AES/CBC/PKCS5padding错误的解密：给定的最终块没有正确填充

Question

加密：

void encrypt() throws Exception{
    char[] password = passwordText.getText().toCharArray();
    byte[] salt = new byte[8];

    /* Creating and saving salt */
    salt = saveSalt(salt);

    /* Securing password */
    SecretKeyFactory factory = SecretKeyFactory.getInstance("PBKDF2WithHmacSHA256");
    KeySpec spec = new PBEKeySpec(password, salt, 65536, 128);
    SecretKey tmp = factory.generateSecret(spec);
    SecretKey secret = new SecretKeySpec(tmp.getEncoded(), "AES");

    if (choosedFile != null) {
        /* Choosing algorithm for decryption */
        Cipher cipher = Cipher.getInstance("AES/CBC/PKCS5Padding");

        /* Getting plain file */
        CipherInputStream fis = new CipherInputStream(new  FileInputStream(choosedFile), cipher);
        CipherOutputStream fos = new CipherOutputStream(new FileOutputStream(choosedFile+".encrypted"), cipher);

        /* Encrypting and Measuring */
        long startTime = System.currentTimeMillis();
        cipher.init(Cipher.ENCRYPT_MODE, secret);
        byte[] rawText = new byte[128];
        int count;
        while((count = fis.read(rawText)) > 0) {
            System.out.println(count);
            byte[] encryptedText = cipher.doFinal(rawText);
            fos.write(encryptedText, 0, count);
        }
        long stopTime = System.currentTimeMillis();

        fis.close();
        fos.close();

        /* Creating initialization vector and storing*/
        byte[] iVector = cipher.getIV();
        saveIVector(iVector);

        text.setText(text.getText() + "File was encrypted in " + (stopTime - startTime) + "ms.\n");
    }

}

解密：

    void decrypt() throws Exception {
    /* Getting salt */
    byte[] salt = getSalt();
    /* Getting initialization vector */
    byte[] iVector = getIVector();
    /* Getting user password */
    char[] password = passwordText.getText().toCharArray();


    /* Securing password */
    SecretKeyFactory factory = SecretKeyFactory.getInstance("PBKDF2WithHmacSHA256");
    KeySpec spec = new PBEKeySpec(password, salt, 65536, 128);
    SecretKey tmp = factory.generateSecret(spec);
    SecretKey secret = new SecretKeySpec(tmp.getEncoded(), "AES");

    if (choosedFile != null) {

        /* Choosing algorithm for decryption */
        Cipher cipher = Cipher.getInstance("AES/CBC/PKCS5Padding");
        /* Getting ciphered file */


        CipherInputStream fis = new CipherInputStream(new  FileInputStream(choosedFile), cipher);
        CipherOutputStream fos = new CipherOutputStream(new FileOutputStream(choosedFile+".decrypted"), cipher);

        /* Decrypting and Measuring */
        long startTime = System.currentTimeMillis();
        cipher.init(Cipher.DECRYPT_MODE, secret, new IvParameterSpec(iVector));
        byte[] rawText = new byte[128];
        int count;
        while((count = fis.read(rawText)) > 0) {
                byte[] encryptedText = cipher.doFinal(rawText);
                fos.write(encryptedText, 0, count);
            }

        long stopTime = System.currentTimeMillis();

        fis.close();
        fos.close();

Answer 1

担心“直到我不得不把大文件切成固定大小的块”。

使用“chunk”代替上面的“block”，因为“block”在像AES这样的分组密码中有特定的含义。

玩具用这些块做什么，把它们连接起来？

在CBC模式下，在第一个块之后，上一个加密的块值被有效地用作下一个块的IV。因此，在拆分和连接块时，前一个块的最后一个块的值是下一个块的IV。

参见CBC模式。

还是你在做完全不同的事情？