使用 AES 算法解密时获得 BadPaddingException

Question

使用 AES 算法解密时出现以下错误。我不明白我哪里出错了。几天前，这段代码对我来说工作正常，但它没有抛出这样的错误。

我得到的错误：-

java.io.IOException: javax.crypto.BadPaddingException: Given final block not properly padded
at javax.crypto.CipherInputStream.getMoreData(CipherInputStream.java:121)
at javax.crypto.CipherInputStream.read(CipherInputStream.java:239)
at javax.crypto.CipherInputStream.read(CipherInputStream.java:215)
at userInterface.Decryption.decryption(Decryption.java:61)
at userInterface.DecodingTab$DecodeButtonActionListener.actionPerformed(DecodingTab.java:295)
at javax.swing.AbstractButton.fireActionPerformed(Unknown Source)
at javax.swing.AbstractButton$Handler.actionPerformed(Unknown Source)
at javax.swing.DefaultButtonModel.fireActionPerformed(Unknown Source)
at javax.swing.DefaultButtonModel.setPressed(Unknown Source)
at javax.swing.plaf.basic.BasicButtonListener.mouseReleased(Unknown Source)
at java.awt.Component.processMouseEvent(Unknown Source)
at javax.swing.JComponent.processMouseEvent(Unknown Source)
at java.awt.Component.processEvent(Unknown Source)
at java.awt.Container.processEvent(Unknown Source)
at java.awt.Component.dispatchEventImpl(Unknown Source)
at java.awt.Container.dispatchEventImpl(Unknown Source)
at java.awt.Component.dispatchEvent(Unknown Source)
at java.awt.LightweightDispatcher.retargetMouseEvent(Unknown Source)
at java.awt.LightweightDispatcher.processMouseEvent(Unknown Source)
at java.awt.LightweightDispatcher.dispatchEvent(Unknown Source)
at java.awt.Container.dispatchEventImpl(Unknown Source)
at java.awt.Window.dispatchEventImpl(Unknown Source)
at java.awt.Component.dispatchEvent(Unknown Source)
at java.awt.EventQueue.dispatchEventImpl(Unknown Source)
at java.awt.EventQueue.access$500(Unknown Source)
at java.awt.EventQueue$3.run(Unknown Source)
at java.awt.EventQueue$3.run(Unknown Source)
at java.security.AccessController.doPrivileged(Native Method)
at java.security.ProtectionDomain$JavaSecurityAccessImpl.doIntersectionPrivilege(Unknown Source)
at java.security.ProtectionDomain$JavaSecurityAccessImpl.doIntersectionPrivilege(Unknown Source)
at java.awt.EventQueue$4.run(Unknown Source)
at java.awt.EventQueue$4.run(Unknown Source)
at java.security.AccessController.doPrivileged(Native Method)
at  ... 40 more  

加密代码：-

public Encryption(String key2, FileInputStream fileInputStream,
        FileOutputStream fileOutputStream) {
    this.key = key2;
    this.is = fileInputStream;
    this.os = fileOutputStream;
}
public boolean encryption() throws Throwable {
    MessageDigest md5 = MessageDigest.getInstance("MD5");
      md5.update(key.getBytes());
      SecretKeySpec key = new SecretKeySpec(md5.digest(), "AES");
      cipher = Cipher.getInstance("AES");
      cipher.init(Cipher.ENCRYPT_MODE, key);
      cipherInputStream = new CipherInputStream(is, cipher);
    byte[] bytes = new byte[64];
    int numBytes;
    while ((numBytes = cipherInputStream.read(bytes)) != -1) {
        os.write(bytes, 0, numBytes);
    }
    os.flush();
    os.close();
    is.close();
    cipherInputStream.close();
    return true;
}

**解密代码：- **

public Decryption(String decodingKey, File fileOutput) {
    this.key = decodingKey;
    this.outputFile = fileOutput.getAbsolutePath();
}
public boolean decryption() throws IOException, Throwable {
    encryptedFile = new File("Crypto\EncryptedFile.txt");
    is = new FileInputStream(encryptedFile);
    File outputF = new File(outputFile);
    os = new FileOutputStream(outputF);
    MessageDigest md5 = MessageDigest.getInstance("MD5");
      md5.update(key.getBytes());
      SecretKeySpec key = new SecretKeySpec(md5.digest(), "AES");
      cipher = Cipher.getInstance("AES");
      //cipher = Cipher.getInstance("AES/CBC/NoPadding");
      cipher.init(Cipher.DECRYPT_MODE, key);
    cipherInputStream = new CipherInputStream(is, cipher);
    byte[] bytes = new byte[64];
    int numBytes;
    while ((numBytes = cipherInputStream.read(bytes)) != -1) {
        os.write(bytes, 0, numBytes);
    }
    os.flush();
    os.close();
    cipherInputStream.close();
    is.close();
    encryptedFile.delete();
    return true;
}  

请让我知道我哪里出错了。

Answer 1

您应该在加密部分使用 CipherOutputStream，并确保在其上调用 close，以便写入最终的填充数据。