• Proceedings of the IEEK Conference
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• 2002.06b
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• pp.341-344
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• 2002

The importance of protection for information is increasing by the rapid development of information communication and network. Asymmetric crypto-system is the mainstream in encryption system rather than symmetric cryptosystem by above reasons. But asymmetric cryptosystem is restricted in applying to application fields by the reason it takes more times to process than symmetric cryptosystem. In this paper, the proposed cryptosystem uses an algorithm that combines block cipherment with stream ciphcrment. Proposed cryptosystem has a high stability in aspect of secret rate by means of transition of key sequence according to the information of plaintext while asymmetric /symmetric cryptosystern conducts encipherment/decipherment using a fixed key Consequently, it is very difficult to crack although unauthenticator acquires the key information. So, the proposed encryption system which has a certification function of asymmetric cryptosystcm and a processing time equivalent to symmetric cryptosystcm will be highly useful to authorize data or exchange important information.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.40 no.9
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• pp.702-713
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• 2003

The importance of protection for data and information is increasing by the rapid development of information communication and network. And the concern for protecting private information is also growing due to the increasing demand for lots of services by users. Asymmetric cryptosystem is the mainstream in encryption system rather than symmetric cryptosystem by above reasons. But asymmetric cryptosystem is restricted in applying fields by the reason it takes more times to process than symmetric cryptosystem. In this paper, encryption system which executes authentication works of asymmetric cryptosystem by means of symmetric cryptosystem. The proposed cryptosystem uses an algorithms combines that combines block cipherment with stream cipherment and has a high stability in aspect of secret rate by means of transition of key sequence according to the information of plaintext while symmetric/asymmetric cryptosystem conducts encipherment/deciphermeent using a fixed key. Consequently, it is very difficult to crack although unauthenticator acquires the key information. So, the proposed encryption system which has a certification function of asymmetric cryptosystem and a processing time equivalent to symmetric cryptosystems will be highly useful to authorize data or exchange important information.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.14 no.6
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• pp.3-13
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• 2004

Kvarnstrom et al. ${in}^{[10]}$ proposed a rule protection scheme by using one-way hash function to protect rules in security systems over ubiquitous environment. Son et at. ${in}^{[5-6]}$ also prooposed a rule protection scheme for Snort, which is one of the most common IDS. These schemes provide security only for the header information but not for its contents. To solve this problem, this paper presents a scheme based on the symmetric cryptosystem over Snort not only for the header information but also contents. This paper uses the key management based on PCMCIA security module proposed ${by}^{[12]}$ for the symmetric cryptosystem. Our scheme could be adjusted to other security systems, which use the rule based detection.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.12 no.6
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• pp.71-80
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• 2002

To provide the confidentiality of messages transmitted over the network, the use of cryptographic system is increasing gradually and the hybrid cryptosystem, which combines the advantages of the symmetric cryptosystem and the public key cryptosystem is widely used. In this paper, we proposes a new hybrid cryptosystem capable of providing implicit authentication for the sender of the ciphertext by means of the 1-pass key distribution protocol that offers implicit key authentication, hash function and symmetric cryptosystem. Also, we describe some examples such as the Diffie-Hellman based system and the Nyberg-Ruppel based system. The proposed hybrid cryptosystem is an efficient more than general public key cryptosystems in the aspect of computation work and provides implicit authentication for the sender without additional increase of the communication overhead.

• Journal of the Korea Society of Computer and Information
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• v.9 no.2
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• pp.125-130
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• 2004

With development of information communications and network environments security importance to the informations deepen as time goes. In this viewpoint, cryptosystem is developing but proportionally cracking and hacking technology is developing Therefore, in this paper we proposed and designed block cryptosystem with byte variable operation. Designed cryptosystem based on byte operation is safe than existed cryptosystem because it is not generate the fixed DC and LC characteristics. Additionally, proposed cryptosystem have high processing rate and authenticated operation. Therefore proposed cryptosystem is considered to many aid in the network fields.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.12 no.5
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• pp.2322-2326
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• 2011

General cryptosystem uses differently the data and key value for the increment of security level, processes the repetition of limited number and increases the periodic feature of LFSR similar infinite series. So, it cause the efficiency of the cryptosystem. In this thesis, proposed algorithm is composed of reformat, permutation, data cipher block and key scheduler which is applied the new function by mixed symmetric cryptography and asymmetric cryptography. We design the cryptosystem of smart card using the common Synopsys and simulate by ALTERA MAX+PLUS II at 40MHz. Consequently, we confirm the 52% increment of processing rate and the security level of 16 rounds.

• Journal of Internet Computing and Services
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• v.17 no.5
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• pp.97-110
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• 2016

Cryptanalysis is very important step for auditing and checking strength of any cryptosystem. Some of these cryptosystem ensures confidentiality and security of large information exchange from source to destination using symmetric key cryptography. The cryptanalyst investigates the strengths and identifies weakness key as well as enciphering algorithm. With increase in key size the time and effort required to guess the correct key increases so trend is increase key size from 8, 16, 24, 32, 56, 64, 128 and 256 bits to strengthen the cryptosystem and thus algorithm continues without compromise on the cost of time and computation. Automatic Variable Key (AVK) approach is an alternative to the approach of fixing up key size and adding security level with key variability adds new dimension in the development of secure cryptosystem. Likewise, whenever any new cryptographic method is invented to replace per-existing vulnerable cryptographic method, its deep analysis from all perspectives (Hacker / Cryptanalyst as well as User) is desirable and proper study and evaluation of its performance is must. This work investigates AVK based cryptic techniques, in future to exploit benefits of advances in computational methods like ANN, GA, SI etc. These techniques for cryptanalysis are changing drastically to reduce cryptographic complexity. In this paper a detailed survey and direction of development work has been conducted. The work compares these new methods with state of art approaches and presents future scope and direction from the cryptic mining perspectives.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.13 no.1
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• pp.3-10
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• 2003

In this paper, a partially blind signature schemes baled on EC-KCDSA is proposed and we applied it to design an electronic check payment system. Because the proposed partially blind signature scheme uses elliptic curve cryptosystem, it has better performance than any existing schems using RSA cryptosystem. When issuing a refund check, one-time pad secret key is used between the bank and the customer to set up secure channel. So the symmetric key management is not required.

• Journal of the Korea Society of Computer and Information
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• v.8 no.2
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• pp.112-121
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• 2003

Information Protection and cryptography technology is developed with if but solved problem of real time processing and secret maintain. Therefore this paper is Proposed new PRN-SEED(Pseudo-Random Number-SEED) for the increasing secret rate and processing rate perform performance analysis with existed other cryptography algorithms. Proposed new PRN-SEED crypto-algorithm increase in the processing rate than existed algorithms use bit and byte mixed operation with RNG(Random Number Generator). PRN-SEED that performs simultaneous operations have higher 1.03 in the processing rate and 2 in the cryptosystem performance than existed cryptosystems. Implementation for PRN-SEED use Synopsys Design Analyser Ver. 1999.10, samsung KG75 library and Synopsys VHDL Debegger. As a simulation result, symmetric cryptosystem DES operate 416Mbps at the 40MHz and Rijndael operate 612Mbps at the 50MHz. PRN-SEED cryptosystem have gate counting 10K and operate 430Mbps at the 40MHz and 630Mbps at the 50MHz.

• The Pure and Applied Mathematics
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• v.11 no.1
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• pp.1-14
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• 2004

Due to the development of computer network and mobile communications, the security in image data and other related source are very important as in saving or transferring the commercial documents, medical data, and every private picture. Nonetheless, the conventional encryption algorithms are usually focusing on the word message. These methods are too complicated or complex in the respect of image data because they have much more amounts of information to represent. In this sense, we proposed an efficient secret symmetric stream type encryption algorithm which is based on Boolean matrix operation and the characteristic of image data.