• Journal of the Korea Institute of Information and Communication Engineering
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• v.11 no.8
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• pp.1519-1527
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• 2007

In order to combat the security threats that sensor networks are exposed to, a cryptography protocol is implemented at sensor nodes for point-to-point encryption between nodes. Given that nodes have limited resources, symmetric cryptography that is proven to be efficient for low power devices is implemented. Data protection is integrated into a sensor's packet by the means of symmetric encryption with the Dragon stream cipher and incorporating the newly designed Dragon-MAC Message Authentication Code. The proposed algorithm was designed to employ some of the data already computed by the underlying Dragon stream cipher for the purpose of minimizing the computational cost of the operations required by the MAC algorithm. In view that Dragon is a word based stream cipher with a fast key stream generation, it is very suitable for a constrained environment. Our protocol regarded the entity authentication and message authentication through the implementation of authenticated encryption scheme in wireless sensor nodes.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.28 no.6
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• pp.1401-1414
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• 2018

The k-means clustering algorithm groups input data with the number of groups represented by variable k. In fact, this algorithm is particularly useful in market segmentation and medical research, suggesting its wide applicability. In this paper, we propose a privacy-preserving clustering algorithm that is appropriate for outsourced encrypted data, while exposing no information about the input data itself. Notably, our proposed model facilitates encryption of all data, which is a large advantage over existing privacy-preserving clustering algorithms which rely on multi-party computation over plaintext data stored on several servers. Our approach compares homomorphically encrypted ciphertexts to measure the distance between input data. Finally, we theoretically prove that our scheme guarantees the security of input data during computation, and also evaluate our communication and computation complexity in detail.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2019.05a
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• pp.251-253
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• 2019

This paper describes an implementation of a security SoC (System-on-Chip) prototype that interfaces a microprocessor with a block cipher crypto-core. The Cortex-M0 was used as a microprocessor, and a crypto-core implemented by integrating ARIA and AES into a single hardware was used as an intellectual property (IP). The integrated ARIA-AES crypto-core supports five modes of operation including ECB, CBC, CFB, CTR and OFB, and two master key sizes of 128-bit and 256-bit. The integrated ARIA-AES crypto-core was interfaced to work with the AHB-light bus protocol of Cortex-M0, and the crypto-core IP was expected to operate at clock frequencies up to 50 MHz. The security SoC prototype was verified by BFM simulation, and then hardware-software co-verification was carried out with FPGA implementation.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.17 no.3
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• pp.27-33
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• 2007

Recently, a new hard problem on a two dimensional vector space called vector decomposition problem (VDP) was proposed by M. Yoshida et al. and proved that it is at least as hard as the computational Diffe-Hellman problem (CDHP) on a one dimensional subspace under certain conditions. However, in this paper we present the VDP relative to a specific basis can be solved in polynomial time although the conditions proposed by M. Yoshida on the vector space are satisfied. We also suggest strong instances based on a certain type basis which make the VDP difficult for any random vector relative to the basis. Therefore, we need to choose the basis carefully so that the VDP can serve as the underlying intractable problem in the cryptographic protocols.

• The KIPS Transactions:PartC
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• v.11C no.4
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• pp.439-446
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• 2004

In the Internet, user authentication is the most important service in secure communications. Although password-based mechanism is the most widely used method of the user authentication in the network, people are used to choose easy-to-remember passwords, and thus suffers from some Innate weaknesses. Therefore, using a memorable password it vulnerable to the dictionary attacks. The techniques used to prevent dictionary attacks bring about a heavy computational workload. In this paper, we describe a recent solution, the Optimal Strong-Password Authentication (OSPA) protocol, and that it is vulnerable to the stolen-verifier attack and an impersonation attack. Then, we propose an Improved Optimal Strong-Password Authentication (I-OSPA) protocol, which is secure against stolen-verifier attack and impersonation attack. Also, since the cryptographic operations are computed by the processor in the smart card, the proposed I-OSPA needs relatively low computational workload and communicational workload for user.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.26 no.1
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• pp.69-79
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• 2016

Biometric authentication is considered as being an efficient authentication method, since a user is not required to possess or memorize any other information other than biometrics. However, since biometric information is sensitive and could be permanently unavailable in case of revealing that information just once, it is essential to preserve privacy of biometrics. In addition, since noise is inherent in the user of biometric recognition technologies, the biometric authentication needs to handle the noise. Recently, biometric authentication protocols using fuzzy extractor have been actively researched, but the fuzzy extractor-based authentication has a problem that a user should memorize an additional information, called helper data, to deal with their noisy biometric information. In this paper, we propose a novel biometric authentication protocol using Hidden Vector Key Encapsulation Mechanism(HV-KEM) which is one of functional encryption schemes. A primary advantage of our protocol is that a user does not need to possess or memorize any additional information. We propose security requirements of HV-KEM necessary for constructing biometric authentication protocols, and analyze our proposed protocol in terms of correctness, security, and efficiency.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.28 no.5
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• pp.1035-1045
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• 2018

Recently, with the development of IT technology, authentication methods of users using cloud services have been diversified. However, research on providing authentication information of a user using a cloud service securely according to authority has not been make until now. In this paper, we propose a key establishment protocol which can perform split authentication using secret key and access control key according to the role authority of user in Intra cloud environment. The proposed protocol generates the access control key and secret key of the user by using the attributes of the user and the generated random number($t_1$, $t_2$), and classifies the roles according to the user's authority after generating the key. Unnecessary operation processes can be reduced. As a result of the performance evaluation, the proposed protocol guarantees the security against various type of attacks that may occur in the cloud environment because the user is authenticated by dividing the access control key and secret key. The size of the ciphertext used to establish the key could be reduced by ${\sum}+1$ more than the existing protocol.

• Journal of Convergence for Information Technology
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• v.7 no.3
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• pp.91-96
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• 2017

IoT which is an abbreviation of Internet of Things refers to the communication network service among various objects such as people-people, objects-objects interconnection. The characteristic of IoT that enables direct connection among each device makes security to be considered as more emphasized factor. Though a security module such as an authentication protocol for resolving various security problems that may occur in the IoT environment has been developed, some weak points in security are still being revealed. Therefore, this paper proposes a method for including a protocol including gateway authentication procedure and mutual authentication between the devices and gateways. Protocols with additional authentication procedures can appropriately respond to attackers' spoofing attacks. In addition, important information in the message used for authentication process is protected by encryption or hash function so that it can respond to wiretapping attacks.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.11 no.5
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• pp.53-62
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• 2001

Fast diffusion of personal computer and network, and developed security technology are augmenting specific gravity of convenient and safe electronic voting system supplementing much problems of existent off-line vote form. But in spite of enlargement of these weight, much limitations are extravagant. Specially, problem that secure voter\`s anonymousness and accuracy of poll can be important urea that judge if electronic voting system can be applied actually. Also, problems such as buying and selling of vote remain to subject that must solve yet. In this paper, we introduce items that is considered to design the safe electronic voting system, and present limitation of electronic polling system announced in [1]. And we propose improvement way. Improved protocol keeping advantages that is presented in [1], designed to keep away voter\`s anonymousness defamation by conspiracy of Election Administration Committee and Totaling Committee, and block unlawful election intervention as original.

• Journal of KIISE:Computer Systems and Theory
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• v.29 no.3
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• pp.153-160
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• 2002

In this paper, we consider a secure and efficient metering scheme to measure the interaction between clients and servers in interned advertising. In most cases internet advertising is composed of clients, servers, and an audit agency who collects a metering information about the number of clients that were served by each server. The metering scheme should always be secure against fraud attempts by servers which maliciously try to inflate the number of their clients and against clients that attempt to disrupt the metering process. So we suggest secure and efficient metering schemes, based on some cryptographic techniques, which are also very accurate and robust.