基于非线性级联傅里叶变换的光学Hash函数构造  

Construction of optical Hash function based on nonlinear cascaded Fourier transform

作　　者：何文奇[1] 彭翔[1] 祁永坤[1] 孟祥锋[1] 秦琬[1] 高志 

机构地区：[1]深圳大学光电工程学院,光电子器件与系统教育部/广东省重点实验室,深圳518060 [2]Clemson大学生物医学工程系,501-5 Rhodes Research Center,Clemson,SC 29634,USA

出　　处：《物理学报》2010年第3期1762-1768,共7页Acta Physica Sinica

基　　金：国家自然科学基金(批准号:60907005,60775021);中科院微系统与信息技术研究所项目;中国博士后科学基金(批准号:200902334)资助的课题~~

摘　　要：提出一种基于非线性级联傅里叶变换的光学Hash函数的构造方法.此方法分为两轮单向加密过程,在第一轮中,先将待处理的数字信息以512bit作为数据块编码,将整个数字信息整分成若干个"8×8的256阶灰度图像"(信息平面),然后在光电混合系统中对上述信息平面组做非线性级联傅里叶变换得到一个数值矩阵,对其进行扩展后得到4个信息平面,再对它们做非线性级联傅里叶变换得到64bit的Hash值(hash1);在第二轮中,先将原始信息平面中的每个数值循环左移4位,构造出相应的辅助信息平面组,然后对其做与第一轮相同的单向加密操作,得到hash2,将其与之前生成的hash1组合起来构成最终128bit的Hash值(hash).同时,本文提出采用雪崩效应系数(AEC)作为评价光学Hash函数性能的参数,理论分析和仿真实验均表明,该方法构造的光学Hash函数具有很好的抗碰撞性和良好的雪崩效应.A method of constructing optical Hash function based on nonlinear cascaded Fourier transform is proposed. The proposed method consists of two single one-way encryption processes. In the first process, the digital information is divided to several data blocks with 512-bit each. The data blocks are encoded to 8 by 8 sub-images with 256 gray scales, creating information planes. Then take a nonlinear cascaded Fourier transform of sub-image to generate a data matrix through an optical/digital hybrid system. By extending the data matrix we get four information planes. Again, taking nonlinear cascaded Fourier transform to built inform ation planes, we get a Hash value 64-bit long （hash_1）. In the second process, we shift cydically every numerical value of the original information planes by 4-bit, construct ing auxiliary information planes. Thereafter we take the same operations as we have done in the first process to the Hash value （hash_2）. Once hash_1 and hash_2 obtained, they are combined to form a final Hash value 128-bit long （hash）. Furthermore, the avalanche effect coefficient （AEC） was also proposed to evaluate the performance of the optical Hash function. Theoretical analysis and simulation results are presented to show the effectiveness of optical Hash function constructed by our approach and the constructed optical Hash function has good performance of avalanche effect and collision resistance.

关 键 词：信息光学 光学Hash函数 非线性级联傅里叶变换 雪崩效应 

分 类 号：O438.2[机械工程—光学工程]