Question

我有很少的AES加密视频，在玩ExoPlayer之前我需要解密。这些视频将包含在应用程序的资源文件夹中，而其中很少需要在SD卡上。

我一直在使用提供的实用程序类来解密视频，但它似乎无法正常工作。

static String key = "xxx"; // key should be exactly 16bit long
private static final String ALGORITHM = "AES";
private static final String TRANSFORMATION = "AES";

public static void encrypt(File inputFile, File outputFile) throws CryptoException {
    doCrypto(Cipher.ENCRYPT_MODE, inputFile, outputFile);
}
public static void decrypt(File inputFile, File outputFile) throws CryptoException {
    doCrypto(Cipher.DECRYPT_MODE, inputFile, outputFile);
}

private static void doCrypto(int cipherMode, File inputFile, File outputFile) throws CryptoException {
    try {
        Key secretKey = new SecretKeySpec(key.getBytes(), ALGORITHM);
        Cipher cipher = Cipher.getInstance(TRANSFORMATION);
        cipher.init(cipherMode, secretKey);

        FileInputStream inputStream = new FileInputStream(inputFile);
        byte[] inputBytes = new byte[(int) inputFile.length()];
        inputStream.read(inputBytes);

        byte[] outputBytes = cipher.doFinal(inputBytes);

        FileOutputStream outputStream = new FileOutputStream(outputFile);
        outputStream.write(outputBytes);

        inputStream.close();
        outputStream.close();
    } catch (IOException | NoSuchAlgorithmException | InvalidKeyException | NoSuchPaddingException | BadPaddingException | IllegalBlockSizeException e) {
        e.printStackTrace();
        throw new CryptoException("Error encrypting/decrypting file", e);
    }
}

对于assets文件夹中的视频，我尝试直接传递从getAssets().open(filePath)返回的InputStream，但是它提供了一些与填充相关的错误。所以我先使用以下代码将视频文件复制到内部存储

public static void copyFromAssets(Context context, String filePath, File outputFile) {
    InputStream in = null;
    OutputStream out = null;
    try {
        in = context.getAssets().open(filePath);
        out = new FileOutputStream(outputFile);
        copyFile(in, out);
    } catch (IOException e) {
        e.printStackTrace();
        LumberJack.e("tag", "Failed to copy asset file: " + filePath);
    } finally {
        if (in != null) {
            try {
                in.close();
            } catch (IOException e) {
            }
        }
        if (out != null) {
            try {
                out.close();
            } catch (IOException e) {
                // NOOP
            }
        }
    }
}

private static void copyFile(InputStream in, OutputStream out) throws IOException {
    byte[] buffer = new byte[1024];
    int read;
    while ((read = in.read(buffer)) != -1) {
        out.write(buffer, 0, read);
    }
}

视频在那里，但由于它是一个加密的视频我无法播放。当我试图解密提取的视频文件时，我得到以下异常 -

javax.crypto.IllegalBlockSizeException: last block incomplete in decryption
     at com.android.org.bouncycastle.jcajce.provider.symmetric.util.BaseBlockCipher.engineDoFinal(BaseBlockCipher.java:853)
     at javax.crypto.Cipher.doFinal(Cipher.java:1502)
     at com.example.utilities.CryptoUtils.doCrypto(CryptoUtils.java:42)
     at com.example.utilities.CryptoUtils.decrypt(CryptoUtils.java:29)
     at com.example.activities.HomeActivity.onVideoPlayButtonClick(HomeActivity.java:107)
     at java.lang.reflect.Method.invoke(Native Method)
     at org.greenrobot.eventbus.EventBus.invokeSubscriber(EventBus.java:485)
     at org.greenrobot.eventbus.EventBus.postToSubscription(EventBus.java:420)
     at org.greenrobot.eventbus.EventBus.postSingleEventForEventType(EventBus.java:397)
     at org.greenrobot.eventbus.EventBus.postSingleEvent(EventBus.java:370)
     at org.greenrobot.eventbus.EventBus.post(EventBus.java:251)
     at com.example.viewmodels.BaseDataLevelItemView$1.onClick(BaseDataLevelItemView.java:65)
     at android.view.View.performClick(View.java:5210)
     at android.view.View$PerformClick.run(View.java:21169)
     at android.os.Handler.handleCallback(Handler.java:739)
     at android.os.Handler.dispatchMessage(Handler.java:95)
     at android.os.Looper.loop(Looper.java:148)
     at android.app.ActivityThread.main(ActivityThread.java:5451)
     at java.lang.reflect.Method.invoke(Native Method)
     at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:726)
     at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:616)

我不确定我在这里做错了什么。相同的解密代码已在早期版本的应用程序中使用相同的视频，但现在提出问题。我已经检查了与相同异常相关的Stackoverflow上的其他一些答案，但是大多数答案都与密文中的编码问题有关。我这里没有字符串，但是文件。

如果您已经发现问题，我怎么能在这里找出错误，如何解决？

Answer 1

感谢Ebbe M. Pedersen的建议，我实际上尝试加密文件并尝试使用相同的代码进行解密。
因此，确认有一些其他算法或其他东西用于加密文件。幸运的是，我在旧的提交中找到了它。

解密文件时解密时的最后一个块不完整

1 个答案: