WATER-MARK ENCRYPTION AND DECRYPTION IN JAVA
Crypter.JAVA
import java.awt.Color;
public class Crypter {
private Picture copy;
private Picture key;
private int bytes;
private int countc; //count chars at text, when crypting
public Crypter(String key) {
this.key = new Picture(key);
copy = new Picture(key);
bytes = this.key.width() * this.key.height() - 2;
}
public String deCrypt(String file) {
if (file.length() < 1) {
return null;
}
copy = new Picture(file);
int allowed = deCalcAllowed(1, 1);
int count = 0;
String text = "";
for (int i = 0; i < key.width(); i++) {
for (int j = 0; j < key.height(); j++) {
if (!(i == 1 && j == 1)) {
count++;
if (count == allowed) {
text += deCryptChar(i, j);
count = 0;
}
}
}
}
return text;
}
public boolean encrypt(String text, String file) {
copy = new Picture(key.toString());
countc = 0;
int count = 0;
if (text.length() == 0) {
return false; // Nothing to encrypt
}
if (text.length() > bytes) {
return false; // The string is too long
}
int allowed = (int) Math.floor(bytes / text.length()); // bytes between characters. includes char.
allowed(allowed, 1, 1);
//int badData = (int)Math.floor(bytes/allowed)-text.length();
try {
for (int i = 0; i < key.width(); i++) {
for (int j = 0; j < key.height(); j++) {
if (!(i == 1 && j == 1)) {
count++;
if (count == allowed) {
cryptChar(i, j, next(text));
count = 0;
} else {
cryptChar(i, j, 0);
}
}
}
}
copy.save(file);
} catch (Exception e) {
System.out.println("I'm sorry, something went wrong, probably invalid character, try using characters present in 8-bit ASCII");
return false;
}
return true;
}
private char deCryptChar(int x, int y) {
Color d = difference(x, y);
int a = d.getRed() + d.getGreen() + d.getBlue();
return (char) a;
}
private void cryptChar(int x, int y, int a) {
Color pix = key.get(x, y);
int blue = pix.getBlue();
int red = pix.getRed();
int green = pix.getGreen();
if (a == 0) {
int intensity = 30; // close to 40 is most secure
int r = (int) (Math.random() * intensity);
if (blue >= 128) {
blue -= r;
} else {
blue += r;
}
r = (int) (Math.random() * intensity);
if (green >= 128) {
green -= r;
} else {
green += r;
}
r = (int) (Math.random() * intensity);
if (red >= 128) {
red -= r;
} else {
red += r;
}
} else {
Coord c = split3(a);
int r = c.x;
if (blue >= 128) {
blue -= r;
} else {
blue += r;
}
r = c.y;
if (green >= 128) {
green -= r;
} else {
green += r;
}
r = c.z;
if (red >= 128) {
red -= r;
} else {
red += r;
}
}
pix = new Color(red, green, blue);
copy.set(x, y, pix);
}
private int next(String text) {
char a = 0;
if (text.length() > countc) {
a = text.charAt(countc);
countc++;
}
return a;
}
private void allowed(int allowed, int x, int y) {
Color pix = key.get(x, y);
int blue = pix.getBlue();
int red = pix.getRed();
int green = pix.getGreen();
int count = 0;
while (allowed > 127) {
count++;
allowed -= 127;
}
if (count > 0) {
Coord e = split2(count);
if (red < 128) {
red += e.x;
} else {
red -= e.x;
}
if (green < 128) {
green += e.y;
} else {
green -= e.y;
}
}
if (allowed <= 127) {
if (blue < 128) {
blue += allowed;
} else if (blue >= 128) {
blue -= allowed;
}
}
pix = new Color(red, green, blue);
copy.set(x, y, pix);
}
private int deCalcAllowed(int x, int y) {
Color d = difference(x, y);
return (d.getRed() * 127 + d.getGreen() * 127) + d.getBlue();
}
private Color difference(int x, int y) {
Color pix = key.get(x, y);
int blue = pix.getBlue();
int red = pix.getRed();
int green = pix.getGreen();
Color c = copy.get(x, y);
int Cblue = c.getBlue();
int Cred = c.getRed();
int Cgreen = c.getGreen();
return new Color(Math.abs(red - Cred), Math.abs(green - Cgreen), Math.abs(blue - Cblue));
}
private Coord split2(int a) {
int r = (int) (Math.random() * a);
a -= r;
Coord c = new Coord(a, r);
return c;
}
private Coord split3(int a) {
int z = 0;
int r = (int) (Math.random() * a);
a -= r;
if (a > r) {
z = (int) (Math.random() * a);
a -= z;
} else {
z = (int) (Math.random() * r);
r -= z;
}
Coord c = new Coord(a, r, z);
return c;
}
}
class Coord {
public int x;
public int y;
public int z;
public Coord(int x, int y) {
this.x = x;
this.y = y;
}
public Coord(int x, int y, int z) {
this.x = x;
this.y = y;
this.z = z;
}
}
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public class Test
{
public static void main(String[] args) {
Crypter c = new Crypter("key.PNG"); // Key picture.
//Crypt
c.encrypt("JAVA stegnography tech..", "secret.PNG");
//Decrypt
System.out.println(c.deCrypt("Secret.PNG"));
}
}
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ORIGINAL IMAGE WITHOUT ANY ENCRYPTION:
SECRET IMAGE WITH ENCRYPTION WORD "JAVA stegnography tech."
