• KSII Transactions on Internet and Information Systems (TIIS)
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• v.7 no.9
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• pp.2326-2337
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• 2013

Many applications can be parallelized by using multicore platforms. We propose a load-balancing technique for parallelizing a whole application, whose first module (H.264) has data independency and whose second module (AES) has data dependency. Instead of distributing the first module symmetrically over the multi-core platform, we distribute the data-independent workload asymmetrically in order to start the data-dependent workload as early as possible. Based on the experimental results with a compression/encryption application, we confirm that the asymmetric load balancing can provide better performance than the typical symmetric load balancing.

• The KIPS Transactions:PartC
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• v.8C no.3
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• pp.277-286
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• 2001

본 논문에서는 미국 국립표준기술연구소 차세대 표준 암호 알고리듬으로 선정한 Rijndael 암호 알고리듬과 안정성과 성능에서 인정을 받은 Twofish 암호 알고리듬을 ALTERA FPGA를 사용하여 하드웨어로 구현한다. 두가지 알고리듬에 대해 키스케쥴링과 인터페이스를 하드웨어에 포함시켜 구현한다. 알고리듬의 효율적인 동작을 위해 키스케쥴링을 포함하면서도 구현된 회로의 크기가 크게 증가하지 않으며, 데이터의 암호/복호화 처리 속도가 향상됨을 알 수 있다. 주어진 128-비트 대칭키에 대하여, 구현된 Rijndael 암호 알고리듬은 11개의 클럭 만에 키스케쥴링을 완료하며, 구현된 Twofish 암호 알고리듬은 21개의 클럭 만에 키스케쥴링을 완료한다. 128-비트 입력 데이터가 주어졌을 때, Rijndael의 경우, 10개의 클럭 만에 주어진 데이터의 암호/복호화를 수행하고, Twofish는 16개의 클럭 만에 암호/복호화를 수행한다. 또한, Rijndael은 336.8Mbps의 데이터 처리속도를 보이고, Twofish는 121.2Mbps의 성능을 보임을 알 수 있다.

• Proceedings of the Korean Information Science Society Conference
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• 2005.07a
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• pp.154-156
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• 2005

인터넷의 확산과 컴퓨터 간 상호연결성의 증대로 디지털 자원에 대한 유통 환경이 급속히 변화함에 따라 디지털 형태의 음악, 화상, 영상물, 출판물 등 멀티미디어 자료에 대한 수요가 급격히 증가하고 있다. 하지만 디지털 저작물은 품질에 대한 손상이 없이 복제가 가능하기 때문에 불법복제 방지를 위한 디지털 저작권 보호문제가 중요한 이슈로 대두되고 있다. 본 논문에서는 기존의 암호화 방법보다 다양한 키를 생성하는 알고리즘을 제안하며, 키 생성 알고리즘을 통해 각각 생성된 랜덤 대칭키를 서버에 저장하지 않는 기존의 시스템보다 보안성이 높은 암호화 방법을 제안한다.

• Journal of Advanced Navigation Technology
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• v.17 no.5
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• pp.568-573
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• 2013

In this paper, we propose a differential fault analysis on symmetry structured SPN block cipher proposed in 2008. The target algorithm has the SPN structure and a symmetric structure in encryption and decryption process. To recover the 128-bit secret key of the target algorithm, this attack requires only one random byte fault and an exhaustive search of $2^8$. This is the first known cryptanalytic result on the target algorithm.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.13 no.4
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• pp.29-36
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• 2003

In this paper, we propose a new Two-factor Authentication and Key Exchange(TAKE) protocol that can be applied to low-power PDAs in Public Wireless LAMs using two factor authentication and precomputation. This protocol provides mutual authentication session key establishment, identity privacy, and practical half forward-secrecy. The only computational complexity that the client must perform is one symmetric key encryption and five hash functions during the runtime of the protocol.

• Journal of Advanced Information Technology and Convergence
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• v.9 no.2
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• pp.115-123
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• 2019

White-box cryptography is an implementation technique in order to protect secret keys of cryptographic algorithms in the white-box attack model, which is the setting that an adversary has full access to the implementation of the cryptographic algorithm and full control over their execution. This concept was introduced in 2002 by Chow et al., and since then, there have been many proposals for secure implementations. While there have been many approaches to construct a secure white-box implementation for the ciphers with SPN structures, there was no notable result about the white-box implementation for the block ciphers with Feistel structure after white-box DES implementation was broken. In this paper, we propose a secure white-box implementation for a block cipher SEED with Feistel structure, which can prevent the previous known attacks for white-box implementations. Our proposal is simple and practical: it is performed by only 3,376 table lookups during each execution and the total size of tables is 762.5 KB.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.24 no.4
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• pp.739-751
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• 2014

We are using our smartphone for our business as well as ours lives. Thus, user's privacy data and a company secret are stored at smartphone. By the way, the saved data on smartphone database can be exposed to a malicous attacker when a malicous app is installed in the smartphone or a user lose his/her smartphone because all data are stored as form of plaintext in the database. To prevent this disclosure of personal information, we need a database encryption method. However, if a database is encrypted, it causes of declining the performance. For example, when we search specific data in condition with encrypted database, we should decrypt all data stored in the database or search sequentially the data we want with accompanying overhead[1]. In this paper, we propose an efficient and searchable encryption method using variable length bloom filter under limited resource circumstances(e.g., a smartphone). We compare with existing searchable symmetric encryption. Also, we implemented the proposed method in android smartphone and evaluated the performance the proposed method. As a result through the implementation, We can confirm that our method has over a 50% improvement in the search speed compared to the simple search method about encrypted database and has over a 70% space saving compared to the method of fixed length bloom filter with the same false positive rate.

• Journal of the Korea Convergence Society
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• v.5 no.4
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• pp.101-106
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• 2014

Most peoples are used to prefer to view the video contents rather than the other contents since the video contents are more easy to understand with both their eyes and ears. As the wide spread use of smartphones, the demands for the contents services are increasing rapidly. To promote the contents business, it's important to provide security of subscriber authentication and corresponding communication channels through which the contents are delivered. Generally, symmetric key encryption scheme is used to protect the contents in the channel, and the session key should be upadated periodically for the security reasons. In addition, to protect viewing paid contents by illegal users, the proxy authentication should not be allowed. In this paper, we propose biometric based user authentication and one time key generation models. The proposed model is consist of biometric template registration, session key generation and chanel encryption steps. We analyze the difference and benefits of our model with existing CAS models which are made for CATV contents protection, and also provides applications of our model in electronic commerce area.

• Journal of Korea Multimedia Society
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• v.8 no.4
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• pp.525-535
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• 2005

A password-based authenticated tripartite key exchange protocol based on A. Joux's protocol was proposed. By using encryption scheme with shared password, we can resolve man-in-the-middle attack and lack of authentication problems. We also suggested a scheme to avoid the offline dictionary attack to which symmetric encryption schemes are vulnerable. The proposed protocol does not require a trusted party which is required in certificate or identity based authentication schemes. Therefore in a ad hoc network which is difficult to install network infrastructure, the proposed protocol would be very useful. The proposed protocol is more efficient in computation aspect than any existing password-based authenticated tripartite key exchange protocols. When it is used as a base line protocol of tree based group key exchange protocol, the computational weak points of the proposed protocol are compensated.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.21 no.5
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• pp.14-21
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• 2020

In order to provide confidential services between two communicating parties, block data encryption using a symmetric secret key is applied. A power analysis attack on a cryptosystem is a side channel-analysis method that can extract a secret key by measuring the power consumption traces of the crypto device. In this paper, we propose an attack model that can recover the secret key using a power analysis attack based on a deep learning convolutional neural network (CNN) algorithm. Considering that the CNN algorithm is suitable for image analysis, we particularly adopt the recurrence plot (RP) signal processing method, which transforms the one-dimensional power trace into two-dimensional data. As a result of executing the proposed CNN attack model on an XMEGA128 experimental board that implemented the AES-128 encryption algorithm, we recovered the secret key with 22.23% accuracy using raw power consumption traces, and obtained 97.93% accuracy using power traces on which we applied the RP processing method.