• Journal of Information Processing Systems
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• 제9권2호
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• pp.271-286
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• 2013

Recently, a pixel-chaotic-shuffling (PCS) method has been proposed by Huang et al. for encrypting color images using multiple chaotic systems like the Henon, the Lorenz, the Chua, and the Rossler systems. All of which have great encryption performance. The authors claimed that their pixel-chaotic-shuffle (PCS) encryption method has high confidential security. However, the security analysis of the PCS method against the chosen-plaintext attack (CPA) and known-plaintext attack (KPA) performed by Solak et al. successfully breaks the PCS encryption scheme without knowing the secret key. In this paper we present an improved shuffling pattern for the plaintext image bits to make the cryptosystem proposed by Huang et al. resistant to chosen-plaintext attack and known-plaintext attack. The modifications in the existing PCS encryption method are proposed to improve its security performance against the potential attacks described above. The Number of Pixel Change Rate (NPCR), Unified Average Changed Intensity (UACI), information entropy, and correlation coefficient analysis are performed to evaluate the statistical performance of the modified PCS method. The simulation analysis reveals that the modified PCS method has better statistical features and is more resistant to attacks than Huang et al.'s PCS method.

• ETRI Journal
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• 제40권5호
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• pp.677-686
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• 2018

A novel data hiding technique based on modified histogram shifting that incorporates multi-bit secret data hiding is proposed. The proposed technique divides the image pixel values into embeddable and nonembeddable pixel values. Embeddable pixel values are those that are within a specified limit interval surrounding the peak value of an image. The limit interval is calculated from the number of secret bits to be embedded into each embeddable pixel value. The embedded secret bits can be perfectly extracted from the stego image at the receiver side without any overhead bits. From the simulation, it is found that the proposed technique produces a better quality stego image compared to other data hiding techniques, for the same embedding rate. Since the proposed technique only embeds the secret bits in a limited number of pixel values, the change in the visual quality of the stego image is negligible when compared to other data hiding techniques.

• Journal of Information Processing Systems
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• 제18권1호
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• pp.59-74
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• 2022

During the last decade, the security of digital images has received considerable attention in various multimedia transmission schemes. However, many current cryptosystems tend to adopt a single-layer permutation or diffusion algorithm, resulting in inadequate security. A hierarchical bilateral diffusion architecture for color image encryption is proposed in response to this issue, based on a hyperchaotic system and DNA sequence operation. Primarily, two hyperchaotic systems are adopted and combined with cipher matrixes generation algorithm to overcome exhaustive attacks. Further, the proposed architecture involves designing pixelpermutation, pixel-diffusion, and DNA (deoxyribonucleic acid) based block-diffusion algorithm, considering system security and transmission efficiency. The pixel-permutation aims to reduce the correlation of adjacent pixels and provide excellent initial conditions for subsequent diffusion procedures, while the diffusion architecture confuses the image matrix in a bilateral direction with ultra-low power consumption. The proposed system achieves preferable number of pixel change rate (NPCR) and unified average changing intensity (UACI) of 99.61% and 33.46%, and a lower encryption time of 3.30 seconds, which performs better than some current image encryption algorithms. The simulated results and security analysis demonstrate that the proposed mechanism can resist various potential attacks with comparatively low computational time consumption.

• 인지과학
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• 제20권4호
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• pp.573-601
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• 2009

이 연구에서는 McConkie와 Rayner(1975)에서 소개된 움직이는-창(moving-window) 방법으로 우리글 읽기에서 지각 폭, 즉 한 고정에서 유용한 정보가 추출되는 범위에 대해 알아보았다. 실험 1에서는 창의 크기를 좌우 대칭인 3, 5, 7, 9, 11, 13, 15자로 조작하여 창이 없는 통제 조건과 수행을 비교했다. 분당 읽을 수 있는 어절의 수(읽기율)를 비교했을 때는 15자 조건은 통제 조건과 수행차이가 없었으나, 나머지 다른 조건들은 통제 조건보다 수행이 저조했다. 고정의 수에서는 15자 조건과 통제 조건은 차이가 없었고, 13자 조건은 통제 조건보다 고정의 수가 많은 경향을 보였고, 다른 조건들은 통제 조건보다 많았다. 빈칸을 한 자로 취급한 글자 도약 거리에서는 결과는 읽기율에서와 같았고, 화소에 기초한 화소 도약 거리에서는 결과 양상이 고정의 수에서와 동일했다. 고정시간에서도 다른 결과들과 비슷했는데, 15자, 13자 및 11자 조건들은 차이가 없었고, 9자 조건들은 통제 조건보다 짧은 경향을 보였으며, 나머지 다른 조건들은 통제 조건보다 대체로 짧았다. 실험 2에서는 지각 폭의 비대칭성을 알아보기 위해 고정 좌측의 창 크기를 0, 1, 2, 3, 4자로 조작하였다. 그 결과, 읽기율, 고정 수, 고정 시간 등에서 1자 조건만 통제 조건과 차이가 나타났고 도약 거리는 조건별로 차이가 나지 않았다. 이 연구에서는 우리글 읽기에서 처음으로 지각 폭의 크기를 여러 지표에서 나타나는 왼쪽으로 1자, 오른쪽으로 6-7자로 추정했다.