Video encryption for offline playing In Android - offline

Question

I want to download mp4 video from server to my Android Device. I want this video to be stored in chunks(encrypted) and should combine in real time when video plays. How to start working on this.

Answer 1

For Sample like that
public class AESdemo extends Activity {
boolean encryptionIsOn = true;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_aesdemo);
// needs <uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE" />
String homeDirName = Environment.getExternalStorageDirectory().getAbsolutePath() +
"/" + getPackageName();
File file = new File(homeDirName, "test.txt");
byte[] keyBytes = getKey("password");
try {
File dir = new File(homeDirName);
if (!dir.exists())
dir.mkdirs();
if (!file.exists())
file.createNewFile();
OutputStreamWriter osw;
if (encryptionIsOn) {
Cipher cipher = Cipher.getInstance("AES/CBC/PKCS5Padding");
SecretKeySpec secretKeySpec = new SecretKeySpec(keyBytes, "AES");
IvParameterSpec ivParameterSpec = new IvParameterSpec(keyBytes);
cipher.init(Cipher.ENCRYPT_MODE, secretKeySpec, ivParameterSpec);
FileOutputStream fos = new FileOutputStream(file);
CipherOutputStream cos = new CipherOutputStream(fos, cipher);
osw = new OutputStreamWriter(cos, "UTF-8");
}
else // not encryptionIsOn
osw = new FileWriter(file);
BufferedWriter out = new BufferedWriter(osw);
out.write("This is a test\n");
out.close();
}
catch (Exception e) {
System.out.println("Encryption Exception "+e);
}
///////////////////////////////////
try {
InputStreamReader isr;
if (encryptionIsOn) {
Cipher cipher = Cipher.getInstance("AES/CBC/PKCS5Padding");
SecretKeySpec secretKeySpec = new SecretKeySpec(keyBytes, "AES");
IvParameterSpec ivParameterSpec = new IvParameterSpec(keyBytes);
cipher.init(Cipher.DECRYPT_MODE, secretKeySpec, ivParameterSpec);
FileInputStream fis = new FileInputStream(file);
CipherInputStream cis = new CipherInputStream(fis, cipher);
isr = new InputStreamReader(cis, "UTF-8");
}
else
isr = new FileReader(file);
BufferedReader in = new BufferedReader(isr);
String line = in.readLine();
System.out.println("Text read: <"+line+">");
in.close();
}
catch (Exception e) {
System.out.println("Decryption Exception "+e);
}
}
private byte[] getKey(String password) throws UnsupportedEncodingException {
String key = "";
while (key.length() < 16)
key += password;
return key.substring(0, 16).getBytes("UTF-8");
}
}
Instead of text file use .mp4