针对传统混沌加密系统密钥空间小,序列复杂度不足以及加密系统单一的问题,提出一种新的基于混沌系统的彩色图像三重置乱加密算法。利用Logistic混沌序列对彩色图像各个像素点的三原色(red green blue,RGB)顺序进行置乱,应用Rabinovich...针对传统混沌加密系统密钥空间小,序列复杂度不足以及加密系统单一的问题,提出一种新的基于混沌系统的彩色图像三重置乱加密算法。利用Logistic混沌序列对彩色图像各个像素点的三原色(red green blue,RGB)顺序进行置乱,应用Rabinovich超混沌系统产生的四维混沌序列中的一组序列对图像的像素点位置进行分块置乱,使用余下的3组序列分通道对图像离散小波变换后的低频系数进行置乱与扩散。该算法充分利用混沌序列特征,将传统混沌置乱加密方法改进,使彩色图像像素点在RGB 3个通道内进行置乱,并将扩散过程与离散小波变换紧密结合。通过实验仿真,对该算法的密钥空间、敏感度、抗统计攻击能力和抗差分攻击能力进行分析,结果表明,该算法能够安全有效地加密图像,保护图像信息安全。展开更多
为了保障时间反演正交频分复(Time reversal-orthogonal frequency division multiplex,TR-OFDM)系统的物理层安全传输,提出了一种基于四元数加密的安全传输算法。该算法主要分为3个步骤:发射端和合法接收端利用估计信道得到加密传输过...为了保障时间反演正交频分复(Time reversal-orthogonal frequency division multiplex,TR-OFDM)系统的物理层安全传输,提出了一种基于四元数加密的安全传输算法。该算法主要分为3个步骤:发射端和合法接收端利用估计信道得到加密传输过程中需要的四元数,即密钥;发射端将需要传输的比特序列做三维映射,利用四元数对三维星座点做旋转加密,调制为OFDM符号并经过时间反演处理之后发射出去;合法用户利用四元数进行解密和解调,从而获得传输的数据,而窃听者因为不知道密钥而无法获得传输信息。因此所提算法保证了系统数据传输的安全性。通过仿真证明本文所提出算法可以使窃听用户的误符号率始终保持在0.5左右;在相同信噪比下,较传统的二维调制,合法用户可以实现更低的误符号率;相较于人工噪声技术方案,本文所提算法不会影响合法用户的误符号率。展开更多
A fast encoding algorithm based on the mean square error (MSE) distortion for vector quantization is introduced. The vector, which is effectively constructed with wavelet transform (WT) coefficients of images, can...A fast encoding algorithm based on the mean square error (MSE) distortion for vector quantization is introduced. The vector, which is effectively constructed with wavelet transform (WT) coefficients of images, can simplify the realization of the non-linear interpolated vector quantization (NLIVQ) technique and make the partial distance search (PDS) algorithm more efficient. Utilizing the relationship of vector L2-norm and its Euclidean distance, some conditions of eliminating unnecessary codewords are obtained. Further, using inequality constructed by the subvector L2-norm, more unnecessary codewords are eliminated. During the search process for code, mostly unlikely codewords can be rejected by the proposed algorithm combined with the non-linear interpolated vector quantization technique and the partial distance search technique. The experimental results show that the reduction of computation is outstanding in the encoding time and complexity against the full search method.展开更多
文摘针对传统混沌加密系统密钥空间小,序列复杂度不足以及加密系统单一的问题,提出一种新的基于混沌系统的彩色图像三重置乱加密算法。利用Logistic混沌序列对彩色图像各个像素点的三原色(red green blue,RGB)顺序进行置乱,应用Rabinovich超混沌系统产生的四维混沌序列中的一组序列对图像的像素点位置进行分块置乱,使用余下的3组序列分通道对图像离散小波变换后的低频系数进行置乱与扩散。该算法充分利用混沌序列特征,将传统混沌置乱加密方法改进,使彩色图像像素点在RGB 3个通道内进行置乱,并将扩散过程与离散小波变换紧密结合。通过实验仿真,对该算法的密钥空间、敏感度、抗统计攻击能力和抗差分攻击能力进行分析,结果表明,该算法能够安全有效地加密图像,保护图像信息安全。
文摘为了保障时间反演正交频分复(Time reversal-orthogonal frequency division multiplex,TR-OFDM)系统的物理层安全传输,提出了一种基于四元数加密的安全传输算法。该算法主要分为3个步骤:发射端和合法接收端利用估计信道得到加密传输过程中需要的四元数,即密钥;发射端将需要传输的比特序列做三维映射,利用四元数对三维星座点做旋转加密,调制为OFDM符号并经过时间反演处理之后发射出去;合法用户利用四元数进行解密和解调,从而获得传输的数据,而窃听者因为不知道密钥而无法获得传输信息。因此所提算法保证了系统数据传输的安全性。通过仿真证明本文所提出算法可以使窃听用户的误符号率始终保持在0.5左右;在相同信噪比下,较传统的二维调制,合法用户可以实现更低的误符号率;相较于人工噪声技术方案,本文所提算法不会影响合法用户的误符号率。
基金the National Natural Science Foundation of China (60602057)the NaturalScience Foundation of Chongqing Science and Technology Commission (2006BB2373).
文摘A fast encoding algorithm based on the mean square error (MSE) distortion for vector quantization is introduced. The vector, which is effectively constructed with wavelet transform (WT) coefficients of images, can simplify the realization of the non-linear interpolated vector quantization (NLIVQ) technique and make the partial distance search (PDS) algorithm more efficient. Utilizing the relationship of vector L2-norm and its Euclidean distance, some conditions of eliminating unnecessary codewords are obtained. Further, using inequality constructed by the subvector L2-norm, more unnecessary codewords are eliminated. During the search process for code, mostly unlikely codewords can be rejected by the proposed algorithm combined with the non-linear interpolated vector quantization technique and the partial distance search technique. The experimental results show that the reduction of computation is outstanding in the encoding time and complexity against the full search method.