一种基于多重散射的光学Hash函数

本文提出了一种基于光与多重散射介质相互作用的光学Hash函数构造方法.该方法创新性地利用多重散射介质对相干调制光的天然随机散射作用,实现了对调制光的"混淆"和"扩散",从而满足了Hash函数的核心功能要求:高安全强度的单向编码/加密.所设计的光电混合系统能有效地模拟Hash函数中的"压缩函数",结合具有特征提取功能的S...

Optical Hash function based on multiple scattering media

Hash functions,which can extract message digest from input messages as output,play an important role in digital signature and authentication.Meanwhile,Hash functions are essential in many cryptographic protocols and regimes.With the research becoming more and more in depth,a series of Hash functions is proposed,such as MD series and SHA series.At the same time,the security analysis and attacks against Hash functions are carried out.The security of Hash functions is threatened.In this case,how to improve the security of the Hash functions becomes the primary concern.In this paper,an optical Hash function based on the interaction between light and multiple scattering media is proposed.Unlike most of the traditional Hash functions which are based on mathematical transformations or complex logic operations,this method innovatively takes advantage of the natural random scattering effect of multiple scattering media on coherently modulated light,and realizes the“confusion”and“diffusion”of modulated light,which satisfies the core functional requirement of the Hash function:one-way encoding/encryption with strong security.The photoelectric hybrid system designed by this method can effectively simulate the"compression function"in the Hash function.Combined with the Sobel filter with feature extraction function,the input data of arbitrary length can be compressed and encrypted into the output with a fixed length of 256-bit(Hash value).The principle of the proposed optical Hash function can be described as follows.1)Two 8-bit images with a size of 16×16 pixels are loaded in SLM1(amplitude-only spatial modulator)and SLM2(phase-only spatial modulator)respectively.2)The coherent wavefront is modulated by SLM1 and SLM2,and then propagates on multiple scattering media.3)A speckle pattern is recorded by CCD because of the confusion of multiple scattering media.4)The features of the speckle pattern,which is extracted by Sobel filter,serve as the input of the next compression function.For the unpredicted and non-duplicated disorder multiple scattering media,it is tremendously difficult to determine the internal state of the multiple scattering media.Therefore,the proposed optical Hash function is considered to have a high security.A series of simulation results shows that the proposed optical Hash function has a good“avalanche effect”and“collision resistance”,and its security performance is comparable to that of the most widely used traditional Hash functions(MD5 and SHA-1).