• Journal of the Korea Institute of Information Security & Cryptology
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• v.11 no.6
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• pp.77-87
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• 2001

This paper describes a design of cryptographic processor that implements the Rijndael cipher algorithm, the Advanced Encryption Standard algorithm. It can execute both encryption and decryption, and supports only 128-bit block and 128-bit keys. As the processor is implemented only one round, it must iterate 11 times to perform an encryption/decryption. We implemented the ByteSub and InvByteSub transformation using the algorithm for minimizing the increase of area which is caused by different encryption and decryption. It could reduce the memory size by half than implementing, with only ROM. We estimate that the cryptographic processor consists of about 15,000 gates, 32K-bit ROM and 1408-bit RAM, and has a throughput of 1.28 Gbps at 110 MHz clock based on Samsung 0.5um CMOS standard cell library. To our knowledge, this offers more reduced memory size compared to previously reported implementations with the same performance.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.12 no.5
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• pp.75-85
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• 2002

In using elliptic curves in cryptography, it is important to find a secure elliptic curve. The security of elliptic curve cryptosystem is dependent on the cardinality of the given curve. So, it is necessary to count the number of points of a given elliptic curve to obtain secure curve. It is hewn that when the charateristic is two, the most efficient algorithm finding secure curves is combining the Satoh-FGH algorithm with early-abort strategy$^[1]$. In［1］, the authors wrote that they modified SEA algorithm used in early-abort strategy, but they didn't describe the varaint of SEA algorithm. In this paper, we present some modifications of SEA algorithm and show the result of our implementation.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.13 no.3
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• pp.101-110
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• 2003

Secure and reliable group communication is an increasingly active research area prompted by the growing popularity of many types of group-oriented and collaborative applications. The central challenge is secure and efficient group key management. While centralized methods are often appropriate for key distribution in large multicast-style groups, many collaborative group settings require distributed key agreement techniques. Most of prior group key agreement protocols have been focused on reducing the computational costs. One exception is STR protocol that optimizes communicational cost. On the other hand, it requires O(n) number of modular exponentiations. In this paper, we propose a new group key agreement protocol that modifies STR protocol by utilizing pairing based cryptography. The resulting protocol reduces computational cost of STR protocol while preserving the communication cost.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.14 no.4
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• pp.183-194
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• 2004

The proliferation of the Internet and the rapid progress of wire/wireless communication technology makes security of digital images more and more important since the exchanges of digital images occur more and more frequently. And as the tight relationship between chaos theory and cryptography, many researches for development of new encryption systems based on chaotic maps have been widely progressed recently. In this paper, we propose a digital image encryption system based on both one-dimensional PLCM(Piecewise Linear Chaotic Map) and two-dimensional baker map. This proposed system is a product cipher that contains a perturbance-based chaotic stream cipher based on ID PLCM and a chaotic block cipher based on 2D baker map and is very high secure and easily implementable cipher having both a good confusion property and a good diffusion property. And with test results, we showed this system is very secure against statistical attacks.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.15 no.5
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• pp.59-71
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• 2005

A RFID (Radio Frequency Identification) system receives attention as the technology which can realize the ubiquitous computing environment. However, the feature of the RFID tags may bring about new threats to the security and privacy of individuals. Recently, Juels proposed the minimalist cryptography for very low-cost RFID tags, which is secure. but only under the impractical assumption such that an adversary is allowed to eavesdrop only the pre-defined number of sessions. In this paper, we propose a scheme to protect privacy for very low-cost RFID systems. The proposed protocol uses only bit-wise operations without my costly cryptographic function such as hashing, encryption which is secure which is secure against an adversary who is allowed to eavesdrop transmitted message in every session any impractical assumption. The proposed scheme also is more efficient since our scheme requires less datas as well as few number of computations than Juels's scheme.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.21 no.4
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• pp.161-169
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• 2011

There is a consensus in the field of vehicular network security that public key cryptography should be used to secure communications. A certificate revocation list (CRL) should be distributed quickly to all the vehicles in the network to protect them from malicious users and malfunctioning equipment as well as to increase the overall security and safety of vehicular networks. Thus, a major challenge in vehicular networks is how to efficiently distribute CRLs. This paper proposes a CRL distribution method aided by terrestrial digital multimedia broadcasting (T-DMB). By using T-DMB data broadcasting channels as alternative communication channels, the proposed method can broaden the network coverage, achieve real-time delivery, and enhance transmission reliability. Even if roadside units are not deployed or only sparsely deployed, vehicles can obtain recent CRLs from the T-DMB infrastructure. A new transport protocol expert group (TPEG) CRL application was also designed for the purpose of broadcasting CRLs over the T-DMB infrastructure.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.22 no.6
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• pp.1253-1263
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• 2012

As a result of the increased popularity of group oriented applications, the design of an efficient authenticated group key agreement protocol has received a lot of attention. Lee et al. proposed a tree-based group key agreement protocol, which applies a ternary key tree structure and pairing-based cryptography to the key agreement of Dynamic Peer Group. In their protocol, only the group sponsor knows all member's session random keys computes all blinded keys. In addition, when the group sponsor leaves a group, all nodes of the tree should be changed. In this paper, we present the modified protocol that has several sponsors. Since a secret value for each member isn't given to the group sponsor, the key renewing of our protocol is more secure and efficient than that of Lee et al.'s protocol in the previous case. Therefore, our protocol is suitable to Dynamic Peer Groups.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.21 no.2
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• pp.3-11
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• 2011

Evaluation of cube roots in characteristic three finite fields is required for Tate (or modified Tate) pairing computation. The Hamming weights (the number of nonzero coefficients) in the polynomial representations of $x^{1/3}$ and $x^{2/3}$ determine the efficiency of cube roots computation, where $F_{3^m}$is represented as $F_3[x]/(f)$ and $f(x)=x^m+ax^k+b{\in}F_3[x]$ (a, $b{\in}F_3$) is an irreducible trinomial. O. Ahmadi et al. determined the Hamming weights of $x^{1/3}$ and $x^{2/3}$ for all irreducible trinomials. In this paper, we present formulas for cube roots in $F_{3^m}$ using the shifted polynomial basis(SPB). Moreover, we provide the suitable shifted polynomial basis bring no further modular reduction process.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.31 no.3
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• pp.331-340
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• 2021

As the communication industry develops, the development of SoC (System on Chip) is increasing. Accordingly, the paradigm of technology design of industries and companies is changing. In the existing process, companies purchased micro-architecture, but now they purchase ISA (Instruction Set Architecture), and companies design the architecture themselves. RISC-V is an open instruction set based on a reduced instruction set computer. RISC-V is equipped with ISA, which can be expanded through modularization, and an expanded version of ISA is currently being developed through the support of global companies. In this paper, we present benchmarking frameworks ARIA, LEA, and PIPO of Korean block ciphers in RISC-V. We propose implementation methods and discuss performance by utilizing the basic instruction set and features of RISC-V.

• International Journal of Computer Science & Network Security
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• v.21 no.1
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• pp.143-151
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• 2021

The enormous prevalence of transferring official confidential digital documents via the Internet shows the urgent need to deliver confidential messages to the recipient without letting any unauthorized person to know contents of the secret messages or detect there existence . Several Steganography techniques such as the least significant Bit (LSB), Secure Cover Selection (SCS), Discrete Cosine Transform (DCT) and Palette Based (PB) were applied to prevent any intruder from analyzing and getting the secret transferred message. The utilized steganography methods should defiance the challenges of Steganalysis techniques in term of analysis and detection. This paper presents a novel and robust framework for color image steganography that combines Linear Congruential Generator (LCG), simulated annealing (SA), Cesar cryptography and LSB substitution method in one system in order to reduce the objection of Steganalysis and deliver data securely to their destination. SA with the support of LCG finds out the optimal minimum sniffing path inside a cover color image (RGB) then the confidential message will be encrypt and embedded within the RGB image path as a host medium by using Cesar and LSB procedures. Embedding and extraction processes of secret message require a common knowledge between sender and receiver; that knowledge are represented by SA initialization parameters, LCG seed, Cesar key agreement and secret message length. Steganalysis intruder will not understand or detect the secret message inside the host image without the correct knowledge about the manipulation process. The constructed system satisfies the main requirements of image steganography in term of robustness against confidential message extraction, high quality visual appearance, little mean square error (MSE) and high peak signal noise ratio (PSNR).