• Journal of Information Processing Systems
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• 제11권2호
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• pp.266-279
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• 2015

In this paper, we propose a novel block cipher mode of operation, which is known as the counter chain (CC) mode. The proposed CC mode integrates the cipher block chaining (CBC) block cipher mode of operation with the counter (CTR) mode in a consistent fashion. In the CC mode, the confidentiality and authenticity of data are assured by the CBC mode, while speed is achieved through the CTR mode. The proposed mode of operation overcomes the parallelization deficiency of the CBC mode and the chaining dependency of the counter mode. Experimental results indicate that the proposed CC mode achieves the encryption speed of the CTR mode, which is exceptionally faster than the encryption speed of the CBC mode. Moreover, our proposed CC mode provides better security over the CBC mode. In summary, the proposed CC block cipher mode of operation takes the advantages of both the Counter mode and the CBC mode, while avoiding their shortcomings.

• 한국통신학회논문지
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• 제39B권5호
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• pp.317-322
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• 2014

데이타 보안과 무결성은 유무선 통신 환경에서 데이터 전송 시에 중요한 요소이다. 대량의 데이터는 전송 전에, 통상 암호 연산 모드를 이용한 블록 암호 알고리즘에 의하여 암호화된다. ECB, CBC 등의 기존 연산 모드 외에 블록 암호 연산 모드로 RBF 모드가 제안된 바 있다. 본 논문에서는, 알려진 평문 공격 (known plaintext attack) 및 선택 평문 공격 (chosen plaintext attack)에 대한, RBF 모드의 안전성을 기존 모드들과 비교 분석한 내용을 소개한다. 분석 결과, 기존의 연산 모드들이 알려진/선택 평문 공격에 취약한데 반하여, RBF 모드는 이들 공격에 안전함을 알 수 있었다.

• 한국통신학회논문지
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• 제33권11C호
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• pp.925-931
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• 2008

동영상 표준안 H.264/AVC에서 가변 블록 모드 알고리즘은 압축 성능을 향상시키나 다양한 블록 모드와 모드 결정을 위해 방대한 계산을 필요로 한다. 한편, 결정된 인터 블록 모드들은 블록 영상의 복잡도에 의존하여 복잡한 매크로블록일수록 블록 크기는 더 작아지고 있다. 본 논문은 고속 인터 블록 모드 결정 알고리즘을 제안한다. 제안된 알고리즘은 영상 복잡도를 이용해 유효 인터 블록 모드를 결정 가능성이 큰 블록 모드로 제한하고, 유효블록 모드들에서만 움직임 추정 및 율-왜곡 최적화를 수행한다. 거기에 $16{\times}16$ 블록 모드만을 갖는 유효 블록 모드들에는 고속 움직임 추정 알고리즘인 PDE (partial difference elimination)를 적용시키고 있다. 제안된 알고리즘의 성능 평가를 위해 참조 소프트웨어 JM 9.5에서 화질, 비트율, 부호화 시간이 기존 알고리즘과 비교되었다. 실험 결과는 제안된 알고리즘이 평균 움직임 추정 시간의 약 24.12%를 감소시키며 화질과 비트량을 각각 -0.02dB와 -0.12% 정도로 유지시킬 수 있는 것을 보여주었다.

• 한국방송∙미디어공학회:학술대회논문집
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• 한국방송공학회 2009년도 IWAIT
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• pp.142-147
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• 2009

The recent H.264/AVC video coding standard provides a higher coding efficiency than previous standards. H.264/AVC achieves a bit rate saving of more than 50 % with many new technologies, but it is computationally complex. Most of fast mode decision algorithms have focused on Baseline profile of H.264/AVC. In this paper, a fast block mode decision scheme for P- slices in High profile is proposed to reduce the computational complexity for H.264/AVC because the High profile is useful for broadcasting and storage applications. To reduce the block mode decision complexity in P- pictures of High profile, we use the SAD value after $16{\times}16$ block motion estimation. This SAD value is used for the classification feature to divide all block modes into some proper candidate block modes. The proposed algorithm shows average speed-up factors of 47.42 ${\sim}$ 67.04% for IPPP sequences.

• Journal of Information Processing Systems
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• 제20권1호
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• pp.24-37
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• 2024

To address the requirement for high-speed encryption of large amounts of data, this study improves the widely adopted cipher block chaining (CBC) mode and proposes a controllable parallel cipher block chaining (CPCBC) block cipher mode of operation. The mode consists of two phases: extension and parallel encryption. In the extension phase, the degree of parallelism n is determined as needed. In the parallel encryption phase, n cipher blocks generated in the expansion phase are used as the initialization vectors to open n parallel encryption chains for parallel encryption. The security analysis demonstrates that CPCBC mode can enhance the resistance to byte-flipping attacks and padding oracle attacks if parallelism n is kept secret. Security has been improved when compared to the traditional CBC mode. Performance analysis reveals that this scheme has an almost linear acceleration ratio in the case of encrypting a large amount of data. Compared with the conventional CBC mode, the encryption speed is significantly faster.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2008년도 하계종합학술대회
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• pp.793-794
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• 2008

The block size of intra prediction mode can differentiate the texture area from the homogeneous area of image. This information can be used to enhance the size resolution of image. Specifically, in this paper, we apply the bicubic interpolation or the bilinear interpolation adaptively selected the intra prediction mode of the H.264 compression.

• 한국자동차공학회논문집
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• 제11권3호
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• pp.177-183
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• 2003

Vibration analysis using component mode synthesis method was carried out to identify that to some extent each component contributed to the whole vibration of a powertrain consisting of several components. This analysis helped decide the component to be modified to reduce the powertrain weight, without degrading its current vibration characteristics. As a result, a cylinder block was chosen as a redesign object. Topology optimization analysis was performed to design the topology of the cylinder block whose flange connected with the transmission was chosen to be the design domain. After all, a new prototype of cylinder block was manufactured based on the analysis results for the verification experiment. It was confirmed from the analytical and experimental results that u optimally designed cylinder block had an advantage over the current one in the powertrain weight, with the powertrain vibration characteristics improved slightly.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제11권7호
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• pp.3608-3628
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• 2017

Several block cipher modes of operation have been proposed in the literature to protect sensitive information. However, different security analysis models have been presented for attacking them. The analysis indicated that most of the current modes of operation are vulnerable to several attacks such as known plaintext and chosen plaintext/cipher-text attacks. Therefore, this paper proposes a secure block cipher mode of operation to thwart such attacks. In general, the proposed mode combines one-time chain keys with each plaintext before its encryption. The challenge of the proposed mode is the generation of the chain keys. The proposed mode employs the logistic map together with a nonce to dynamically generate a unique set of chain keys for every plaintext. Utilizing the logistic map assures the dynamic behavior while employing the nonce guarantees the uniqueness of the chain keys even if the same message is encrypted again. In this way, the proposed mode called SPCBC can resist the most powerful attacks including the known plaintext and chosen plaintext/cipher-text attacks. In addition, the SPCBC mode improves encryption time performance through supporting parallelized implementation. Finally, the security analysis and experimental results demonstrate that the proposed mode is robust compared to the current modes of operation.

• 대한임베디드공학회논문지
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• 제12권3호
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• pp.121-130
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• 2017

NAND flash memory has advantages of non-volatility, little power consumption and fast access time. However, it suffers from inability that does not provide to update-in-place and the erase cycle is limited. Moreover, the unit of read/write operation is a page and the unit of erase operation is a block. Therefore, erase operation is slower than other operations. The AGC, the proposed garbage collection policy focuses on not only garbage collection time reduction for real-time guarantee but also wear-leveling for a flash memory lifetime. In order to achieve above goals, we define three garbage collection operating modes: Fast Mode, Smart Mode, and Wear-leveling Mode. The proposed policy decides the garbage collection mode depending on system CPU usage rate. Fast Mode selects the dirtiest block as victim block to minimize the erase operation time. However, Smart Mode selects the victim block by reflecting the invalid page number and block erase count to minimizing the erase operation time and deviation of block erase count. Wear-leveling Mode operates similar to Smart Mode and it makes groups and relocates the pages which has the similar update time. We implemented the proposed policy and measured the performance compare with the existing policies. Simulation results show that the proposed policy performs better than Cost-benefit policy with the 55% reduction in the operation time. Also, it performs better than Greedy policy with the 87% reduction in the deviation of erase count. Most of all, the proposed policy works adaptively according to the CPU usage rate, and guarantees the real-time performance of the system.

• 한국산업정보학회논문지
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• 제22권3호
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• pp.39-47
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• 2017

깊이 화면을 부호화함에 있어서 깊이 화면의 일부를 평면으로 추정하여 부호화하는 평면 부호화 모드를 적용할 수 있다. 본 논문에서는 평면 부호화 모드를 통한 깊이 영상 부호화에서 가변 블록 부호화를 위해 가변 블록 크기를 결정하는 방법을 제안한다. 깊이를 통해 블록 내 화소에 대해 제일 근접한 평면을 추정하는 방법을 통해 평면 부호화를 수행할 수 있다. 평면 부호화를 수행할 때, 가변 블록 부호화를 다음과 같이 적용할 수 있다. 먼저 최대 블록 크기에 대하여 추정 오차를 계산한 뒤 오차가 임계값 이하라면 해당 블록 크기가 선택 된다. 반면 오차가 임계값을 초과한다면 해당 블록이 분할되고 위 과정을 반복한다. 분할된 블록 크기가 최소 블록 크기 미만이 되면 해당 블록은 평면 부호화 모드로 선택되지 않는다. 제안된 방법을 실험한 결과, 부호화하여야 할 블록의 개수가 평면으로 이루어진 영상에서 고정 블록 크기를 이용한 방법에 비해 19%로 줄었다.