• KSII Transactions on Internet and Information Systems (TIIS)
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• v.11 no.11
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• pp.5625-5641
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• 2017

Certificateless public key cryptography resolves the certificate management problem in traditional public key cryptography and the key escrow problem in identity-based cryptography. In recent years, some good results have been achieved in speeding up the computation of bilinear pairing. However, the computation cost of the pairing is much higher than that of the scalar multiplication over the elliptic curve group. Therefore, it is still significant to design cryptosystem without pairing operations. A multi-signer universal designated multi-verifier signature scheme allows a set of signers to cooperatively generate a public verifiable signature, the signature holder then can propose a new signature such that only the designated set of verifiers can verify it. Multi-signer universal designated multi-verifier signatures are suitable in many different practical applications such as electronic tenders, electronic voting and electronic auctions. In this paper, we propose a certificateless multi-signer universal designated multi-verifier signature scheme and prove the security in the random oracle model. Our scheme does not use pairing operation. To the best of our knowledge, our scheme is the first certificateless multi-signer universal designated multi-verifier signature scheme.

• The Journal of the Korea Contents Association
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• v.5 no.3
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• pp.9-17
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• 2005

Recently, there are rapid development of information and communication technology and rapid growing of e-business users. We propose a method for security problem on the internet environment which changes from wire internet to wireless internet or wire/ wireless internet. Wireless e-business adopts credit card WPP protocol and AIP protocol proposed by ASPeCT. WAP, one of the protocol used by WPP has weakness of leaking out information from WG which connected wire and wireless communication. Certification chain based AIP protocol requires a lot of computation time and user IDs are known to others. We propose a Micro-Payment protocol based on credit card. Our protocol use the encryption techniques of the public key with ID to ensure the secret of transaction in the step of session key generation. IDs are generated using ECC based Weil pairing. We also use the certification with hidden electronic sign to transmit the payment result. The proposed protocol also solves the privacy protection and Non-repudiation problem.

• Journal of Internet Computing and Services
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• v.13 no.2
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• pp.59-71
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• 2012

PKI-based public key scheme is outstanding in terms of authenticity and privacy. Nevertheless its application brings big burden due to the certificate/key management. It is difficult to apply it to limited computing devices in WSN because of its high encryption complexity. The Bilinear Pairing emerged from the original IBE to eliminate the certificate, is a future significant cryptosystem as based on the DDH(Decisional DH) algorithm which is significant in terms of computation and secure enough for authentication, as well as secure and faster. The practical EC Weil Pairing presents that its encryption algorithm is simple and it satisfies IND/NM security constraints against CCA. The Random Oracle Model based IBE PKG is appropriate to the structure of our target system with one secret file server in the operational perspective. Our work proposes modification of the Weil Pairing as proper to the closed network for secret file distribution[2]. First we proposed the improved one computing both encryption and message/user authentication as fast as O(DES) level, in which our scheme satisfies privacy, authenticity and integrity. Secondly as using the public key ID as effective as PKI, our improved IBE variant reduces the key exposure risk.

• ETRI Journal
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• v.40 no.2
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• pp.207-217
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• 2018

As implementation of the in-band full duplex (IFD) transceiver becomes feasible, research interest is growing with respect to using IFD communication with cellular networks. However, the cellular network in which the IFD communication is applied inevitably suffers from an increase of the co-channel interference (CCI) due to IFD simultaneous transmission and reception. In this paper, we analyze the performance of a cellular network based on uni-directional IFD (UD-IFD) communication, wherein an IFD base station simultaneously supports downlink and uplink transmissions of half-duplex (HD) users. In addition, a multi-pair CCI cancellation (MP-CCIC) method combining CCIC and user pairing is proposed to improve the performance of the UD-IFD network. Simulation results showed that, compared to a conventional HD cellular network without using CCIC, capacity gain was not obtained in the UD-IFD cellular network. On the other hand, when applying the proposed MP-CCIC, the capacity of the UD-IFD cellular network greatly improved compared to that of an HD cellular network.

• Journal of KIISE:Information Networking
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• v.30 no.6
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• pp.720-728
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• 2003

Blind signature is such a signature scheme that conceals the contents of signature itself and who is the user of the signature make user's anonymity possible. For this reason, they are used in security services such as electronic cashes and electronic votes in which the behavior of actor should not be exposed. In this paper we propose an ID-based blind signature scheme from Gap Diffie-Hellman group. Its security is based on the hardness of Computational Diffie-Hellman Problem. Proposed scheme efficiently improve against existing blind signature scheme by using two-pass protocol between two users and by reducing computation process. Therefore it can be used efficiently in wireless PKI environment.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.36 no.6A
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• pp.601-608
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• 2011

In OFDMA(Orthogonal Frequency Division Multiple Access) based multi-hop networks, the subcarrier-pairing scheme using the SNR(Signal-to-Noise Ratio) has been proposed as the best solution. But, this scheme is not optimal in cognitive radio system, because of the power control due to the interference to the primary user. In this paper, we propose two subcarrier-pairing schemes for OFDMA based 2-hop cognitive radio systems. One is the IT(Interference channel gain) scheme considering only the interference channel gain, and the other is the CI(Channel SNR over interference channel gain) scheme considering the ratio of channel SNR to interference channel gain. The results show that the CI scheme has the best performance in which throughput is improved more than 10% in comparison with other schemes.

• Journal of Information Processing Systems
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• v.10 no.1
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• pp.92-102
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• 2014

In recent years, there has been growing interest in secure pairing, which refers to the establishment of a secure communication channel between two mobile devices. There are a number of descriptions of the various types of out-of-band (OOB) channels, through which authentication data can be transferred under a user's control and involvement. However, none have become widely used due to their lack of adaptability to the variety of mobile devices. In this paper, we introduce a new OOB channel, which uses accelerometer-based gesture input. The gesture-based OOB channel is suitable for all kinds of mobile devices, including input/output constraint devices, as the accelerometer is small and incurs only a small computational overhead. We implemented and evaluated the channel using an Apple iPhone handset. The results demonstrate that the channel is viable with completion times and error rates that are comparable with other OOB channels.

• ETRI Journal
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• v.42 no.6
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• pp.846-858
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• 2020

The non-orthogonal multiple access (NOMA) technique offers throughput improvement to meet the demands of the future generation of wireless communication networks. The objective of this work is to further improve the throughput by including an underlay cognitive radio network with an existing multi-carrier NOMA network, using cooperative communication. The throughput is maximized by optimal resource allocation, namely, power allocation, subcarrier assignment, relay selection, user pairing, and subcarrier pairing. Optimal power allocation to the primary and secondary users is accomplished in a way that target rate constraints of the primary users are not affected. The throughput maximization is a combinatorial optimization problem, and the computational complexity increases as the number of users and/or subcarriers in the network increases. To this end, to reduce the computational complexity, a dynamic network resource allocation algorithm is proposed for combinatorial optimization. The simulation results show that the proposed network improves the throughput.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.18 no.5
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• pp.195-199
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• 2008

We present an attack which forges a credential without the help of the credential issuer in the protocol designed by Nakazato, Wang and Yamamura at ASIAN 2007 The attack avoids using the credential issuer's private key by taking advantage of the property of bilinear pairing. Implication of this collusion attack by user and verifiers also discussed.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.9 no.10
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• pp.3831-3851
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• 2015

This paper is concerned with the problem of joint resource allocation and user-pairing in virtual MIMO SC-FDMA systems to improve service quality of experience (QoE). No-reference logarithmic model is introduced to quantify service experience for each user and the objective is to maximize sum of all user's mean of score (MOS). We firstly formulate the optimal problem into an S-dimensional (S-D) assignment problem. Then, to solve this problem, the modified Lagrangian relaxation algorithm is deduced to obtain the suboptimal result of joint user-paring and subchannel allocation. The merits of this solution are as follows. First, the gap between its results and the global optimal one can be quantified and controlled by balancing the complexity and accuracy, which merit the other suboptimal algorithms do not have. Secondly, it has the polynomial computational complexity and the worst case complexity is O(3LN³), where L is the maximum iteration time and N is the number of subchannels. Simulations also prove that our proposed algorithm can effectively improve quality of experience and the gap between our proposed and the optimal algorithms can be controlled below 8%.