• Proceedings of the CALSEC Conference
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• 2003.09a
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• pp.261-267
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• 2003

This study deals with controversial issues surrounding the today′s cyber-taxation and recommends feasible consumption tax system architecture titled Global Electronic Tax Invoice System (GETI). The GETI is an electronic consumption tax architecture to provide "all-in-one" tax and e-payment services through a trusted third party (TTP). GETI is designed to streamline the overall cyber-taxation process and provide simplified and transparent tax invoice services through an authorized np. To ensure information security, GETI incorporates public Key infrastructure (PKI) based digital certificates and other data encryption schemes when calculating, reporting, paying, and auditing tax in the electronic commerce environment. GETI is based on the OECD cyber-taxation agreement that was reached in January 2001, which established the taxation model for B2B and B2C electronic commerce transactions. For the value added tax systems, tax invoice is indispensable to commerce activities, since they provide documentations to prove the validity of commercial transactions. As paper-based tax invoice systems are gradually phased out and are replaced with electronic tax invoice systems, there is an increasing need to develop a reliable, efficient, transparent, and secured cyber-taxation architecture. To design such architecture, several desirable system attributes were considered -- reliability, efficiency, transparency, and security. GETI was developed with these system attributes in mind.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2002.05a
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• pp.498-501
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• 2002

In the process of Log-In to the system, clear User authentication is the beginning of the information protection service. In the open communication system of today, it is true that a password as security instrument and the inner mechanism of the system and cryptography algorithm for the support of this are also poor. For this reason, this dissertation had a final aim to design the user authentication system, which offer the accuracy and safety. It used RSA and CBC mode of DES as cryptography algorithm and used the Challenge-Response scheme at a authentication protocol and designed the User authentication system to which user access using one time password, output of token to guarantee the safety of the authentication protocol. Alto by using the Public key cryptography algorithm, it could embody the more safe User authentication system.

• Journal of the Optical Society of Korea
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• v.20 no.6
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• pp.722-732
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• 2016

A new optical one-time password (OTP) authentication method using digital holography is proposed, which enhances security strength in the authentication system. A challenge-response optical OTP algorithm based on two-factor authentication is presented using two-step phase-shifting digital holography, and two-way authentication is also performed using challenge-response handshake in both directions. Identification (ID), password (PW), and OTP are encrypted with a shared key by applying phase-shifting digital holography, and these encrypted pieces of information are verified by each party by means of the shared key. The encrypted digital holograms are obtained by Fourier-transform holography and are recorded on a CCD with 256 quantized gray-level intensities. Because the intensity pattern of such an encrypted digital hologram is distributed randomly, it guards against a replay attack and results in higher security level. The proposed method has advantages, in that it does not require a time-synchronized OTP, and can be applied to various authentication applications. Computer experiments show that the proposed method is feasible for high-security OTP authentication.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.31 no.8B
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• pp.730-735
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• 2006

This paper proposes a media key distribution scheme for lawful interception in secured VoIP systems. A problem of the current US or EU standards for lawful interception is that they do not provide a mechanism for collecting keys used for encrypting media streams between two end points. In the proposed scheme, dual encryption was applied on the media keys using two shared secrets: one between the ISP AAA server and user agent, and the other between the TSP registrar and user agent. Only the lawful agency with court warrant can collect both keys from the service providers. This scheme can still provide a privacy by preventing the misusage of the keys by the service providers.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.24 no.6
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• pp.1117-1127
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• 2014

Differential Fault Analysis(DFA) is widely known for one of the most powerful method for analyzing block cipher. it is applicable to block cipher such as DES, AES, ARIA, SEED, and lightweight block cipher such as PRESENT, HIGHT. In this paper, we introduce a differential fault analysis on the lightweight block cipher LEA for the first time. we use 300 chosen fault injection ciphertexts to recover 128-bit master key. As a result of our attack, we found a full master key within an average of 40 minutes on a standard PC environment.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2017.10a
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• pp.575-577
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• 2017

In public key cryptography such as RSA, modular exponentiation is the most time-consuming operation. RSA's modular exponentiation can be computed by repeated modular multiplication. To attain high efficiency for RSA, fast modular multiplication algorithms have been proposed to speed up decryption/encryption. Montgomery multiplication is limited by the carry propagation delay from the addition of long operands. In this paper, we propose a hardware structure that reduces the area of the Montgomery multiplication implementation for lightweight applications of RSA. Experimental results showed that the new design can achieve higher performance and reduce hardware area. A frequency of 884.9MHz and 250MHz were achieved with 84K and 56K gates respectively using the 90nm technology.

• Journal of the Korea Society of Computer and Information
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• v.6 no.4
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• pp.110-118
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• 2001

In this paper we designed the software copyright protection system using encryption technology. Recently most of the softwares have used a password instead of physical devices such as lock key for the software copyright protection. In this case if the password be disclosed. somebody will carl use the software illegally. Therefore if the legal user disclose the password intentionally, somebody will can use more than license numbers. If we use the system suggested in this paper it will not be permitted to use concurrently more than license numbers. As a result nobody can use any softwares illegally. All of the software developers can check a sale amount correctly And the users can get the service of software maintenance quickly.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.15 no.2
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• pp.617-636
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• 2021

This paper presents a privacy-preserving data aggregation scheme deals with the multidimensional data. It is essential that the multidimensional data is rarely mentioned in all researches on smart grid. We use the Paillier Cryptosystem and blinding factor technique to encrypt the multidimensional data as a whole and take advantage of the homomorphic property of the Paillier Cryptosystem to achieve data aggregation. Signature and efficient batch verification have also been applied into our scheme for data integrity and quick verification. And the efficient batch verification only requires 2 pairing operations. Our scheme also supports fault tolerance which means that even some smart meters don't work, our scheme can still work well. In addition, we give two extensions of our scheme. One is that our scheme can be used to compute a fixed user's time-of-use electricity bill. The other is that our scheme is able to effectively and quickly deal with the dynamic user situation. In security analysis, we prove the detailed unforgeability and security of batch verification, and briefly introduce other security features. Performance analysis shows that our scheme has lower computational complexity and communication overhead than existing schemes.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2014.10a
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• pp.285-287
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• 2014

This paper describes a design of area-efficient/low-power cryptographic processor for lightweight block cipher algorithm HIGHT which was approved as a cryptographic standard by KATS and ISO/IEC. The HIGHT algorithm which is suitable for the security of IoT(Internet of Things), encrypts a 64-bit plain text with a 128-bit cipher key to make a 64-bit cipher text, and vice versa. For area-efficient and low-power implementation, we adopt 32-bit data path and optimize round transform block and key scheduler to share hardware resources for encryption and decryption.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.12 no.2
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• pp.147-152
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• 2002

SFLASH, one of the asymmetric signature schemes in NESSIE project, was suggested and accepted in the fat phase. In the latest, results about attacking the affine parts of SFLASH was published. In this paper, we have that an attacker knowing one linear part and two affine parts can easily forge signatures for arbitrary messages without information of the other linear part and the secret suing. It follows that the security of SFLASH depends only on the linear par, which is used in the last step when a signature is being generated. Also, we show that an attacker can obtain partial information of the linear part by the forging method using hem public key and secret elements and we discuss the length of secret key.