Earticle

인터넷과 빅데이터 시대에 혼돈을 기반으로 한 디지털 영상암호화 알고리즘에 대한 연구는 정보보안 분야 의 연구 핫스팟 중 하나가 되었다. 기존의 텍스트 데이터에 비해 디지털 이미지는 데이터의 양이 많고 중복 성이 높은 특성을 가지고 있습니다. DES, AES 및 RSA와 같은 기존 방법은 디지털 이미지 암호화 요구 사 항을 충족할 수 없습니다. 초기 민감도와 고유한 임의성 때문에 카오스는 암호화의 혼란 및 확산 개념과 매 우 일치하므로 카오스 이미지 암호화에 대한 연구가 빠르게 발전했습니다. 본 논문에서는 주로 혼돈 영상 암호화에 대한 연구를 수행한다. 평문 영상에 대한 키 의존성을 목표로 비트 평면과 개선된 로지스틱 맵 기 반 영상 암호화 알고리즘을 제안한다. 알고리즘은 스크램블된 일반 텍스트 이미지의 낮은 4비트 비트 매트 릭스를 개선된 물류 맵의 제어 매개변수로 사용하여 일반 텍스트 이미지에 대한 키의 종속성을 높이고 놀 라운 일회성 비밀 특성을 갖습니다. 서로 다른 비트의 이미지 정보에 따라 서로 다른 강도의 암호화 알고리 즘을 설계하여 알고리즘의 효율성을 높입니다. 영상 암호화의 확산 모드를 목표로 하이퍼 카오스 시스템과 블록 모듈로 기반의 영상 암호화 알고리즘을 제안한다. 알고리즘은 하이퍼 카오스 시스템을 사용하여 카오 스 시퀀스를 반복적으로 생성하고, 암호화된 픽셀 주위에 임의의 이미지 블록을 분할하고, 블록의 픽셀 값 에 대해 적분 모듈로 연산을 수행하여 암호화된 픽셀 회색 값을 얻음으로써 확산 범위를 효과적으로 확장 하고 확산의 무작위성을 향상시킵니다.

In the era of Internet and big data, the research of digital image encryption algorithm based on chaos has become one of the research hot spots in the field of information security. Compared with traditional text data, digital images have the characteristics of large amount of data and high redundancy. Traditional methods such as DES, AES and RSA can not meet the requirements of digital image encryption. Because of its initial sensitivity and inherent randomness, chaos is very consistent with the confusion and diffusion concepts of cryptography, so the research on chaotic image encryption has developed rapidly. In this paper, the following research work is mainly focused on chaotic image encryption: Aiming at the dependence of key on plain text image, an image encryption algorithm based on bit plane and improved Logistic map is proposed. The algorithm takes the low 4-Bit bit matrix of the scrambled plain text image as the control parameter of the improved Logistic map, which enhances the dependence of the key on the plain text image, and has a remarkable one-time secret characteristic. According to different bits of image information, encryption algorithms with different strengths are designed to improve the efficiency of the algorithms. Aiming at the diffusion mode of image encryption, an image encryption algorithm based on hyper chaotic system and block modulo is proposed. The algorithm uses hyper chaotic system to alliterative generate chaotic sequences, divides random image blocks around encrypted pixels, and performs integral modulo operation on pixel values in the blocks to obtain encrypted pixel gray values, which effectively expands the diffusion range and enhances the randomness of diffusion.

To enhance the security of the digital image information transmitted through Internet, this paper proposes an image scrambling algorithm based on spiral filling of bits. This algorithm first reads the pixel values of all the odd-number lines in the images successively from top to bottom and then does the same to the even-number lines. All results will be saved in an one-dimensional array. All the elements in the array are transformed into binary digits and saved in a one-dimensional array that is 8 times longer than the previous one. In this new array every element only saves one binary digit. The bit sequences corresponding to the image odd-number lines in this array are rearranged in an inverted order. The arrays disposed into an inverted order successively fill a matrix whose line number is the same as the old image and column number is 8 times of the old image in a direction of heliciform. Then a new matrix is generated. Lastly every 8 elements in this new matrix are considered as 8 binary digits and are transformed into decimal digits. That is how image scrambling is conducted. This algorithm is simple and easy to be realized. Abundant experimental results have shown that the algorithm has well scrambling effect and is able to recover image without distortion.

This paper presents a new image permutation algorithm to improve permutation efficiency. Based on uniform trend theorem and ideal bias theorem, we propose two classes of extractors, which solve the critical problem of any chaotic sequence uniformity. Then, the uniform chaotic sequence is transformed into integer space and the random integers are used to perform one-dimensional data permutation algorithm, which is based on data position interchange. Based on the data vector permutation, a secure and efficient image permutation is presented. Comparing with previous approaches, the proposed scheme is secure and its efficiency is enhanced.

A scrambling approach is a method which is employed on almost all commercially manufactured system including image and video systems. In this paper, we proposed a new scrambling approach which uses random process. We first separate blocks into certain size, and relocated them randomly. This is block shuffling which is proposed for the purpose of randomizing the block location. The relocated blocks have three channels, R, G, and B, and each color channel’s luminance values are complemented. Experimental results show that the proposed method well-protect contents.

With the rapid development of the Internet and the broadband, more and more people transit images on the Internet. Given the information security, some important images must be encrypted when transmitted. Image scrambling serves as one of the powerful encrypting tools. This paper proposes an image scrambling algorithm based on grouping calculation. This algorithm divides every byte of the stored image information into three groups, and swaps the position of each group so that the pixels’ positions are scrambled. And then empower the three groups with corresponding values and do linear calculation for new byte values so that the pixels’ color values are scrambled. The empirical results show that this algorithm has a satisfactory scrambling result.

Scrambling transformation plays an important role in information hiding application, so offering an effective evaluation method for scrambling algorithms is becoming increasingly necessary. The paper firstly analyzed the Arnold transformation process to get some universal rules about the periodicity of scrambling process, then used the improved Intersecting Cortical Model Neural Network (ICMNN) designed especially to extract 1D signatures of the original image and scrambled images which could effectively reflect the image structure changing processing. Finally L1 norm was adopted to evaluate the scrambling degree and the universal rules obtained above were used to verify the results. The experimental results showed that the proposed method could analyze and evaluate the scrambling degree efficiently and had a promising application future.

In this paper, we investigate possible scrambling methods for the JPEG(Joint Photographic Export Group) still image compression standard. In particular, we compare the conventional line rotation and line permutation methods to the DCT block scrambling in terms of the number of bits to be increased and the easiness of buffer control. Computer simulation results show that the DCT block scrambling method is suitable for both data security and buffer control in one-chip JPEG applications.

멀티미디어 콘텐츠를 보호하기 위해 연구되고 있는 방법 중에서 선택암호화(selective encryption) 방식은 멀티미디어 콘텐츠를 부분적으로 암호화하는 방법으로 AES와 같은 전통적인 암호방식을 적용하는 방법과 비교하여 보안성은 떨어지지만 높은 보안성을 요구하지 않는 멀티미디어 콘텐츠 응용 분야에 적용될 수 있다. 본 논문에서는 DPSS(discrete prolate spheroidal sequence)를 이용하여 영상의 대역폭(bandwidth) 확장 없이 영상을 스크램블하는 Van De Ville의 방식과 이에 대한 보안성을 검증한 Shujun Li의 연구를 기초로 하여 영상을 보다 안전하게 스크램블하기 위한 개선 방법을 제안하였다. 제안 방식은 비밀행렬 구성 시에 Hadamard 행렬 대신에 랜덤행렬을 이용하고, 통계적 특성과 비밀 행렬에 대한 예측에 의한 통계적 공격이나 기지평문총격에 대해 랜덤행렬을 가산하여 영상에 대한 랜덤성을 증가시켜 공격에 대한 보안성을 높이고자 하였다. 실험 결과들로부터 기존의 방법에 비해 각 공격에 대해 MAE(mean absolute error)의 값이 각각 25, 13, 80 이상 증가되어 보안성이 증자됨을 확인하였다. 또한 제안 방식은 워터마크 응용에 적용하여 접근 제어나 복사 제어에 적용할 수 있음을 제시하였다.

As one of schemes to protect multimedia content. it is the selective encryption scheme to encrypt partially multimedia content. Compared AES(advanced encryption standard) of traditional encryption, the selective encryption scheme provides low security but is applicable to applications of multimedia content not to require high secrecy. In this paper, we improve the image scrambling scheme proposed by Van De Ville which scrambles an image without bandwidth expansion using DPSS(discrete prolate spheroidal sequence) to make it more secure based on Shujun's research which verifies the secrecy of Van De Ville's scheme. The proposed method utilizes an orthonormalized random matrix instead of Hadamard matrix for secret matrix and to add it for providing high secrecy against statistical attack or known-plaintext attack using some statistical property or estimate of secret matrix from a scrambled image. The experimental results show that the proposed method is more secure than the existing scheme. In addition, we show that the proposed method can be applied to access control or copy control of watermarking application.

본 논문에서는 집적 영상 (integral imaging) 방식과 픽셀 스크램블링 (pixel scrambling) 기술을 이용한 광 영상 암호화 (optical image encryption) 방법을 제안한다. 제안한 방법의 부호화 과정에서는 먼저 입력영상을 여러 개의 작은 사이즈의 블록으로 나누어 픽셀 스크램블링을 한 다음 집적 영상 기술을 이용하여 요소 영상(elemental image)을 생성하고, 이 영상의 안정성을 위하여 2차 픽셀 스크램블링을 수행하여 최종 암호화된 영상을 얻는다. 그리고 복호화 과정에서는 암호화된 영상에 광학적인 집적 영상 복원 기법과 역 픽셀 스크램블링 방법을 사용하여 원 영상을 복원한다. 제안하는 광 암호화 방법에 대해서 크로핑과 같은 데이터 손실 및 노이즈에 대한 컴퓨터 적으로 모의실험을 수행하여 강인성과 유용성을 보였다.