1 简介
一种数字图像加密算法,通过Lorentz混沌系统生成三个混沌序列,混沌序列用于置乱像素位置,将置乱后的图像分成高四位和低四位两个4位矩阵,在低四位矩阵中随机提取100个值,用这100个值之和将混沌序列改造成两个015的随机序列,对高四位矩阵进行两轮值扩散,最后将两个矩阵合成8比特图像矩阵,得到密文图像,该算法具有显著的一次一密的特性,加密效果好,且通过相应的解密方法能够有效地将加密图像还原成原图像.
2 部分代码
% 读取图像'lena.bmp'
clc
clear all
close all
I = imread('lena.png');
figure;
imshow(I);
title('original image');
drawnow;
% 产生实数混沌序列x,y,z
n =size(I,1)*size(I,2);
level =0;
s=10;
r=28;
b=8/3;
x0=1.1840;
y0=1.3627;
z0=1.2519;
h=0.001
[x,y,z]=lorentz(n,level,s,r,b,x0,y0,z0,h);
drawnow;
% 对实数混沌序列进行预处理
X=1000*x-round(1000*x);
Y=1000*y-round(1000*y);
Z=1000*z-round(1000*z);
drawnow;
% 产生索引序列lx,ly,lz
[X1,lx]=sort(X);
[Y1,ly]=sort(Y);
[Z1,lz]=sort(Z);
drawnow;
% 对图像进行加密
A=I(:,:,1);
B=I(:,:,2);
C=I(:,:,3);
A1=reshape(A,1,[]);
B1=reshape(B,1,[]);
C1=reshape(C,1,[]);
A2(1:n)=A1(lx);
B2(1:n)=B1(ly);
C2(1:n)=C1(lz);
A3=reshape(A2,size(I,1),size(I,2));
B3=reshape(B2,size(I,1),size(I,2));
C3=reshape(C2,size(I,1),size(I,2));
drawnow;
% 显示加密后的图像
I(:,:,1)=A3;
I(:,:,2)=B3;
I(:,:,3)=C3;
figure;
imshow(I);
title('encrypted image');
imwrite(I,'lena1.bmp');
drawnow;
% 对图像进行解密
I1=imread('lena1.bmp');
A4=I1(:,:,1);
B4=I1(:,:,2);
C4=I1(:,:,3);
A5=reshape(A4,1,[]);
B5=reshape(B4,1,[]);
C5=reshape(C4,1,[]);
A6(lx)=A5(1:n);
B6(ly)=B5(1:n);
C6(lz)=C5(1:n);
A7=reshape(A6,size(I1,1),size(I1,2));
B7=reshape(B6,size(I1,1),size(I1,2));
C7=reshape(C6,size(I1,1),size(I1,2));
I1(:,:,1)=A7;
I1(:,:,2)=B7;
I1(:,:,3)=C7;
drawnow;
% 显示解密后的图像
figure;
imshow(I1);
title('decrypted image');
imwrite(I1,'lena2.bmp');
drawnow;
% 错误密码解密后的图像x1=1.1840000001，y1=1.3627000001，z1=1.2519000001
I2=imread('lena1.bmp');
n =size(I2,1)*size(I2,2);
level =0;
s=10;
r=28;
b=8/3;
x1=1.1840000001;
y1=1.3627000001;
z1=1.2519000001;
h=0.001
[x2,y2,z2]=lorentz(n,level,s,r,b,x1,y1,z1,h);
X2=1000*x2-round(1000*x2);
Y2=1000*y2-round(1000*y2);
Z2=1000*z2-round(1000*z2);
[X3,lx1]=sort(X2);
[Y3,ly1]=sort(Y2);
[Z3,lz1]=sort(Z2);
A8=I2(:,:,1);
B8=I2(:,:,2);
C8=I2(:,:,3);
A9=reshape(A8,1,[]);
B9=reshape(B8,1,[]);
C9=reshape(C8,1,[]);
A10(lx1)=A9(1:n);
B10(ly1)=B9(1:n);
C10(lz1)=C9(1:n);
A11=reshape(A10,size(I2,1),size(I2,2));
B11=reshape(B10,size(I2,1),size(I2,2));
C11=reshape(C10,size(I2,1),size(I2,2));
I2(:,:,1)=A11;
I2(:,:,2)=B11;
I2(:,:,3)=C11;
figure;
imshow(I2);
title('error decrypted image');
imwrite(I2,'lena3.bmp');
drawnow;
3 仿真结果
4 参考文献
[1]徐舟. 四度时空坐标变换的图像及其应用[J]. 中国民航学院学报, 1999.
[2]陈世强等. "一种基于位平面和高维混沌系统的数字图像加密方法.".
部分理论引用网络文献，若有侵权联系博主删除。
5 MATLAB代码与数据下载地址
见博客主页
