• The KIPS Transactions:PartC
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• v.14C no.3 s.113
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• pp.239-254
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• 2007

Ubiquitous computing supports environment to freely connect to network without restrictions of place and time. This environment enables easy access and sharing of information, but because of easy unauthorized accesses, specified security policy is needed. Especially, ubiquitous sensor network devices use limited power and are small in size, so, many restrictions on policies are bound to happen. This paper proposes double-key based light weight security protocol, independent to specific sensor OS, platform and routing protocol in ubiquitous sensor network. The proposed protocol supports safe symmetric key distribution, and allows security manager to change and manage security levels and keys. This had a strong merit by which small process can make large security measures. In the performance evaluation, the proposed light weight security protocol using double-key in ubiquitous sensor network allows relatively efficient low power security policy. It will be efficient to ubiquitous sensor network, such as smart of ace and smart home.

• Journal of the Optical Society of Korea
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• v.18 no.5
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• pp.477-484
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• 2014

In this paper, we propose a new optical secret key sharing method based on the Diffie-Hellman key exchange protocol required in cipher system. The proposed method is optically implemented by using a free-space interconnected optical logic gate technique in order to process XOR logic operations in parallel. Also, we present a compact type of optical module which can perform the modified Diffie-Hellman key exchange for a cryptographic system. Schematically, the proposed optical configuration has an advantage of producing an open public key and a shared secret key simultaneously. Another advantage is that our proposed key exchange system uses a similarity to double key encryption techniques to enhance security strength. This can provide a higher security cryptosystem than the conventional Diffie-Hellman key exchange protocol due to the complexity of the shared secret key. Results of numerical simulation are presented to verify the proposed method and show the effectiveness in the modified Diffie-Hellman key exchange system.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.13 no.3
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• pp.111-117
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• 2003

The XTR public key system has advantage of short key length and fast computing speed. So, the XTR is used usefully in complicated operation. In this paper, we propose a new algorithm of double exponentiation operation and a proxy signature protocol based on the XTR. The double exponentiation operation should be executed to apply XTR for the proxy signature protocol. But this algorithm is inappropriate, because two secret key has to be blown in existent operation algorithm. New algorithm enable double exponentiation operation with proxy signer's secret key and public information. And the XTR is used to generation and verification of proxy at proxy signature protocol. Therefore proxy signature based on the XTR has basic advantage of the XTR. These advantage can be used in internet as well as mobile.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.13 no.1
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• pp.11-18
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• 2003

As the Internet moves to mobile environment, one of the most serious problems for the security is to required a new security Protocol with safety and efficiency. To solve the problem. we Propose a new Protocol that reduces the communication franc and solves the problem associated with the private security keys supplied by the trusted third party. The protocol is a non-Interactive oblivious transfer protocol, based on the EIGamal public-key algorithm. Due to its Non-Interactive oblivious transfer protocol, it can effectively reduce communication traffic in server-client environment. And it is also possible to increase the efficiency of protocol through the mechanism that authentication probability becomes lower utilizing a challenge selection bit. The protocol complexity becomes higher because it utilizes double exponentiation. This means that the protocol is difficult rather than the existing discrete logarithm or factorization in prime factors. Therefore this can raise the stability of protocol.

• Current Optics and Photonics
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• v.3 no.2
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• pp.119-127
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• 2019

A new secret-key-sharing cryptosystem using optical phase-shifting digital holography is proposed. The proposed secret-key-sharing algorithm is based on the Diffie-Hellman key-exchange protocol, which is modified to an optical cipher system implemented by a two-step quadrature phase-shifting digital holographic encryption method using orthogonal polarization. Two unknown users' private keys are encrypted by two-step phase-shifting digital holography and are changed into three digital-hologram ciphers, which are stored by computer and are opened to a public communication network for secret-key-sharing. Two-step phase-shifting digital holograms are acquired by applying a phase step of 0 or ${\pi}/2$ in the reference beam's path. The encrypted digital hologram in the optical setup is a Fourier-transform hologram, and is recorded on CCDs with 256 quantized gray-level intensities. The digital hologram shows an analog-type noise-like randomized cipher with a two-dimensional array, which has a stronger security level than conventional electronic cryptography, due to the complexity of optical encryption, and protects against the possibility of a replay attack. Decryption with three encrypted digital holograms generates the same shared secret key for each user. Schematically, the proposed optical configuration has the advantage of producing a kind of double-key encryption, which can enhance security strength compared to the conventional Diffie-Hellman key-exchange protocol. Another advantage of the proposed secret-key-sharing cryptosystem is that it is free to change each user's private key in generating the public keys at any time. The proposed method is very effective cryptography when applied to a secret-key-exchange cryptosystem with high security strength.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.9 no.1
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• pp.108-113
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• 2008

A proposed system can decrypt each contents block through a double buffer algorithm which can continually buffer contents by dividing a multimedia contents into some blocks and provides more improved method of encryption than existing system by being not capable of decrypting the whole multimedia contents if one key is exposed. Also, using digital signature and public encryption algorithm for mutual authentication between systems, this paper proposes the system which sends and encrypts symmetric keys for contents encryption through SOAP messages.

• Journal of Microbiology and Biotechnology
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• v.27 no.2
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• pp.335-341
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• 2017

The complexity of the bacterial recombination system is a barrier for the construction of bacterial mutants for the further functional investigation of specific genes. Several protocols have been developed to inactivate genes from the genus Pseudomonas. Those protocols are complicated and time-consuming and mostly do not enable easy construction of multiple knock-ins/outs. The current study describes a single and double crossover-recombination system using an optimized vector-free allele-exchange protocol for gene disruption and gene replacement in a single species of the family Pseudomonadaceae. The protocol is based on self-ligation (circularization) for the DNA cassette which has been obtained by overlapping polymerase chain reaction (Fusion-PCR), and carries an antibiotic resistance cassette flanked by homologous internal regions of the target locus. To establish the reproducibility of the approach, three different chromosomal genes (ncRNA31, rpoN, rpoS) were knocked-out from the root-associative bacterium Pseudomonas stutzeri A1501. The results showed that the P. stutzeri A1501 mutants, which are free of any plasmid backbone, could be obtained via a single or double crossover recombination. In order to optimize this protocol, three key factors that were found to have great effect on the efficiency of the homologous recombination were further investigated. Moreover, the modified protocol does not require further cloning steps, and it enables the construction of multiple gene knock-in/out mutants sequentially. This work provides a simple and rapid mutagenesis strategy for genome editing in P. stutzeri, which may also be applicable for other gram-negative bacteria.

• 한국정보통신설비학회:학술대회논문집
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• 2007.08a
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• pp.147-150
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• 2007

This paper presents an advanced RFID reader system implementing multi-protocols and multi-standards at 900MHz. In accordance with the strict regulations specified by ISO 18000-6 B-Type and EPC Global Gen 2, we have designed corresponding systemic factors which meet the domestic radio frequency utilizing bands of 910-914MHz. In addition, we develop numerous crucial factors of system compatibility options including SSB (Single-Side Band) and DSB (Double-Side Band) specifications, also OOK (On-Off Keying), ASK (Amplitude Shift Keying) and PR-ASK (Phase Reversed-Amplitude Shift Keying) modulation formula. Remarkable technical features of system in this paper can be the direct conversion routines using I/Q Modulation/Demodulation respectively, and Full-Duplex formulation operating at identical frequency bands.

• Journal of Korea Multimedia Society
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• v.15 no.8
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• pp.1048-1058
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• 2012

This paper proposes the DDMPF(Distributed Data Management Protocol using FAT) which prevents data loss and keeps the security of self-organized storages by comprising a client, a storage server, and a verification server in clouding environment. The DDMPF builds a self-organized storage server, solves data loss by decentralizing the partitioned data in it in contrast to the centralized problem and the data loss caused by the storage server problems of existing clouding storages, and improves the efficiency of distributed data management with FAT(File Allocation Table). And, the DDMPF improves the reliability of data by a verification server's verifying the data integrity of a storage server, and strengthens the security in double encryption with a client's private key and the system's master key using EC-DH algorithm. Additionally, the DDMPF limits the number of verification servers and detects the flooding attack by setting the TS(Time Stamp) for a verification request message and the replay attack by using the nonce value generated newly, whenever the verification is requested.

• Journal of Information Processing Systems
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• v.17 no.1
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• pp.63-74
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• 2021

According to the double-phase cluster-head election method (DCE), the final cluster heads (CHs) sometimes are located at the edge of cluster. They have a long distance from the base station (BS). Sensor data is directly transmitted to BS by CHs. This makes some nodes consume much energy for transmitting data and die earlier. To address this problem, energy efficient multi-hop cluster-head election strategy (EEMCE) is proposed in this paper. To avoid taking these nodes far from BS as CH, this strategy first introduces the distance from the sensor nodes to the BS into the tentative CH election. Subsequently, in the same cluster, the energy of tentative CH is compared with those of other nodes, and then the node that has more energy than the tentative CH and being nearest the tentative CH are taken as the final CH. Lastly, if the CH is located at the periphery of the network, the multi-hop method will be employed to reduce the energy that is consumed by CHs. The simulation results suggest that the proposed method exhibits higher energy efficiency, longer stability period and better scalability than other protocols.