给定最终块未正确填充

Question

我正在尝试实现基于密码的加密算法，但出现此异常：

javax.crypto.BadPaddingException：给定最终块，未正确填充

可能是什么问题？（我是Java新手。）

这是我的代码：

public class PasswordCrypter {

    private Key key;

    public PasswordCrypter(String password)  {

        try{

            KeyGenerator generator;

            generator = KeyGenerator.getInstance("DES");

            SecureRandom sec = new SecureRandom(password.getBytes());

            generator.init(sec);

            key = generator.generateKey();

        } catch (Exception e) {

            e.printStackTrace();

        }

    }

    public byte[] encrypt(byte[] array) throws CrypterException {

        try{

            Cipher cipher = Cipher.getInstance("DES/ECB/PKCS5Padding");

            cipher.init(Cipher.ENCRYPT_MODE, key);

            return cipher.doFinal(array);

        } catch (Exception e) { 

            e.printStackTrace();

        }

        return null;

    }

    public byte[] decrypt(byte[] array) throws CrypterException{

        try{

            Cipher cipher = Cipher.getInstance("DES/ECB/PKCS5Padding");

            cipher.init(Cipher.DECRYPT_MODE, key);

            return cipher.doFinal(array);

        } catch(Exception e ){

            e.printStackTrace();

        }

        return null;

    }

}

（JUnit测试）

public class PasswordCrypterTest {

    private static final byte[] MESSAGE = "Alpacas are awesome!".getBytes();

    private PasswordCrypter[] passwordCrypters;

    private byte[][] encryptedMessages;

    @Before

    public void setUp() {

        passwordCrypters = new PasswordCrypter[] {

            new PasswordCrypter("passwd"),

            new PasswordCrypter("passwd"),

            new PasswordCrypter("otherPasswd")

        };

        encryptedMessages = new byte[passwordCrypters.length][];

        for (int i = 0; i < passwordCrypters.length; i++) {

            encryptedMessages[i] = passwordCrypters[i].encrypt(MESSAGE);

        }

    }