I am creating an application with content security for no one could ever copy the contents and files. I am using cipher to encrypt the image directly from the URL, with out downloading to the device. Please find my code below.
URL url = new URL(images.getImageurl()); HttpURLConnection connection = (HttpURLConnection) url.openConnection(); connection.setRequestMethod("GET"); connection.setDoOutput(true); File folder = new File(Environment.getExternalStorageDirectory(), "zerb"); boolean success = true; if (!folder.exists()){ folder.mkdirs(); } InputStream fis = connection.getInputStream(); String path = folder.getAbsolutePath() + "images.getImageName + ".jpg"; encryptfile(fis, path, AppConstants.password + images.getContentid() + images.getTopicid()) fis.close(); And the cipher encryption Method code is
private static boolean encryptfile(InputStream inputStream, String path, String password) throws IOException, NoSuchAlgorithmException, NoSuchPaddingException, InvalidKeyException { FileOutputStream fos = new FileOutputStream(path.concat(".crypt")); byte[] key = (AppConstants.salt + password).getBytes("UTF-8"); MessageDigest sha = MessageDigest.getInstance("SHA-1"); key = sha.digest(key); key = Arrays.copyOf(key, 16); SecretKeySpec sks = new SecretKeySpec(key, "AES"); Cipher cipher = Cipher.getInstance("AES"); cipher.init(Cipher.ENCRYPT_MODE, sks); CipherOutputStream cos = new CipherOutputStream(fos, cipher); int b; byte[] d = new byte[8]; while ((b = inputStream.read(d)) != -1) { cos.write(d, 0, b); } cos.flush(); cos.close(); inputStream.close(); File encryptedFile = new File(path.concat(".crypt")); return (encryptedFile.exists()); } and the decryption code is
public static void decrypt(String path, String password, String outPath) throws IOException, NoSuchAlgorithmException, NoSuchPaddingException, InvalidKeyException { FileInputStream fis = new FileInputStream(path); FileOutputStream fos = new FileOutputStream(outPath); byte[] key = (AppConstants.salt + password).getBytes("UTF-8"); MessageDigest sha = MessageDigest.getInstance("SHA-1"); key = sha.digest(key); key = Arrays.copyOf(key, 16); SecretKeySpec sks = new SecretKeySpec(key, "AES"); Cipher cipher = Cipher.getInstance("AES"); 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(); } If I decrypt the image, it will be shown and can be copied from the device. All I need is to load the encrypted image to an ImageView without saving the decrypted image to the device, so that no one can copy. Please someone help me.
1 Answers
Answers 1
An ImageView can show an in-memory android.graphics.Bitmap which can be read in directly from an InputStream.
For example, the decrypt() method could be adapted to return a Bitmap :
public Bitmap decrypt(String path, String password) throws IOException, NoSuchAlgorithmException, NoSuchPaddingException, InvalidKeyException { FileInputStream fis = new FileInputStream(path); byte[] key = (AppConstants.salt + password).getBytes("UTF-8"); MessageDigest sha = MessageDigest.getInstance("SHA-1"); key = sha.digest(key); key = Arrays.copyOf(key, 16); SecretKeySpec sks = new SecretKeySpec(key, "AES"); Cipher cipher = Cipher.getInstance("AES"); cipher.init(Cipher.DECRYPT_MODE, sks); CipherInputStream cis = new CipherInputStream(fis, cipher); Bitmap bitmap = BitmapFactory.decodeStream(cis); cis.close(); return bitmap; } (Although it's called Bitmap, it's fine to decode a .jpg or .png).
Then this can be shown in the ImageView:
ImageView imageView = findViewById(R.id.imageView); Bitmap bitmap = decrypt(path + ".crypt", password); imageView.setImageBitmap(bitmap); 
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