Develop Reference

How to encrypt and decrypt tensorflow model in android successfully

As files in android assets can be easily hacked by converting .apk to .zip. I have some propitiatory model which I need to use in android application. I am working on how to encrypt the assets of the application. ( I will use firebase for retreiving the key for decryption to make it more secure )
I am pretty successful in encrypting and decrypting images (png and jpg) using cipher library in android.
Following is the code which I used for the purpose.
String fake = "sadhkja6";
byte[] encodedKey = Base64.decode(fake, Base64.DEFAULT);
yourKey= new SecretKeySpec(encodedKey, 0, encodedKey.length, "AES");
Bitmap bitmap = BitmapFactory.decodeResource(getResources(), id);
bitmap = Bitmap.createScaledBitmap(bitmap, 500,500, true);
byte[] output = getBytes(bitmap);
byte[] output = getBytesFile();
saveFile(output);
public static byte[] encodeFile(SecretKey yourKey, byte[] fileData)
throws Exception {
byte[] encrypted = null;
byte[] data = yourKey.getEncoded();
SecretKeySpec skeySpec = new SecretKeySpec(data, 0, data.length,
algorithm);
Cipher cipher = Cipher.getInstance(algorithm);
cipher.init(Cipher.ENCRYPT_MODE, skeySpec, new IvParameterSpec(
new byte[cipher.getBlockSize()]));
encrypted = cipher.doFinal(fileData);
return encrypted;
}
public byte[] getBytes(Bitmap bitmap){
ByteArrayOutputStream stream = new ByteArrayOutputStream();
bitmap.compress( Bitmap.CompressFormat.PNG, 100, stream);
byte[] byteArray = stream.toByteArray();
bitmap.recycle();
return byteArray;
}
public static byte[] encodeFile(SecretKey yourKey, byte[] fileData)
throws Exception {
byte[] encrypted = null;
byte[] data = yourKey.getEncoded();
SecretKeySpec skeySpec = new SecretKeySpec(data, 0, data.length,
algorithm);
Cipher cipher = Cipher.getInstance(algorithm);
cipher.init(Cipher.ENCRYPT_MODE, skeySpec, new IvParameterSpec(
new byte[cipher.getBlockSize()]));
encrypted = cipher.doFinal(fileData);
return encrypted;
}
void saveFile(byte[] array) {
String decrypted_file = "encypted.png";
try {
File file = new File(Environment.getExternalStorageDirectory()
+ File.separator, decrypted_file);
BufferedOutputStream bos = new BufferedOutputStream(
new FileOutputStream(file));
yourKey = generateKey();
byte[] filesBytes = encodeFile(yourKey, array);
bos.write(filesBytes);
bos.flush();
bos.close();
} catch (FileNotFoundException e) {
e.printStackTrace();
} catch (IOException e) {
e.printStackTrace();
} catch (Exception e) {
e.printStackTrace();
}
}
But when I use the same code for encyrpting tensorflow models, the model is not successfully decompiled resulting in app crash. Most probably because we are loading the model in bytes which may cause problems.
Please tell me how can I use the cyphering technique for securing my tensorflow model. Thank you very much.

how to encrypt and decrypt audio file android

I am trying to encrypt and then decrypt audio file . Everything goes right but when I try to decrypt the encrypted audio , everytime I got this exception
javax.crypto.BadPaddingException: pad block corrupted
My MainActivity is like this: I want to decrypt and play the song side by side
public class MainActivity extends Activity{
private final String KEY = "abc";
Button btn_Dec, btn_In;
byte[] incrept;
byte[] decrpt;
#Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
ctx = this;
btn_Dec = (Button) findViewById(R.id.button2);
btn_In = (Button) findViewById(R.id.button1);
btn_Dec.setOnClickListener(btnDecListner);
btn_In.setOnClickListener(btnInListner);
}
public OnClickListener btnDecListner = new OnClickListener() {
public void onClick(View v) {
VincentFileCrypto simpleCrypto = new VincentFileCrypto();
try {
// decrypt the file here first argument is key and second is encrypted file which we get from SD card.
decrpt = simpleCrypto.decrypt(KEY, getAudioFileFromSdCard());
//play decrypted audio file.
playMp3(decrpt);
} catch (Exception e) {
e.printStackTrace();
}
}
};
Context ctx;
public OnClickListener btnInListner = new OnClickListener() {
public void onClick(View v) {
VincentFileCrypto simpleCrypto = new VincentFileCrypto();
try {
// encrypt audio file send as second argument and corresponding key in first argument.
incrept = simpleCrypto.encrypt(KEY, getAudioFile());
//Store encrypted file in SD card of your mobile with name vincent.mp3.
FileOutputStream fos = new FileOutputStream(new File("/sdcard/vincent.mp3"));
fos.write(incrept);
fos.close();
} catch (Exception e) {
e.printStackTrace();
}
}
};
/**
* #return byte array for encryption.
* #throws FileNotFoundException
*/
public byte[] getAudioFile() throws FileNotFoundException
{
byte[] audio_data = null;
byte[] inarry = null;
AssetManager am = ctx.getAssets();
try {
InputStream is = am.open("Sleep Away.mp3"); // use recorded file instead of getting file from assets folder.
int length = is.available();
audio_data = new byte[length];
int bytesRead;
ByteArrayOutputStream output = new ByteArrayOutputStream();
while ((bytesRead = is.read(audio_data)) != -1)
{
output.write(audio_data, 0, bytesRead);
}
inarry = output.toByteArray();
} catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
return inarry;
}
/**
* This method fetch encrypted file which is save in sd card and convert it in byte array after that this file will be decrept.
*
* #return byte array of encrypted data for decription.
* #throws FileNotFoundException
*/
public byte[] getAudioFileFromSdCard() throws FileNotFoundException
{
byte[] inarry = null;
try {
//getting root path where encrypted file is stored.
File sdcard = Environment.getExternalStorageDirectory();
File file = new File(sdcard, "vincent.mp3"); //Creating file object
//Convert file into array of bytes.
FileInputStream fileInputStream = null;
byte[] bFile = new byte[(int) file.length()];
fileInputStream = new FileInputStream(file);
fileInputStream.read(bFile);
fileInputStream.close();
inarry = bFile;
} catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
return inarry;
}
/**
* This Method is used to play audio file after decrepting.
*
* #param mp3SoundByteArray : This is our audio file which will be play and it converted in byte array.
*/
private void playMp3(byte[] mp3SoundByteArray) {
try {
// create temp file that will hold byte array
File tempMp3 = File.createTempFile("kurchina", "mp3", getCacheDir());
tempMp3.deleteOnExit();
FileOutputStream fos = new FileOutputStream(tempMp3);
fos.write(mp3SoundByteArray);
fos.close();
// Tried reusing instance of media player
// but that resulted in system crashes...
MediaPlayer mediaPlayer = new MediaPlayer();
FileInputStream fis = new FileInputStream(tempMp3);
mediaPlayer.setDataSource(fis.getFD());
mediaPlayer.prepareAsync();
mediaPlayer.start();
} catch (IOException ex) {
ex.printStackTrace();
}
}
}
The encryption and decryption methods are mentioned in this class
public class VincentFileCrypto {
public byte[] encrypt(String seed, byte[] cleartext) throws Exception {
byte[] rawKey = getRawKey(seed.getBytes());
byte[] result = encrypt(rawKey, cleartext);
// return toHex(result);
return result;
}
public byte[] decrypt(String seed, byte[] encrypted) throws Exception {
byte[] rawKey = getRawKey(seed.getBytes());
byte[] enc = encrypted;
byte[] result = decrypt(rawKey, enc);
return result;
}
//done
private byte[] getRawKey(byte[] seed) throws Exception {
KeyGenerator kgen = KeyGenerator.getInstance("AES");
SecureRandom sr = SecureRandom.getInstance("SHA1PRNG");
sr.setSeed(seed);
kgen.init(128, sr); // 192 and 256 bits may not be available
SecretKey skey = kgen.generateKey();
byte[] raw = skey.getEncoded();
return raw;
}
private byte[] encrypt(byte[] raw, byte[] clear) throws Exception {
SecretKeySpec skeySpec = new SecretKeySpec(raw, "AES");
Cipher cipher = Cipher.getInstance("AES");
cipher.init(Cipher.ENCRYPT_MODE, skeySpec);
byte[] encrypted = cipher.doFinal(clear);
return encrypted;
}
private byte[] decrypt(byte[] raw, byte[] encrypted) throws Exception {
SecretKeySpec skeySpec = new SecretKeySpec(raw, "AES");
Cipher cipher = Cipher.getInstance("AES");
cipher.init(Cipher.DECRYPT_MODE, skeySpec);
byte[] decrypted = cipher.doFinal(encrypted);
return decrypted;
}
}

After days of research and hard work I found the solution ,may help and save somebody's else time . Here is my answer. I changed the above code logic like this
now what is happening , I am able to successfully encrypt the file and save it in the sdcard and then decrypt it to play . No body else can play the audio.
here we go : happy coding
public class Main2Activity extends AppCompatActivity {
private String encryptedFileName = "encrypted_Audio.mp3";
private static String algorithm = "AES";
static SecretKey yourKey = null;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main2);
//saveFile("Hello From CoderzHeaven asaksjalksjals");
try {
saveFile(getAudioFile());
} catch (FileNotFoundException e) {
e.printStackTrace();
}
decodeFile();
}
public static SecretKey generateKey(char[] passphraseOrPin, byte[] salt) throws NoSuchAlgorithmException, InvalidKeySpecException {
// Number of PBKDF2 hardening rounds to use. Larger values increase
// computation time. You should select a value that causes computation
// to take >100ms.
final int iterations = 1000;
// Generate a 256-bit key
final int outputKeyLength = 256;
SecretKeyFactory secretKeyFactory = SecretKeyFactory.getInstance("PBKDF2WithHmacSHA1");
KeySpec keySpec = new PBEKeySpec(passphraseOrPin, salt, iterations, outputKeyLength);
SecretKey secretKey = secretKeyFactory.generateSecret(keySpec);
return secretKey;
}
public static SecretKey generateKey() throws NoSuchAlgorithmException {
// Generate a 256-bit key
final int outputKeyLength = 256;
SecureRandom secureRandom = new SecureRandom();
// Do *not* seed secureRandom! Automatically seeded from system entropy.
KeyGenerator keyGenerator = KeyGenerator.getInstance("AES");
keyGenerator.init(outputKeyLength, secureRandom);
yourKey = keyGenerator.generateKey();
return yourKey;
}
public static byte[] encodeFile(SecretKey yourKey, byte[] fileData)
throws Exception {
byte[] encrypted = null;
byte[] data = yourKey.getEncoded();
SecretKeySpec skeySpec = new SecretKeySpec(data, 0, data.length, algorithm);
Cipher cipher = Cipher.getInstance(algorithm);
cipher.init(Cipher.ENCRYPT_MODE, skeySpec, new IvParameterSpec(
new byte[cipher.getBlockSize()]));
encrypted = cipher.doFinal(fileData);
return encrypted;
}
public static byte[] decodeFile(SecretKey yourKey, byte[] fileData)
throws Exception {
byte[] decrypted = null;
Cipher cipher = Cipher.getInstance(algorithm);
cipher.init(Cipher.DECRYPT_MODE, yourKey, new IvParameterSpec(new byte[cipher.getBlockSize()]));
decrypted = cipher.doFinal(fileData);
return decrypted;
}
void saveFile(byte[] stringToSave) {
try {
File file = new File(Environment.getExternalStorageDirectory() + File.separator, encryptedFileName);
BufferedOutputStream bos = new BufferedOutputStream(new FileOutputStream(file));
yourKey = generateKey();
byte[] filesBytes = encodeFile(yourKey, stringToSave);
bos.write(filesBytes);
bos.flush();
bos.close();
} catch (FileNotFoundException e) {
e.printStackTrace();
} catch (IOException e) {
e.printStackTrace();
} catch (Exception e) {
e.printStackTrace();
}
}
void decodeFile() {
try {
byte[] decodedData = decodeFile(yourKey, readFile());
// String str = new String(decodedData);
//System.out.println("DECODED FILE CONTENTS : " + str);
playMp3(decodedData);
} catch (Exception e) {
e.printStackTrace();
}
}
public byte[] readFile() {
byte[] contents = null;
File file = new File(Environment.getExternalStorageDirectory()
+ File.separator, encryptedFileName);
int size = (int) file.length();
contents = new byte[size];
try {
BufferedInputStream buf = new BufferedInputStream(
new FileInputStream(file));
try {
buf.read(contents);
buf.close();
} catch (IOException e) {
e.printStackTrace();
}
} catch (FileNotFoundException e) {
e.printStackTrace();
}
return contents;
}
public byte[] getAudioFile() throws FileNotFoundException
{
byte[] audio_data = null;
byte[] inarry = null;
AssetManager am = getAssets();
try {
InputStream is = am.open("Sleep Away.mp3"); // use recorded file instead of getting file from assets folder.
int length = is.available();
audio_data = new byte[length];
int bytesRead;
ByteArrayOutputStream output = new ByteArrayOutputStream();
while ((bytesRead = is.read(audio_data)) != -1) {
output.write(audio_data, 0, bytesRead);
}
inarry = output.toByteArray();
} catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
return inarry;
}
private void playMp3(byte[] mp3SoundByteArray) {
try {
// create temp file that will hold byte array
File tempMp3 = File.createTempFile("kurchina", "mp3", getCacheDir());
tempMp3.deleteOnExit();
FileOutputStream fos = new FileOutputStream(tempMp3);
fos.write(mp3SoundByteArray);
fos.close();
// Tried reusing instance of media player
// but that resulted in system crashes...
MediaPlayer mediaPlayer = new MediaPlayer();
FileInputStream fis = new FileInputStream(tempMp3);
mediaPlayer.setDataSource(fis.getFD());
mediaPlayer.prepare();
mediaPlayer.start();
} catch (IOException ex) {
ex.printStackTrace();
}
}
}

Android Lollipop Decryption using AES is not working properly

Till kitkat, encryption/decryption is working good but in lollipop it decrypts only partial data.
I don't have problem with encryption because I encrypted a file with lollipop and decrypts it with kitkat it works fine but not vice versa.
Here is the code.
Encryption code
Encrypt(BufferedInputStream is, File destfile, String passcode) {
bis = is;
try {
fos = new FileOutputStream(destfile);
} catch (FileNotFoundException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
dest = new BufferedOutputStream(fos, 1024);
this.passcode = passcode;
}
static void encrypt() throws IOException, NoSuchAlgorithmException,
NoSuchPaddingException, InvalidKeyException {
// Length is 16 byte
SecretKeySpec sks = new SecretKeySpec(passcode.getBytes(), "AES");
// Create cipher
Cipher cipher = Cipher.getInstance("AES");
cipher.init(Cipher.ENCRYPT_MODE, sks);
// Wrap the output stream
CipherOutputStream cos = new CipherOutputStream(fos, cipher);
// Write bytes
int b;
byte[] d = new byte[1024];
while ((b = bis.read(d)) != -1) {
cos.write(d, 0, b);
}
// Flush and close streams.
cos.flush();
cos.close();
bis.close();
}
Decryption code
public Decrypt(String path, String pathcode) {
// TODO Auto-generated constructor stub
filepath = path;
try {
fis = new FileInputStream(new File(path));
this.passcode = pathcode;
} catch (FileNotFoundException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
static String decrypt() throws IOException, NoSuchAlgorithmException,
NoSuchPaddingException, InvalidKeyException {
SecretKeySpec sks = new SecretKeySpec(passcode.getBytes(), "AES");
Cipher cipher = Cipher.getInstance("AES");
cipher.init(Cipher.DECRYPT_MODE, sks);
CipherInputStream cis = new CipherInputStream(fis, cipher);
int size = fis.available();
byte[] resdata = new byte[size];
cis.read(resdata, 0, size);
String newres = new String(resdata, "UTF-8").trim();
//write("decrypted_file.xhtml",newres);
if(fis!=null)
{
fis.close();
}
if(cis!=null)
cis.close();
return newres;
}
What's the problem in this code? Do I need to do anything more?

available() doesn't necessarily return the length of the entire stream, just the estimated number of bytes that can be read without blocking. So, use a ByteArrayOutputStream to store the bytes and then covert to a byte array:
CipherInputStream cis = new CipherInputStream(fis, cipher);
ByteArrayOutputStream buffer = new ByteArrayOutputStream();
int bytesRead;
byte[] data = new byte[1024];
while ((bytesRead = cis.read(data, 0, data.length)) != -1) {
buffer.write(data, 0, bytesRead);
}
buffer.flush();
byte[] resdata = buffer.toByteArray();
String newres = new String(resdata, "UTF-8").trim();

Decrypt AES256 encrypted bytes

I've never worked with encryption before. Actually I know nothing about encryption. I have a file encrypted with openssl tool using params:
openssl aes-256-cbc -nosalt -in fileIn -out fileOUT -p -k KEY
I need to decrypt it into memory but I don't know how. Can anyone provide me the code related to encryption?

Here's class I have written to decrypt a string encoded with params above (if I remmeber it correct):
public class CipherUtils {
public static byte[] getKey(String password, byte[] salt) {
try {
byte[] passwordSalt = EncodingUtils.getAsciiBytes(password);
passwordSalt = concatenateByteArrays(passwordSalt, salt);
byte[] hash1 = getHashForHash(null, passwordSalt);
byte[] hash2 = getHashForHash(hash1, passwordSalt);
byte[] key = concatenateByteArrays(hash1, hash2);
return key;
} catch (Exception e) {
return null;
}
}
public static byte[] getIV(String password, byte[] salt) {
try {
byte[] passwordSalt = EncodingUtils.getAsciiBytes(password);
passwordSalt = concatenateByteArrays(passwordSalt, salt);
byte[] hash1 = getHashForHash(null, passwordSalt);
byte[] hash2 = getHashForHash(hash1, passwordSalt);
byte[] hash3 = getHashForHash(hash2, passwordSalt);
return hash3;
} catch (Exception e) {
return null;
}
}
private static byte[] getHashForHash(byte[] hash, byte[] passwordSalt) {
try {
byte[] hashMaterial = concatenateByteArrays(hash, passwordSalt);
MessageDigest md = MessageDigest.getInstance("MD5");
return md.digest(hashMaterial);
} catch (Exception e) {
return null;
}
}
private static byte[] concatenateByteArrays(byte[] a, byte[] b) {
if (a == null)
return b;
if (b == null)
return a;
byte[] result = new byte[a.length + b.length];
System.arraycopy(a, 0, result, 0, a.length);
System.arraycopy(b, 0, result, a.length, b.length);
return result;
}
}
Salt is an empty bytearray in this case. It uses apache-commons-compress.jar.
Here's usage example:
byte[] key = CipherUtils.getKey(password, null);
byte[] IV = CipherUtils.getIV(password, null);
Cipher cipher = Cipher.getInstance("AES/CBC/PKCS5Padding");
cipher.init(Cipher.DECRYPT_MODE, new SecretKeySpec(key, "AES"),
new IvParameterSpec(IV));
cis = new CipherInputStream(is, cipher);
Where is is an InputStream of encrypted data.

this may helps you
public void encrypt() throws IOException, NoSuchAlgorithmException, NoSuchPaddingException, InvalidKeyException {
// Here you read the cleartext.
FileInputStream fis = new FileInputStream("data/cleartext");
// This stream write the encrypted text. This stream will be wrapped by
// another stream.
FileOutputStream fos = new FileOutputStream("data/encrypted");
// Length is 16 byte
SecretKeySpec sks = new SecretKeySpec("yourkey".getBytes(), "AES");
// Create cipher
Cipher cipher = Cipher.getInstance("AES/CBC");
cipher.init(Cipher.ENCRYPT_MODE, sks);
// Wrap the output stream
CipherOutputStream cos = new CipherOutputStream(fos, cipher);
// Write bytes
int b;
byte[] d = new byte[8];
while ((b = fis.read(d)) != -1) {
cos.write(d, 0, b);
}
// Flush and close streams.
cos.flush();
cos.close();
fis.close();
}
Decrypt
public void decrypt() throws IOException, NoSuchAlgorithmException, NoSuchPaddingException, InvalidKeyException {
FileInputStream fis = new FileInputStream("data/encrypted");
FileOutputStream fos = new FileOutputStream("data/decrypted");
SecretKeySpec sks = new SecretKeySpec("yourkey".getBytes(), "AES");
Cipher cipher = Cipher.getInstance("AES/CBC");
cipher.init(Cipher.DECRYPT_MODE, sks);
CipherInputStream cis = new CipherInputStream(fis, cipher);
int b;
byte[] d = new byte[8];
while((b = cis.read(d)) != -1) {
fos.write(d, 0, b);
}
fos.flush();
fos.close();
cis.close();
}

AES decryption and encryption issue

I have done an encryption using the AES but iam not able to do the decryption Iam gettin an javax.crypto.IllegalBlockSizeException: last block incomplete in decryption.....I cant trace out where is the problem.I appreciate any help.
try {
in = new FileInputStream("/sdcard/Pic 1.txt");
} catch (FileNotFoundException e) {
e.printStackTrace();
}
File f=new File("/sdcard/Pic 1.txt");
buf = new byte[(int) f.length()+2];
try {
in.read(buf);
} catch (IOException e) {
e.printStackTrace();
}
try {
decryptedData = decrypt(key, buf);
decryptedimage = BitmapFactory.decodeByteArray(
decryptedData, 0, decryptedData.length);
loadedimage.setImageBitmap(decryptedimage);
} catch (Exception e) {
e.printStackTrace();
}
}
});
}
public void Encription(Bitmap bm) {
ByteArrayOutputStream baos = new ByteArrayOutputStream();
bm.compress(Bitmap.CompressFormat.JPEG, 100, baos);
b = baos.toByteArray();
try {
keyStart = ".....".getBytes();
kgen = KeyGenerator.getInstance("AES");
sr = SecureRandom.getInstance("SHA1PRNG");
sr.setSeed(keyStart);
kgen.init(128, sr); // 192 and 256 bits may not be available
skey = kgen.generateKey();
key = skey.getEncoded();
encryptedData = encrypt(key, b);
encryptedimage = BitmapFactory.decodeByteArray(encryptedData, 0,
encryptedData.length);
out = new FileOutputStream("/sdcard/"+"Pic "+i+".txt");
out.write(encryptedData, 0, encryptedData.length);
out.close();
} catch (Exception e) {
}
i++;
}
private byte[] encrypt(byte[] raw, byte[] clear) throws Exception {
SecretKeySpec skeySpec = new SecretKeySpec(raw, "AES");
Cipher cipher = Cipher.getInstance("AES");
cipher.init(Cipher.ENCRYPT_MODE, skeySpec);
byte[] encrypted = cipher.doFinal(clear);
return encrypted;
}
private byte[] decrypt(byte[] raw, byte[] encrypted) throws Exception {
long start=System.currentTimeMillis()/1000l;
SecretKeySpec skeySpec = new SecretKeySpec(raw, "AES");
Cipher cipher = Cipher.getInstance("AES");
cipher.init(Cipher.DECRYPT_MODE, skeySpec);
byte[] decrypted = cipher.doFinal(encrypted);
return decrypted;
}
02-19 08:27:06.972: W/System.err(12742): javax.crypto.IllegalBlockSizeException: last block incomplete in decryption