• The Journal of Korean Institute of Communications and Information Sciences
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• v.22 no.9
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• pp.1916-1932
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• 1997

The synchronous stream cipher which require absoulte clock synchronization has the problem of synchronization loss by cycle slip. Synchronization loss makes the state which sender and receiver can't communicate with each other and it may break the receiving system. To lessen the risk, we usually use a continuous resynchronization method which achieve resynchronization at fixed timesteps by inserting synchronization pattern and session key. While we can get resynchronization effectively by continuous resynchroniation, there are some problems. In this paper, we proposed an adaptive resynchronization algorithm for cipher system using HDLC protocol. It is able to solve the problem of the continuous resynchronization. The proposed adaptive algorithm make resynchronization only in the case that the resynchronization is occurred by analyzing the address field of HDLC. It measures the receiving rate of theaddress field in the decision duration. Because it make resynchronization only when the receiving rate is greateer than the threshold value, it is able to solve the problems of continuous resynchronization method. When the proposed adaptive algorithm is applied to the synchronous stream cipher system in packet netork, it has addvance the result in R_e and D_e.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.11 no.1
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• pp.13-23
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• 2001

This paper implemented into hardware SEED which is the KOREA standard 128-bit block cipher. First, at the respect of hardware implementation, we compared and analyzed SEED with AES finalist algorithms - MARS, RC6, RIJNDAEL, SERPENT, TWOFISH, which are secret key block encryption algorithms. The encryption of SEED is faster than MARS, RC6, TWOFISH, but is as five times slow as RIJNDAEL which is the fastest. We propose a SEED hardware architecture which improves the encryption speed. We divided one round into three parts, J1 function block, J2 function block J3 function block including key mixing block, because SEED repeatedly executes the same operation 16 times, then we pipelined one round into three parts, J1 function block, J2 function block, J3 function block including key mixing block, because SEED repeatedly executes the same operation 16 times, then we pipelined it to make it more faster. G-function is implemented more easily by xoring four extended 4 byte SS-boxes. We tested it using ALTERA FPGA with Verilog HDL. If the design is synthesized with 0.5 um Samsung standard cell library, encryption of ECB and decryption of ECB, CBC, CFB, which can be pipelined would take 50 clock cycles to encrypt 384-bit plaintext, and hence we have 745.6 Mbps assuming 97.1 MHz clock frequency. Encryption of CBC, OFB, CFB and decryption of OFB, which cannot be pipelined have 258.9 Mbps under same condition.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.9 no.8
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• pp.1741-1748
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• 2005

In this paper, we describe VLSI design and performance evaluation of OCB-AES crytographic algorithm that simulataneously provides privacy and authenticity. The OCB-AES crytographic algorithm sovles the problems such as long operation time and large hardware of conventional crytographic system, because the conventional system must implement the privancy and authenticity sequentially with seqarated algorithms and hardware. The OCB-AES processor with area-efficient modular offset generator and tag generator is designed using IDEC Samsung 0.35um standard cell library and consists of about 55,700 gates. Its cipher rate is about 930Mbps and the number of clock cycles needed to generate the 128-bit tags for authenticity and integrity is (m+2)${\times}$(Nr+1), where m and Nr represent the number of block for message and number of rounds for AES encryption, respectively. The OCB-AES processor can be applicable to soft cryptographic IP of IEEE 802.11i wireless LAN and Mobile SoC.

• Journal of the Institute of Electronics Engineers of Korea CI
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• v.43 no.3 s.309
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• pp.10-19
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• 2006

In this paper, we propose 128-bit chaotic block encryption scheme using a PLCM(Piecewise Linear Chaotic Map) having a good dynamical property. The proposed scheme has a block size of 12n-bit and a key size of 125-bit. The encrypted code is generated from the output of PLCM. We show the proposed scheme is very secure against statistical attacks and have very good avalanche effect and randomness properties.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.27 no.4
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• pp.951-959
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• 2017

Under the assumption that there is available some additional information other than plaintext-ciphertext pairs, the security of the RSA cryptosystem has been analyzed by the attack methods such as the side-channel attacks and the lattice-based attacks. Recently, based on the data retention property of the powered-off DRAMs, the so called cold boot attack was proposed in the literature, which is focusing on recovering the various cryptosystems' key from some auxiliary information. This paper is dealing with the problem of recovering the RSA private key with erasures and errors and proposes a new key recovery algorithm which is shown to have better performance than the previous one introduced by Kunihiro et al.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.11 no.10
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• pp.3942-3949
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• 2010

Since existing Nate-on Messenger application stores users' personal information in the database of its server, it is extremely venerable to internal threats, not to mention the communication data being transmitted without any safety measures. To solve such problematic areas of the existing application, we have developed a safer messenger application. The messenger application proposed in this paper discloses only the least required personal information of its users and the rest of the personal information is safely encrypted in the database using private passwords. This protective measure prevents the administrator or a third party from misusing the information since he/she will not be able access the information. In addition, users will be able to freely and safely communicate using this new messenger since transmitted data will also be encrypted.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.25 no.4
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• pp.719-726
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• 2015

As big-data and cloud security technologies become popular, many researchers have recently been conducted on faster and lighter encryption. As a result, National Security Research Institute developed LEA which is lightweight and fast block cipher. To date, there have been various studies on lightweight encryption algorithm (LEA) for speeding up using GPU rather than conventional CPU. However, it is rather difficult to explore any guideline how to manipulate the GPU for the efficient usage of the LEA. Therefore, we introduce a guideline which explains how to implement and design the optimal LEA using GPU.

• Journal of KIISE:Information Networking
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• v.28 no.1
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• pp.45-55
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• 2001

CORBA 보안 서비스는 네트워크를 기반으로 하는 분산 환경 하에서 데이터 전송 시 사용자가 요구하는 수준의 비밀성 보장과 무결성 제공을 위해 비보호 무결성, 비밀성, 부결성 및 비밀성과 같은 파라미터를 갖는 QoP 기능을 지원하고 있다 그러나 기존의 QoP 기능은 전자상거래, 재무, 통신 CORBA Med와 같은 광범위한 CORBA의 응용 영역들간에 특정 암호화 알고리즘에 대한 서로 다른 정책을 가질 경우 전송되는 데이터에 대한 무결성과 비밀성을 지원할 수 없는 문제접을 갖고 있다. 이를 해결하기 위하여 본논문에서는 광범위한 CORBA의 응용영역들간에 데이터 전송 시 암호화 알고리즘 관리 및 제어기능을 개선한 QoP 모델을 제안한다. 개선된 QoP 관리 및 제어 모델은 OMG에서 발표한 RFP의 요구사항을 기반으로 설계되었으며 특정 암호화 알고리즘들의 관리와 실행중에 사용되는 암호화 알고리즘의 변경제어와 암/복호화시 비도 설정을 지원하다, 구현 결과 개선된 QoP 관리 및 제어 모델은 CORBA IDL 로 설계하여 개발자로 하여금 응용개발의 용이성을 부여하였으며 광범위한 CORBAdmd용 영역들간에 암호화 알고리즘에 대한 QoP 기능을 지원한다. 또한 ISO/IEC 8824(ASN. 1)에서 정의된 OID를 사용하여 암호화 알고리즘의 호환성을 제공한다.

• The Journal of the Korea Contents Association
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• v.1 no.1
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• pp.74-82
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• 2001

Visual cryptography made it possible to decrypt the Information encrypted by thresholding scheme not with digital system but with human vision system. This method, however, has some limit in it because of the rack of resolution in both the spatial and amplitude domain. Optical visual cryptography, which used laser system instead of human eyesight, was proposed by conjunction of the optical theory with the cryptography. However, it also had some difficulties because it did not overcome the existing problem of visual cryptography completely. The problem occurred in the process of transferring data processing system from visual to optics. Therefore, it is appropriate to approach these problems in terms of optics. In this paper, we analysis, in the aspect of frequency, the security characteristics and the noise level occurred in the process of optical visual encryption.

• Journal of the Korea Society of Computer and Information
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• v.16 no.1
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• pp.143-151
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• 2011

Plaintext and key are independent in the existing block cipher. Also, encryption/decryption is performed by using structural features. Therefore, the external environment of suggested mixed cryptographic algorithm is identical with the existing ones, but internally, features of the existing block cipher were meant to be removed by making plaintext and key into dependent functions. Also, to decrease the loads on the authentication process, authentication add-on with dependent characteristic was included to increase the use of symmetric cryptographic algorithm. Through the simulation where the proposed cryptosystem was implemented in the chip level, we show that our system using the shorter key length than the length of the plaintext is two times faster than the existing systems.