Question

我最近致力于文件加密/解密。

BadPaddingException：EVP_CipherFinal_ex：当我尝试使用相同的密钥解密文件时，总会发生这种情况。

代码段将发布在下方。

我做错了吗？

谢谢你的帮助。

加密

public static void encryptFile() {
    File file = new File(Environment.getExternalStorageDirectory().getPath() + "/" + TARGET_FILE);

    FileInputStream fileInputStream;
    FileOutputStream fileOutputStream;

    byte[] buffer = new byte[1024 * 8];

    IvParameterSpec ivParameterSpec = new IvParameterSpec("1234567890123456".getBytes());

    byte[] key = "only for testing".getBytes();
    MessageDigest sha;
    try {
        sha = MessageDigest.getInstance("SHA-1");
        key = sha.digest(key);
    } catch (NoSuchAlgorithmException e) {
        e.printStackTrace();
    }
    key = Arrays.copyOf(key, 16); // use only first 128 bit

    SecretKeySpec secretKeySpec = new SecretKeySpec(key, "AES");

    try {
        fileInputStream = new FileInputStream(file);
        fileOutputStream = new FileOutputStream(Environment.getExternalStorageDirectory().getPath() + "/" + ENCRYPT_FILE);

        Cipher cipher = Cipher.getInstance("AES/CBC/PKCS5Padding");
        cipher.init(Cipher.ENCRYPT_MODE, secretKeySpec, ivParameterSpec);

        //CipherOutputStream cipherOutputStream = new CipherOutputStream(fileOutputStream, cipher);

        int read;

        while ((read = fileInputStream.read(buffer)) > 0) {
            Log.i(TAG, "encrypt read= " + read);

            byte[] encryptedData = cipher.doFinal(buffer);
            if (encryptedData != null) {
                Log.i(TAG, "encrypted size= " + encryptedData.length);
                fileOutputStream.write(encryptedData, 0, read);
            }

            //cipherOutputStream.write(buffer, 0, buffer.length);
        }
        //cipherOutputStream.flush();
        //cipherOutputStream.close();
        fileInputStream.close();
        fileOutputStream.close();

    } catch (IOException | NoSuchAlgorithmException | NoSuchPaddingException
            | IllegalBlockSizeException | BadPaddingException
            | InvalidAlgorithmParameterException | InvalidKeyException e) {
        e.printStackTrace();
    }
}

解密

public static void decryptFile() {
    File file = new File(Environment.getExternalStorageDirectory().getPath() + "/" + ENCRYPT_FILE);

    FileInputStream fileInputStream;
    FileOutputStream fileOutputStream;

    byte[] buffer = new byte[1024 * 8];

    IvParameterSpec ivParameterSpec = new IvParameterSpec("1234567890123456".getBytes());

    byte[] key = "only for testing".getBytes();
    MessageDigest sha;
    try {
        sha = MessageDigest.getInstance("SHA-1");
        key = sha.digest(key);
    } catch (NoSuchAlgorithmException e) {
        e.printStackTrace();
    }
    key = Arrays.copyOf(key, 16); // use only first 128 bit

    SecretKeySpec secretKeySpec = new SecretKeySpec(key, "AES");

    try {
        fileInputStream = new FileInputStream(file);
        fileOutputStream = new FileOutputStream(Environment.getExternalStorageDirectory().getPath() + "/" + DECRYPT_FILE);

        Cipher cipher = Cipher.getInstance("AES/CBC/PKCS5Padding");
        cipher.init(Cipher.DECRYPT_MODE, secretKeySpec, ivParameterSpec);

        //CipherInputStream cipherInputStream = new CipherInputStream(fileInputStream, cipher);

        int read;

        while ((read = fileInputStream.read(buffer)) > 0) {
            Log.i(TAG, "decrypt read= " + read);

            byte[] decryptedData = cipher.doFinal(buffer);
            if (decryptedData != null) {
                Log.i(TAG, "decrypted size= " + decryptedData.length);
                fileOutputStream.write(decryptedData, 0, read);
            }

            //fileOutputStream.write(buffer, 0, buffer.length);
        }
        fileOutputStream.flush();
        fileOutputStream.close();
        //cipherInputStream.close();
        fileInputStream.close();

    } catch (IOException | NoSuchAlgorithmException | NoSuchPaddingException
            | IllegalBlockSizeException | BadPaddingException
            | InvalidAlgorithmParameterException | InvalidKeyException e) {
        e.printStackTrace();
    }
}

btw：当我使用CipherInputStream / CipherOutStream时它会正常工作。我想知道是否可以只使用FileInputStream / FileOutputStream？谢谢。

编辑：加密功能会将字节数组扩大到大约16个字节，我尝试增加解密的缓冲区大小，但仍然无法正常工作。

byte[] buffer = new byte[1024 * 8 + 16];

日志：

I /＃_：decrypt read = 8208

javax.crypto.BadPaddingException：EVP_CipherFinal_ex

at com.android.org.conscrypt.NativeCrypto.EVP_CipherFinal_ex（原生方法）

at com.android.org.conscrypt.OpenSSLCipher.doFinalInternal（OpenSSLCipher.java:430）

at com.android.org.conscrypt.OpenSSLCipher.engineDoFinal（OpenSSLCipher.java:466）

在javax.crypto.Cipher.doFinal（Cipher.java:1340）

在CryptoHelper.decryptFile（CryptoHelper.java:128）

已编辑此处根据#Robert的答案更新代码，以解决遇到与我相同问题的任何人。

加密：

int read;

        while ((read = fileInputStream.read(buffer)) > 0) {
            Log.i(TAG, "encrypt read= " + read);
            byte[] encryptedData = cipher.update(buffer, 0, read);
            //byte[] encryptedData = cipher.doFinal(buffer);
            if (encryptedData != null) {
                Log.i(TAG, "encrypted size= " + encryptedData.length);
                fileOutputStream.write(encryptedData, 0, encryptedData.length);
            }

            //cipherOutputStream.write(buffer, 0, buffer.length);
        }
        byte[] finals = cipher.doFinal();
        Log.i(TAG, "encrypted finals = " + finals.length);
        fileOutputStream.write(finals, 0, finals.length);

解密：

int read;

        while ((read = fileInputStream.read(buffer)) > 0) {
            Log.i(TAG, "decrypt read= " + read);

            //byte[] decryptedData = cipher.doFinal(buffer);
            byte[] decryptedData = cipher.update(buffer, 0, read);
            if (decryptedData != null) {
                Log.i(TAG, "decrypted size= " + decryptedData.length);
                fileOutputStream.write(decryptedData, 0, decryptedData.length);
            }

            //fileOutputStream.write(buffer, 0, buffer.length);
        }
        byte[] finals = cipher.doFinal();
        Log.i(TAG, "decrypted finals = " + finals.length);
        fileOutputStream.write(finals, 0, finals.length);

再次感谢罗伯特的帮助。

Answer 1

你的问题是你总是为每个数据块调用cipher.doFinal()，因为每个数据块都会被填充。

如果您使用cipher.update(...)进行/解密数据，并且在处理完最后一个块之后，只需拨打cipher.doFinal()一次。

更简单的方法是使用CipherInputStream / CipherOutputStream - 它完全按照我的描述（关闭流时调用doFinal）。

android AES解密文件：BadPaddingException：EVP_CipherFinal_ex

1 个答案: