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chameleon.m
145 lines (89 loc) · 2.68 KB
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chameleon.m
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%% Program variables.
clc, clear;
modes = [
"LSB encode"
"LSB decode"
];
num_modes = max(size(modes));
% Constants.
HEAD_LEN = 64;
BYTE_LEN = 8;
STEG_IMG = "steg.png";
%% Prompt user for mode of operation.
fprintf("Modes available:\n");
% Print available modes.
for i = 1 : num_modes
fprintf("%d) %s\n", i, modes(i));
end
fprintf("\n");
mode = -1;
% Prompt user for desired mode.
while ~(1 <= mode && mode <= num_modes)
mode = input("Run steganography in mode: ");
end
fprintf("\n\n");
%% Operation: encode.
if mode == 1
fprintf("Mode %d: %s\n", mode, modes(mode));
fprintf("------------------\n");
img_filename = "";
bin_filename = "";
% Prompt user for image filename.
while ~isfile(img_filename)
img_filename = input("img file: ", "s");
end
% Prompt user for binary filename.
while ~isfile(bin_filename)
bin_filename = input("bin file: ", "s");
end
fprintf("\n");
% Load files onto stack.
img = imread(img_filename);
bin_fd = fopen(bin_filename, "r");
bin_data = fread(bin_fd);
fclose(bin_fd);
% Construct payload.
num_bytes = max(size(bin_data));
head = serialize(num_bytes, HEAD_LEN);
body = serialize(bin_data , BYTE_LEN);
payload = [head, body];
% Embed binary file in image.
fprintf("Embedding binary file in image...");
mod_img = embed(img, payload);
fprintf(" done!\n");
% Save modified image.
fprintf("Saving modified image as %s...", STEG_IMG);
imwrite(mod_img, STEG_IMG);
fprintf(" done!\n\n");
end
%% Operation: decode.
if mode == 2
fprintf("Mode %d: %s\n", mode, modes(mode));
fprintf("------------------\n");
img_filename = "";
out_filename = "";
% Prompt user for image filename.
while ~isfile(img_filename)
img_filename = input("img file: ", "s");
end
% Prompt user for output filename.
out_filename = input("out file: ", "s");
fprintf("\n");
% Load files onto stack.
img = imread(img_filename);
% Extract payload from image.
fprintf("Extracting binary file from image...");
head = extract(img, 1, HEAD_LEN);
num_bytes = deserialize(head, HEAD_LEN);
from = HEAD_LEN + 1;
to = from + (num_bytes * 8 - 1);
body = extract(img, from, to);
bin_data = deserialize(body, BYTE_LEN);
fprintf(" done!\n");
% Recover original binary file.
fprintf("Writing binary file to %s...", out_filename);
bin_fd = fopen(out_filename, "w");
fwrite(bin_fd, bin_data);
fclose(bin_fd);
fprintf(" done!\n\n");
end