• Journal of the Korea Institute of Information Security & Cryptology
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• v.14 no.1
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• pp.59-69
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• 2004

Password-based authenticated group key exchange protocols provide a group of user, communicating over a public(insecure) channel and holding a common human-memorable password, with a session key to be used to construct secure multicast sessions for data integrity and confidentiality. In this paper, we present a password-based authenticated group key exchange protocol and prove the security in the random oracle model and the ideal cipher model under the intractability of the decisional Diffie-Hellman(DH) problem and computational DH problem. The protocol is scalable, i.e. constant round and with O(1) exponentiations per user, and provides forward secrecy.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.10 no.1
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• pp.84-90
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• 2011

In this paper, a VoIP-based voice secure telecommunication technology using the text-independent speaker authentication in the telematics environments is proposed. For the secure telecommunication, the sender's voice packets are encrypted by the public-key generated from the speaker's voice information and submitted to the receiver. It is constructed to resist against the man-in-the middle attack. At the receiver side, voice features extracted from the received voice packets are compared with the reference voice-key received from the sender side for the speaker authentication. To improve the accuracy of text-independent speaker authentication, Gaussian Mixture Model(GMM)-supervectors are applied to Support Vector Machine (SVM) kernel using Bayesian information criterion (BIC) and Mahalanobis distance (MD).

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.45 no.10
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• pp.40-48
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• 2008

Security of self organized mobile ad hoc networks is an important issue because administration information in the networks is managed by the constituent nodes. Especially authentication mechanism is necessary for trust setup between newly joining nodes and the network. The authentication models and protocols which are based on the wireline infrastructure could not be practical for mobile ad hoc network. Although public key algorithm-based method is widely used for authentication, it is not easy to be applied to mobile ad hoc networks because they do not have infrastructure such as centralized CA which is needed for certificate verification. In this paper, we consider the public key based random CA group method proposed in [1] to provide efficient authentication scheme to mobile ad hoc networks and analyze the performance of the method, which is then compared to the home CA method. From the analysis results, we see that the random CA method where the function of CA is distributed to some mobile nodes and the authentication information is propagated to randomly chosen CAs shows higher reliability and lower cost than home CA method.

• The Journal of the Korea Contents Association
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• v.16 no.8
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• pp.90-96
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• 2016

The 3390 million people, around 83% of the adult population in Korea use smartphone. Although the safety problem of the certificate has been occurred continuously, most of these users use the certificate. These safety issues as a solution to 'The owner of a mobile phone using SMS authentication technology', 'Biometric authentication', etc are being proposed. but, a secure and reliable authentication scheme has not been proposed for replace the certificate yet. and there are many attacks to steal the certificate and private key. For these reasons, security experts recommend to store the certificate and private key on usb flash drive, security tokens, smartphone. but smartphones are easily infected malware, an attacker can steal certificate and private key by malicious code. If an attacker snatchs the certificate, the private key file, and the password for the private key password, he can always act as valid user. In this paper, we proposed a safe way to keep the private key on smartphone using smartphone's unique information and user password. If an attacker knows the user password, the certificate and the private key, he can not know the smart phone's unique information, so it is impossible to use the encrypted private key. Therefore smartphone user use IT service safely.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2009.05a
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• pp.781-784
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• 2009

IPTV, which is convergence of Communication and Broadcasting, has improved quickly recently. This service can provide high quality and various services to their customers, such as choosing channels freely, VOD and many kinds of Interactive service. As the technology of IPTV rapid development, more and more people worry about its disadvantages during the spread and apply, for instance, the illegal application, illegal copy, access authority abuse and the danger of the IPTV contents. This paper will provide the solution to solve these problems, through the Public Key Certificate of PKI(Public Key Infrastructure) and the Attribute Certificate of PMI(Privilege Management Infrastructure).

• The Transactions of the Korea Information Processing Society
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• v.6 no.1
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• pp.122-133
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• 1999

Uses can share information and use resources effectively by using TCP/IP-based networks. So, a protocol to manage complex networks effectively is needed. For the management of the distributed networks, the SNMP(Simple Network Management Protocol) has been adopted as an international standard in 1989, and the SNMPv2 in which a security function was added was published in 1993. There are two encryption schemes in SNMPv2, the one is a DES using symmetric encryption scheme and the other is a MD5(Message Digest5) hash function for authentication. But the DES has demerits that a key length is a few short and the encryption and the authentication is executed respectively. In order to solve these problems, wer use a RSA cryptography in this paper. In this paper, we examine the items related with SNMP. In addition to DES and MD5 propose in SNMPv3, we chance security functionality by adopting RSA, a public key algorithm executing the encryption and the authentication simultaneously. The proposed SNMPv3 security module is written in JAVA under Windows NT environment.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.38C no.7
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• pp.595-604
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• 2013

Devising a secure authenticated key agreement (AKA) protocol for two entities communicating over an open network is a matter of current research. McCullagh et al. proposed a new two-party identity-based AKA protocol supporting both key escrow and key escrow-less property instantiated by either in a single domain or over two distinct domains. In this paper, we show that their protocol over two distinct domains suffers from masquerading attack and therefore does not satisfy the claimed security. The attack is made possible due to the lack of sufficient authentication of entity and integrity assurance in the protocol. We then propose an efficient verifiable key agreement protocol by including signature primitive in the authentication procedure to solve the problem of McCullagh et al.'s protocol.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.29 no.2C
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• pp.348-353
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• 2004

Development of an efficient and secure payment system is prerequisite for the construction of electronic payment mechanism in mobile environment. Since current PayWord protocol system generates vendor's certificate for each transaction, it requires lot of operation for transaction. In this paper, we use a session key generated by ID-based tripartite Key agreement protocol which use an Elliptic Curve Cryptosystem over finite field $F_{q}$ for transactions. Therefore, our protocol reduces algorithm operations. In particular, proposed protocol using ID-based public key cryptosystem has the advantages over the existing systems in speed and it is more secure in Man-in-the-middle attacks and Forward secrecy.

• Journal of Korea Multimedia Society
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• v.10 no.3
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• pp.373-380
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• 2007

In this paper we propose a new efficient authentication protocol that reduces overheads of computation for digital signature generation/verification on mobile devices in the Personal Area Network (PAN). In particular, we focus on eliminating the traditional public key operations on mobile devices without any assistance of a signature server. Moreover, the proposed protocol provides a simplified procedure for certificate status management to alleviate communication and computational costs on mobile devices in the PAN.

• Journal of KIISE:Information Networking
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• v.33 no.2
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• pp.131-138
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• 2006

To achieve security in wireless sensor networks(WSN), it is important to be able to encrypt and authenticate messages sent among sensor nodes. Due to resource constraints, many key agreement schemes used in general networks such as Diffie-Hellman and public-key based schemes are not suitable for wireless sensor networks. The current pre-distribution of secret keys uses q-composite random key and it randomly allocates keys. But there exists high probability not to be public-key among sensor nodes and it is not efficient to find public-key because of the problem for time and energy consumption. To remove problems in pre-distribution of secret keys, we propose a new cryptographic key management protocol, which is based on the clustering scheme but does not depend on probabilistic key. The protocol can increase efficiency to manage keys because, before distributing keys in bootstrap, using public-key shared among nodes can remove processes to send or to receive key among sensors. Also, to find outcompromised nodes safely on network, it selves safety problem by applying a function of lightweight attack-detection mechanism.