基于混沌和位运算的图像加密算法的改进算法和性能分析.doc

%改进算法，及性能分析clearclca=imread(rice.png); a=double(a);m1,n1=size(a);b=zeros(m1,n1*8);for i=1:1:m1 for j=1:1:n1 for t=0:1:7 if mod(floor(a(i,j)/2t),2)=1 b(i,j*8-t)=1; else b(i,j*8-t)=0; end end endendq=4;b1=b;x1(1)=0.3333;for n=1:n1*8+100 x1(n+1)=q*x1(n)*(1-x1(n);endn=101:1:n1*8+100;y1(n-100)=x1(n);z1,l1=sort(y1,2);for i=1:1:n1*8 b1(:,i)=b(:,l1(i);endx2(1)=0.4444;for m=1:m1+100 x2(m+1)=q*x2(m)*(1-x2(m);endm=101:1:m1+100;y2(m-100)=x2(m);z2,l2=sort(y2,2);for i=1:1:m1 b(i,:)=b1(l2(i),:);endfor i=1:1:m1 for j=1:1:n1 a(i,j)=b(i,j*8); for t=1:1:7 a(i,j)= a(i,j)+2t*b(i,j*8-t); end endenda=uint8(a);figure,imshow(a);figure,imhist(a);a=double(a);g(1)=0.5555; %混沌序列的初始值for i=1:1:256*256 %改进算法 t(i)=mod(floor(g(i)*103),256);% if g(i)0.5 g(i+1)=4*q*g(i)*(0.5-g(i); else g(i+1)=1-4*q*(g(i)-0.5)*(1-g(i); endendt=reshape(t,256,256);t=t;for i=1:1:256 for j=1:1:256 s1(i,j)=mod(a(i,j)+t(i,j)*abs(i-j),256); endends1=uint8(s1);figure,imshow(s1);%显示加密图像figure,imhist(s1);%加密图像灰度值s1=double(s1);%解密是加密的反for i=1:1:256 for j=1:1:256 a(i,j)=mod(s1(i,j)-t(i,j)*abs(i-j),256); endendfor i=1:1:m1 for j=1:1:n1 for t=0:1:7 if mod(floor(a(i,j)/2t),2)=1 b(i,j*8-t)=1; else b(i,j*8-t)=0; end end endendfor i=1:1:m1 b1(l2(i),:)=b(i,:);endfor i=1:1:n1*8 b(:,l1(i)=b1(:,i);endfor i=1:1:m1 for j=1:1:n1 a(i,j)=b(i,j*8); for t=1:1:7 a(i,j)= a(i,j)+2t*b(i,j*8-t); end endenda=uint8(a);figure,imshow(a);%求灰度值差异clearclca=imread(rice.png); m1,n1=size(a);a=double(a);gn=zeros(m1-2,n1-2);%定义（m1-2）* （n1-2）的矩阵for i=2:1:255%计算每个与其他四个相邻像素灰度值的差异 for j=2:1:255 am=(a(i,j)-a(i-1,j)2; am=am+(a(i,j)-a(i+1,j)2; am=am+(a(i,j)-a(i,j-1)2; am=am+(a(i,j)-a(i,j+1)2; gn(i-1,j-1)=am/4; endendam=0;for i=1:1:254 for j=1:1:254 am=gn(i,j)+am; endendan=am/(m1-2)*(n1-2);%求各图像的相关性k1=unidrnd(255,1,20);% 生成1*20的矩阵，由1,255之间的数组成k2=randint(1,50,1,255);%生成1*50的矩阵，由1,255之间的数组成for i=1:50for j=1:20x(i,j)=s1(k2(i),k1(j);y(i,j)=s1(k2(i),k1(j)+1);% %水平相关性%y(i,j)=s1(k2(i)+1,k1(j);%竖直相关性%y(i,j)=s1(k2(i)+1,k1(j)+1);%对角相关性endendex=0;%求矩阵x(i,j)的均值for i=1:1:50 for j=1:1:20 ex=ex+x(i,j); endendex=ex/1000;ey=0;%求相关y(i,j)矩阵的均值for i=1:1:50 for j=1:1:20 ey=ey+y(i,j); endendey=ey/1000;cxy=0;%求矩阵x和y的相关系数for i=1:50 for j=1:20 cxy=cxy+(x(i,j)-ex)*(y(i,j)-ey); endendcxy=cxy/1000;dx=0; %求for i=1:50 for j=1:20 dx=dx+(x(