 문서 전체의 복호화를 통해서만 검색이 가능하기 때문에 효율성이 떨어져 암호화기법이 거의 사용되지 않았다. 최근에는 복호화 하지 않고 암호화된 데이터로부터 특정 키워드를 포함하는 정보를 효율적으로 검색하고자 하는 연구가 시작되었다. Song의 연구를 시작으로 점차 효율적인 검색 기법이 제안되어졌다. 본 논문에서는 데이터베이스내의 암호화된 데이터를 검색하는 기법에 대한 설계 및 구현하고, 그에 따른 정확도 및 오류율을 분석한다.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.21 no.11
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• pp.878-883
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• 2020

Cryptographic algorithms are used to prevent the illegal manipulation of data. They are divided into public-key cryptosystems and symmetric-key cryptosystems. Public-key cryptosystems require considerable time for encryption and decryption compared to symmetric-key cryptosystem. On the other hand, key management, and delivery are easier for public-key cryptosystems than symmetric-key cryptosystems because different keys are used for encryption and decryption. Furthermore, hash functions are being used very effectively to verify the integrity of the digital content, as they always generate output with a fixed size using the data of various sizes as input. This paper proposes a method using RSA public-key cryptography and a hash function to determine if a digital image is deformed or not and to detect the manipulated location. In the proposed method, the entire image is divided into several blocks, 64×64 in size. The watermark is then allocated to each block to verify the deformation of the data. When deformation occurs, the manipulated pixel will be divided into smaller 4×4 sub-blocks, and each block will have a watermark to detect the location. The safety of the proposed method depends on the security of the cryptographic algorithm and the hash function.

• Journal of the Korea Society of Computer and Information
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• v.25 no.1
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• pp.87-92
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• 2020

Various devices, which are powerful computer and low-performance sensors, is connected to IoT network. Accordingly, applying mutual authentication for devices and data encryption method are essential since illegal attacks are existing on the network. But cryptographic methods such as symmetric key and public key algorithms, hash function are not appropriate to low-performance devices. Therefore, this paper proposes blockchain-based lightweight IoT mutual authentication protocol for the low-performance devices.

• Proceedings of the Korea Information Processing Society Conference
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• 2012.04a
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• pp.676-679
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• 2012

지능형 전력망인 AMI(Advanced Metering Infrastructure)에 대한 관심이 높아지고 있다. AMI 시스템은 전력의 제공자와 소비자가 양방향 통신을 함으로써 전력의 효율적인 관리를 위한 것이지만 기존의 전력망에 통신망인 IT의 결합으로 인한 보안 문제에 대한 대응방안이 필요하다. 본 논문에서는 한전 KDN(주)가 규정하여 추진하고 있는 AMI 시스템의 문제점을 분석하고, 한전의 규정상에서 적용 가능한 대칭키 기반의 보안으로 안전한 AMI 시스템의 통신망 구조를 제시하여 암호화 및 메시지인증을 통해 기밀성, 무결성, 가용성 등의 보안 요건을 만족시킬 수 있는 통합적인 관리를 제안한다.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.12 no.6
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• pp.71-80
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• 2002

To provide the confidentiality of messages transmitted over the network, the use of cryptographic system is increasing gradually and the hybrid cryptosystem, which combines the advantages of the symmetric cryptosystem and the public key cryptosystem is widely used. In this paper, we proposes a new hybrid cryptosystem capable of providing implicit authentication for the sender of the ciphertext by means of the 1-pass key distribution protocol that offers implicit key authentication, hash function and symmetric cryptosystem. Also, we describe some examples such as the Diffie-Hellman based system and the Nyberg-Ruppel based system. The proposed hybrid cryptosystem is an efficient more than general public key cryptosystems in the aspect of computation work and provides implicit authentication for the sender without additional increase of the communication overhead.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.20 no.4
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• pp.786-792
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• 2016

Camellia was jointly developed by Nippon Telegraph and Telephone Corporation and Mitsubishi Electric Corporation in 2000. Camellia specifies the 128-bit message block size and 128-, 192-, and 256-bit key sizes. In this paper, a modified round operation block which unifies a register setting for key schedule and a conventional round operation block is proposed. 16 ROMs needed for key generation and round operation are implemented using only 4 dual-port ROMs. Due to the use of a message buffer, encryption/decryption can be executed without a waiting time immediately after KA and KB are calculated. The suggested block cipher Camellia algorithm is designed using Verilog-HDL, implemented on Virtex4 device and operates at 184.898MHz. The designed cryptographic core has a maximum throughput of 1.183Gbps in 128-bit key mode and that of 876.5Mbps in 192 and 256-bit key modes. The cryptographic core of this paper is applicable to security module of the areas such as smart card, internet banking, e-commerce and satellite broadcasting.

• Journal of the Korea Society of Computer and Information
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• v.3 no.4
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• pp.91-96
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• 1998

In this paper we designed a secure client-server system to be able to protect messages between client and server using cryptography We authenticated each other using a asymmetric encryption algorithm on the logon procedure and minimized the time to encrypt and decrypt messages using a symmetric encryption algorithm on exchanging messages. We proved that it is possible to make a digital signature on our secure client-server system. And we suggested the efficient key management method to generate and distribute cryptograpic key securely.

• Journal of Korea Multimedia Society
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• v.6 no.2
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• pp.288-300
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• 2003

As the importance of information security gets recognized seriously, ciphers technology gets used more. Particularly, since public key ciphers are easier to control the key than symmetric key ciphers and also digital signature is easily implemented, public key ciphers are increased used. Nowadays, public key infrastructure is established and operated to use efficiently and securely the public key ciphers. In the public key infrastructure, the user registers at the certificate authority to generate the private key and public key pair and the certificate authority issues the certificate on the public key generated. Through this certificate, key establishment between users is implemented and encryption communication becomes possible. But, control function of session key established in the public key infrastructure is not provided. In this thesis, the certificate issuing protocol to support the key recovery of the session key established during the wireless authentication and key establishment is proposed.