JAVA语言DES算法

1、DES算法：

 

 

	/**
	 * 加解密算法
	 * @param data  加解密数据
	 * @param key   秘钥
	 * @param mode  模式
	 * @return      加解密结果
	 */
	public static byte[] desCryt(byte[] data, byte[] key, int mode){
		byte[] result = null ;
		try {
			SecureRandom sr = new SecureRandom();  
			SecretKeyFactory keyFactory;
			DESKeySpec dks = new DESKeySpec(key);
			keyFactory = SecretKeyFactory.getInstance("DES");
			SecretKey secretkey = keyFactory.generateSecret(dks); 
			//创建Cipher对象
			Cipher cipher = Cipher.getInstance("DES/ECB/NoPadding");  
			//初始化Cipher对象  
			cipher.init(mode, secretkey, sr);  
			//加解密
			result = cipher.doFinal(data); 
		} catch (NoSuchAlgorithmException e) {
			e.printStackTrace();
		} catch (InvalidKeySpecException e) {
			e.printStackTrace();
		} catch (NoSuchPaddingException e) {
			e.printStackTrace();
		} catch (InvalidKeyException e) {
			e.printStackTrace();
		} catch (IllegalBlockSizeException e) {
			e.printStackTrace();
		} catch (BadPaddingException e) {
			e.printStackTrace();
		} 
		
		return result;
	}

 

 2、byte数组转换成16进制字符串

 

 

 

	 /**
	  * byte数组转换成16进制字符串
	 * @param b
	 * @return
	 */
	public static String bytes2HexString(byte[] b) {
		    String ret = "";
		    for (int i = 0; i < b.length; i++) {
		      String hex = Integer.toHexString(b[i] & 0xFF);
		      if (hex.length() == 1) {
		        hex = '0' + hex;
		      }
		      ret += hex.toUpperCase();
		    }
		    return ret;
	}

 

 

3、16进制字符串转成byte数组

 

 

	 /**
	  * 16进制字符串转成byte数组
	 * @param src
	 * @return
	 */
	public static byte[] hexString2Bytes(String src){
		    byte[] ret = new byte[8];
		    byte[] tmp = src.getBytes();
		    for(int i=0; i<8; i++){
		      ret[i] = uniteBytes(tmp[i*2], tmp[i*2+1]);
		    }
		    return ret;
	 }

 

 

 

	 public static byte uniteBytes(byte src0, byte src1) {
		    byte _b0 = Byte.decode("0x" + new String(new byte[]{src0})).byteValue();
		    _b0 = (byte)(_b0 << 4);
		    byte _b1 = Byte.decode("0x" + new String(new byte[]{src1})).byteValue();
		    byte ret = (byte)(_b0 ^ _b1);
		    return ret;
	}

 

 

 

执行

 

 

	public static void main(String[] args) {
		//加解密模式
		int mode = Cipher.ENCRYPT_MODE;
		//被加解密byte数组16进制字符串
		String dataHexString = "1234567887654321";
		//秘钥byte数组16进制字符串
		String keyHexString = "9AAB1D2EE004AAC3";
		byte[] data = hexString2Bytes(dataHexString);
		byte[] key = hexString2Bytes(keyHexString);
		byte[] result = desCryt(data, key, mode);
		//打印结果
		System.out.println("结果："+bytes2HexString(result));
	}

 

 结果：7D592BF239849E76

 

执行

 

 

	public static void main(String[] args) {
		//加解密模式
		int mode = Cipher.DECRYPT_MODE;
		//被加解密byte数组16进制字符串
		String dataHexString = "7D592BF239849E76";
		//秘钥byte数组16进制字符串
		String keyHexString = "9AAB1D2EE004AAC3";
		byte[] data = hexString2Bytes(dataHexString);
		byte[] key = hexString2Bytes(keyHexString);
		byte[] result = desCryt(data, key, mode);
		//打印结果
		System.out.println("结果："+bytes2HexString(result));
	}

 

 结果：1234567887654321

 

 

PS：

获取Cipher对象的时候一定要写成

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

不要写成

Cipher cipher = Cipher.getInstance("DES");

否则解密的时候会报错：

Given final block not properly padded

原因是Cipher cipher = Cipher.getInstance("DES");与Cipher cipher = Cipher.getInstance("DES/ECB/PKCS5Padding");等同，填充方式错误，加密的时候会得到16长度的字节数组。

 

JCE详解传送门：http://docs.oracle.com/javase/1.5.0/docs/guide/security/jce/JCERefGuide.html

 

附件是DES算法原理说明