android - 如何在不保存到设备的情况下在 ImageView 中加载 Cipher 加密的图像文件

Question

我正在创建一个具有内容安全性的应用程序，因为任何人都无法复制内容和文件。我正在使用密码直接从 URL 加密图像，而无需下载到设备。请在下面找到我的代码。

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();

而密码加密方法代码为

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());
}

解密密码是

 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();
}

如果我解密图像，它将显示并可以从设备复制。我只需要将加密图像加载到 ImageView，而不将解密图像保存到设备，这样就没有人可以复制了。请有人帮助我。

Answer 1

ImageView 可以显示内存中的 android.graphics.Bitmap，它可以直接从 InputStream 中读取。

例如，decrypt() 方法可以修改为返回一个 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;
}

(虽然叫Bitmap，但是解码成.jpg或者.png就可以了)

然后可以在 ImageView 中显示:

ImageView imageView = findViewById(R.id.imageView);
Bitmap bitmap = decrypt(path + ".crypt", password);
imageView.setImageBitmap(bitmap);