Hiding a Text Message in a Sound 'java"

//This project will use a technique called "steganography" to encode a text message. Steganography is
//basically hiding one set of data within another set of data.
//For this project we want to take an ascii text message and hide it into the a sound file. We will also want to
//be able to extract the message. For this we will need to write one program that can either encode a text
 //message into a sound or extract a message from a sound. Your program will first first prompt the user to
 //enter the value of either 1 or 2. If the user enters a 1, your program is to perform the encoding.


/**
*/
public class Project

{

public static void main(String[] args) {
// Ask user for what to do
int select = SimpleInput.getIntNumber("what would you like to execute?\n\n1: Encrypt a text message into sound\n2: Extract a text message from a sound");
if (select == 1) {
// Hide The Message
String inputFile = FileChooser.pickAFile();
// prompt user for a file
String message = SimpleInput.getString("Type the message you want to hide in the sound file:");
String outputFile = SimpleInput.getString("Filename of modified sound: ");
encodeSound(inputFile, outputFile, message);
// Encrypt message in inputFile and save it to outputFile
} else if (select == 2) {
// get the hidden text message from file
String inputFile = FileChooser.pickAFile();
decodeMessage(inputFile); // Decode the message in inputFile
} else {
System.exit(1); // Exits if any other digit is input
}
}

// Hides a text message in a sound file.
public static void encodeSound(String inputFile, String outputFile, String message)
{
// Create the sound file
Sound s = new Sound(inputFile);
int nbrOfSamples = message.length() * 3;
// Calculate the number of samples needed for the message including the terminating null character
smoothAmpValues(s, nbrOfSamples + 3);
// Set the one's of the amplitude values to zero.

for (int g = 0; g < nbrOfSamples; g++) {
// Iterate over all samples needed
int asciiValue = (int) message.charAt(g / 3);
// Acquire ascii value for the current character
int digit = getDecimalDigit(asciiValue, g % 3);
// Acquire next digit to encode
int ampValue;
if (s.getSampleValueAt(g) >= 0)
{
// If amplitude is positive
ampValue = s.getSampleValueAt(g) + digit; // then add new value
}
else
{ // If amplitude is negative
ampValue = s.getSampleValueAt(g) - digit; // then subtract new value
}
// Special cases
if (ampValue > 32767)
{
ampValue = ampValue - 10;
}
if (ampValue < -32768)
{
ampValue = ampValue + 10;
}

s.setSampleValueAt(g, ampValue); // Replace amplitude value in the sound object
}
try {
s.writeToFile(outputFile+".wav");
// Save the encoded sound file
} catch (SoundException e) {
e.printStackTrace();
}
System.exit(0);
// Exit program
}

// start a method to set the one's didgit in the frst sample to zero.
public static void smoothAmpValues(Sound s, int nbrOfSamples)
{
for (int g = 0; g < nbrOfSamples; g++) {
int ampValue = s.getSampleValueAt(g);
int modAmpValue = ampValue - ampValue % 10;
// Set one's digit to zero
s.setSampleValueAt(g, modAmpValue);
// Replace amplitude value in sound object
}
}

// start a method to get certain digit from an integer (asciicode =)
public static int getDecimalDigit (int asciiCode, int decimalDigitPosition) {
for (int i = 0; i < decimalDigitPosition; i++) {
asciiCode = asciiCode / 10;
}
return Math.abs(asciiCode % 10);
}

//start a method to decode the message.
public static void decodeMessage(String filename) {
Sound s = new Sound(filename);
// Create sound file
SoundSample[] samples = s.getSamples();
// Acquire the samples from the sound file
int[] digit = new int[3];
// collection containing the three digits of an ascii code
String message = "";
int sampleIndex = 0;
boolean nullReached = false;

while (!nullReached) {
digit[0] = getDecimalDigit(samples[sampleIndex].getValue(), 0); // Acquire the digits
digit[1] = getDecimalDigit(samples[sampleIndex + 1].getValue(), 0);
digit[2] = getDecimalDigit(samples[sampleIndex + 2].getValue(), 0);
int asciiValue = digit[0] + digit[1] * 10 + digit[2] * 100; // and change to the ascii code

if (digit[0] == digit[1] && digit[1] == digit[2] && digit[2] == 0)
// Exit if null character is reached
nullReached = true;
message += (char) asciiValue;
// Attach the next hidden character to the message string
sampleIndex += 3;
if (sampleIndex > samples.length - 1) {
// Print error message and end program if null character is never reached
SimpleOutput.showError("Null character never reached. Possible reason: no hidden text in file.");
System.exit(1);
}
}
SimpleOutput.showInformation(message); // Display the hidden message.
System.exit(0);
}

}