encrypt and decrypt the image using Hill cipher

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dani elias
dani elias 2021-1-9
编辑： Image Analyst 2024-11-25
Hello, I have tried to use the normal procedures of Hill Cipher techniques in encrypting the Image. Please,assist me
close all; clear;clc; workspace;
text = imread('lena.bmp');
text = double(text);
[m,n]=size(text);
text=reshape(text,1,m*n);
key = [2 3;1 4]; %key
kinverse= [6 15; 5 16];%inverse matrix
[ new_code,original_image ] = encrypt_decrypt( key,keyinverse,text );
figure(1),imshow(new_code);
figure(2),imshow(original_image);
my encryption decryption function is
function [ new_code,original_image ] = encrypt_decrypt( k,kinv, text )
a=reshape(a,2,(length(text))/2); %convert to two rows
code=mod(k*(a),256);
new_code=reshape(code,1,length(text)); %reshape to one row
new_code=uint8(new_code);
new_code=reshape(new_code,m,n);
text2=new_code;
a =double(text2);
text2=reshape(text2,1,m*n);
b=reshape(a,2,length(text2)/2);
msg=mod(k*(b),256);
new_msg=reshape(msg,1,length(text2));
original_image=uint8(new_msg);
original_image=reshape(original_image,m,n);
end
  4 个评论
显示 2更早的评论
Walter Roberson
Walter Roberson 2024-11-25
@Sumaya
Perhaps you are using a MATLAB older than R2015b. Older versions of MATLAB do not permit mixing scripts and function definitions, so for older versions of MATLAB, the function would need to be written to its own .m file.
Image Analyst
Image Analyst 2024-11-25
编辑：Image Analyst 2024-11-25
@Sumaya, and to build on Walter's reply, versions from 2015b until around r202x would allow you to have a function in the m-file with a script on top (first in the m-file) and the function(s) on the bottom (only) and the function(s) had to end with an "end" statement. Attach your m-file if you need us to correct it for you.

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采纳的回答

Image Analyst
Image Analyst 2021-1-9
text is a built-in function so you can't use that as a variable name. Anyway, it's not text - it's an image so call it grayImage or something more descriptive.
You need to define keyinverse. You don't have it. You have something similar kinverse, but that's a different variable.
You need to define m and n. You really need to use descriptive variable names so it doesn't look like an impenetrable alaphbet soup of code. And add LOTS more comments. Here's a little bit further but this code still needs MAJOR improvement:
close all; clear;clc; workspace;
grayImage = imread('cameraman.tif');
grayImage = double(grayImage);
[m,n]=size(grayImage);
grayImage=reshape(grayImage,1,m*n);
key = [2 3;1 4]; %key
keyinverse= [6 15; 5 16];%inverse matrix
[ new_code,original_image ] = encrypt_decrypt( key, keyinverse,grayImage );
figure(1),imshow(new_code);
figure(2),imshow(original_image);
fprintf('Done running %s.m.\n', mfilename);
function [ new_code,original_image ] = encrypt_decrypt( k, kinv, grayImage )
a=reshape(grayImage,2,(length(grayImage))/2); %convert to two rows
code=mod(k*(a),256);
new_code=reshape(code,1,length(grayImage)); %reshape to one row
new_code=uint8(new_code);
new_code=reshape(new_code,m,n);
text2=new_code;
a =double(text2);
text2=reshape(text2,1,m*n);
b=reshape(a,2,length(text2)/2);
msg=mod(k*(b),256);
new_msg=reshape(msg,1,length(text2));
original_image=uint8(new_msg);
original_image=reshape(original_image,m,n);
end

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