Secure Communication: Combining Cryptography & Steganography in MATLAB 🛡️

Steganography is an art of hiding secret information into another cover medium like image, audio, video, etc.
Cryptography is an art of converting plain data into unreadable format.
Steganography can be integrated with Cryptography in order to enhance the security of data.

Code:
clc
clear all
close all
warning off
a=imread('testimage.png');
nexttile;
imshow(a);
title('Carrier Image');
x=imread('SECRET.jpg');
nexttile;
imshow(x);
title('Secret Image');
[r c g]=size(a);
x=imresize(x,[r c]);
ra=a(:,:,1);
ga=a(:,:,2);
ba=a(:,:,3);
rx=x(:,:,1);
gx=x(:,:,2);
bx=x(:,:,3);
sk=uint8(rand(r,c)*255);%Secret key
rx=bitxor(rx,sk);
gx=bitxor(gx,sk);
bx=bitxor(bx,sk);
nexttile;
imshow(cat(3,rx,gx,bx));
title('Encrypted Secret Message');
for i=1:r
for j=1:c
nc(i,j)= bitand(ra(i,j),254);
ns(i,j)= bitand(rx(i,j),128);
ds(i,j)=ns(i,j)/128;
fr(i,j)=nc(i,j)+ds(i,j);
end
end
redsteg=fr;
for i=1:r
for j=1:c
nc(i,j)= bitand(ga(i,j),254);
ns(i,j)= bitand(gx(i,j),128);
ds(i,j)=ns(i,j)/128;
fr(i,j)=nc(i,j)+ds(i,j);
end
end
greensteg=fr;
for i=1:r
for j=1:c
nc(i,j)= bitand(ba(i,j),254);
ns(i,j)= bitand(bx(i,j),128);
ds(i,j)=ns(i,j)/128;
fr(i,j)=nc(i,j)+ds(i,j);
end
end
bluesteg=fr;
finalsteg=cat(3,redsteg,greensteg,bluesteg);
redstegr=finalsteg(:,:,1);
greenstegr=finalsteg(:,:,2);
bluestegr=finalsteg(:,:,3);
nexttile;
imshow(finalsteg);
title('Stegmented Image');
for i=1:r
for j=1:c
nc(i,j)=bitand(redstegr(i,j),1);
ms(i,j)=nc(i,j)*128;
end
end
recoveredr=ms;
for i=1:r
for j=1:c
nc(i,j)=bitand(greenstegr(i,j),1);
ms(i,j)=nc(i,j)*128;
end
end
recoveredg=ms;
for i=1:r
for j=1:c
nc(i,j)=bitand(bluestegr(i,j),1);
ms(i,j)=nc(i,j)*128;
end
end
recoveredb=ms;
output=cat(3,recoveredr,recoveredg,recoveredb);
nexttile;
imshow(output);
title('Recovered Encrypted Image from Steganography');
red_band=bitxor(output(:,:,1),sk);
green_band=bitxor(output(:,:,2),sk);
blue_band=bitxor(output(:,:,3),sk);
combined=cat(3,red_band,green_band,blue_band);
nexttile;
imshow(combined);
title('Decrypted secret message signal');

Prerequisite:
Secrets Hidden in Images (LSB based Steganography) | MATLAB
https://youtu.be/ZXfNhSlXT0w
nexttile documentation link--
https://in.mathworks.com/help/matlab/ref/nexttile.html
Learn Complete Machine Learning & Data Science using MATLAB:
https://www.youtube.com/playlist?list=PLjfRmoYoxpNoaZmR2OTVrh-72YzLZBlJ2

Learn Digital Signal Processing using MATLAB:
https://www.youtube.com/playlist?list=PLjfRmoYoxpNr3w6baU91ZM6QL0obULPig

Learn Complete Image Processing & Computer Vision using MATLAB:
https://www.youtube.com/playlist?list=PLjfRmoYoxpNostbIaNSpzJr06mDb6qAJ0



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