• Journal of information and communication convergence engineering
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• 제15권3호
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• pp.151-159
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• 2017

Steganography, which is popular as an image processing technology, is the art of using digital images to hide a secret message in such a way that its existence can only be discovered by the sender and the intended receiver. This technique has the advantage of concealing secret information in a cover medium without drawing attention to it, unlike cryptography, which tries to convert data into something messy or meaningless. In this paper, we propose two efficient least significant bit (LSB)-based steganography techniques for designing an image-based steganography system on chip using hardware description language (HDL). The proposed techniques manipulate the LSB plane of the cover image to embed text inside it. The output of these algorithms is a stego-image which has the same quality as that of the original image. We also implement the proposed techniques using the Altera field programmable gate array (FPGA) and Quartus II design software.

• 한국정보시스템학회지:정보시스템연구
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• 제10권1호
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• pp.127-146
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• 2001

The area of business applications in the internet are extended enormously in result of fast development of computing and communication technologies, increase of internet use, and use of intranet/extranet in enterprise information system. Widely spread the use of the internet, there are various applications for Business to Business (B to B) or Business to Customer(B to C) model that are based on the intranet or extranet. This paper designed and implemented the Web-based Electronic Bidding System for Business to Business (B to B) model. The technical issues of electronic bidding system in the internet are involved in the connection between web client and server, electronic data interchange for the contract document, and security solution during the bidding and contracting processes. The web-based electronic bidding system in this paper is implemented using Java applet and servlet as a connection interface for web client and server, XML/EDI-based documents for a bid and a contract, and bidding server and notary server for enhancing the security using PKI(Public Key Infrastructure)-based public key cryptography, digital signature and Certification Authority(CA).

• Journal of information and communication convergence engineering
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• 제7권2호
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• pp.98-106
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• 2009

Process Control Systems (PCSs) or Supervisory Control and Data Acquisition (SCADA) systems have recently been added to the already wide collection of wireless sensor networks applications. The PCS/SCADA environment is somewhat more amenable to the use of heavy cryptographic mechanisms such as public key cryptography than other sensor application environments. The sensor nodes in the environment, however, are still open to devastating attacks such as node capture, which makes designing a secure key management challenging. In this paper, a key management scheme is proposed to defeat node capture attack by offering both forward and backward secrecies. Our scheme overcomes the pitfalls which Nilsson et al.'s scheme suffers from, and is not more expensive than their scheme.

• Journal of information and communication convergence engineering
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• 제15권4호
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• pp.212-216
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• 2017

In this paper, we introduce novel techniques to improve the high performance of AE functions on modern high-end IoT platforms (ARM-NEON), which support SIMD and cryptography instruction sets. For the Sophie Germain Counter Mode of operation (SGCM), counter modes of encryption and prime field multiplication are required. We chose the Montgomery multiplication for modular multiplication. We perform Montgomery multiplication in a parallel way by exploiting both the ARM and NEON instruction sets. Specifically, the NEON instruction performed 128-bit integer multiplication and the ARM instruction performed Montgomery reduction, simultaneously. This approach hides the latency for ARM in the NEON instruction set. For a high-speed counter mode of encryptions for both AE functions, we introduced two-level computations. When the tasks were large volume, we switched to the NEON instruction to execute the encryption operations. Otherwise, we performed the encryptions on the ARM module.

• Journal of information and communication convergence engineering
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• 제7권3호
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• pp.340-344
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• 2009

Multi-server password authentication schemes enable remote users to obtain service from multiple servers with single password without separately registering to each server. In 2007, Hu-Niu-Yang proposed an improved efficient password authenticated key agreement scheme for multi-server architecture based on Chang-Lee's scheme proposed in 2004. This scheme is claimed to be more efficient and is able to overcome a few existing deficiencies in Chang-Lee's scheme. However, we find false claim of forward secrecy property and some potential threats such as offline dictionary attack, key-compromise attack, and poor reparability in their scheme. In this paper, we will discuss these issues in depth.

• 디지털산업정보학회논문지
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• 제13권3호
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• pp.43-51
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• 2017

MANET consists of only wireless nodes having limited processing capability. It processes routing and data transmission through cooperation among each other. And it is exposed to many attack threats due to the dynamic topology by movement of nodes and multi-hop communication. Therefore, the reliability of transmitted data between nodes must be improved and security of integrity must be high. In this paper, we propose a method to increase the reliability of transmitted data by providing a secure cryptography protocol. The proposed method used a hierarchical structure to provide smooth cryptographic services. The cluster authentication node issues the cluster authentication key pair and unique key to the nodes. The nodes performs the encryption through two steps of encryption using cluster public key and block encryption using unique key. Because of this, the robustness against data forgery attacks was heightened. The superior performance of the proposed method can be confirmed through comparative experiment with the existing security routing method.

• 전자통신동향분석
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• 제17권6호통권78호
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• pp.146-154
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• 2002

본 고에서는 최근 IT-NT 융합 기술 중 각광받고 있는 양자 정보통신 기술의 기초 이론 및 최신 동향 그리고, 실제적인 시스템 구현을 위한 구성 요소들을 살펴보고자 한다. 양자정보통신 기술은 광자(光子)의 양자역학적 특성에 기반을 둔 기술로서 양자 이론과 밀접한 관련을 가진 기술 분야이다. 일반적으로 양자정보처리 기술은 크게 양자 컴퓨터(quantum computer)와 양자 암호화(quantum cryptography) 기술, 양자 통신(quantum communication) 등으로 구분된다. 양자정보통신의 각 분야 기술이 아직은 기초연구 수준에 있지만 세계적으로 그 중요성을 인식하고 대규모 투자를 아끼지 않는 분야이기 때문에, 이 분야에 대한 투자를 소홀히 하면 기술 종속 또는 기술 후진국으로 전락할 수도 있다. 그러므로, 본 고에서는 외국의 기술 발전 추세에 대처하고 자체적인 관련 기반 기술을 확보하기 위한 기초 이론과 기술 동향에 대해 간략히 살펴보기로 한다.

• ETRI Journal
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• 제34권3호
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• pp.482-484
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• 2012

With the rapid progress of wireless mobile communications, the authenticated key agreement (AKA) protocol has attracted an increasing amount of attention. However, due to the limitations of bandwidth and storage of the mobile devices, most of the existing AKA protocols are not suitable for wireless mobile communications. Recently, Lo and others presented an efficient AKA protocol based on elliptic curve cryptography and included their protocol in 3GPP2 specifications. However, in this letter, we point out that Lo and others' protocol is vulnerable to an offline password guessing attack. To resist the attack, we also propose an efficient countermeasure.

• 한국산학기술학회:학술대회논문집
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• 한국산학기술학회 2010년도 춘계학술발표논문집 1부
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• pp.77-80
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• 2010

일반적인 메일 시스템은 제 3자의 악의적인 목적으로 메일의 내용을 열람했을 경우 모든 내용이 그대로 노출 된다는 위험성을 내포하고 있다. 이러한 문제점을 해결하기 위해서, 본 논문에서는 ARIA를 이용한 메일 암호시스템을 제안한다. 제안한 암호시스템은 메일 내용을 송 수신 하는 쌍방 간의 합의된 비밀 키로 암 복호화하여 악의적인 의도로 메일에 접근했을 경우에도 비밀 키가 노출되지 않는 한메일 내용을 알 수 없도록 설계하였다.

• 전자통신동향분석
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• 제33권6호
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• pp.94-106
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• 2018

A quantum key distribution (QKD) provides in principle an unconditional secure communication unlike the standard public key cryptography depending on the computational complexity. In particular, free-space QKD can give a secure solution even without a fiber-based infrastructure. In this paper, we investigate an overview of recent research trends in the free-space QKD system, including satellite and handheld moving platforms. In addition, we show the key components for a free-space QKD system such as the integrated components, single photon detectors, and quantum random number generator. We discuss the technical challenges and progress toward a future free- space QKD system and components.