DES算法

 

 

   public String getRandomString(final int size) {
        char hexDigits[] = { '0', '1', '2', '3', '4', '5', '6', '7', '8', '9', 'a', 'b', 'c', 'd',
                'e', 'f' };

        Random random = new Random();
        StringBuffer randomBuffer = new StringBuffer();
        int index = 0;
        int valueIndex;
        while (index < size) {
            valueIndex = random.nextInt(16);
            randomBuffer.append(hexDigits[valueIndex]);
            index++;
        }

        // System.out.println(randomBuffer.toString());
        return randomBuffer.toString();
    }

    public void doDESTest() {
        String content = getRandomString(1 << 10);
        String password = getRandomString(16);
        System.out.println(content);
        byte encrypt[] = desEncrypt(content.getBytes(), password);
        if (encrypt != null) {
            System.out.println(new String(encrypt));
            byte src[] = desDecrypt(encrypt, password);
            System.out.println(new String(src));
        }
    }

    public byte[] desEncrypt(byte[] datasource, String password) {
        try {
            SecureRandom random = new SecureRandom();
            DESKeySpec desKey = new DESKeySpec(password.getBytes());
            // 创建一个密匙工厂，然后用它把DESKeySpec转换成
            SecretKeyFactory keyFactory = SecretKeyFactory.getInstance("DES");
            SecretKey securekey = keyFactory.generateSecret(desKey);
            // Cipher对象实际完成加密操作
            Cipher cipher = Cipher.getInstance("DES");
            // 用密匙初始化Cipher对象
            cipher.init(Cipher.ENCRYPT_MODE, securekey, random);
            // 现在，获取数据并加密
            // 正式执行加密操作
            return cipher.doFinal(datasource);
        } catch (Throwable e) {
            e.printStackTrace();
            return null;
        }
    }

    private byte[] desDecrypt(byte[] src, String password) {
        // DES算法要求有一个可信任的随机数源
        SecureRandom random = new SecureRandom();
        try {
            // 创建一个DESKeySpec对象
            DESKeySpec desKey = new DESKeySpec(password.getBytes());
            // 创建一个密匙工厂
            SecretKeyFactory keyFactory = SecretKeyFactory.getInstance("DES");
            // 将DESKeySpec对象转换成SecretKey对象
            SecretKey securekey = keyFactory.generateSecret(desKey);
            // Cipher对象实际完成解密操作
            Cipher cipher = Cipher.getInstance("DES");
            // 用密匙初始化Cipher对象
            cipher.init(Cipher.DECRYPT_MODE, securekey, random);
            // 真正开始解密操作
            return cipher.doFinal(src);
        } catch (Exception e) {
            e.printStackTrace();
            return null;
        }
    }