DES对称加密算法

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前言：

1.DES是一个经典的分组加密算法，以64位为分组对数据进行加密（分组），加密和解密使用的是同一个算法（对称）；
2.**长64位，事实上56位参与DES运算，每8位中最后一位是奇偶校验位（保证**每8位都有奇数个1）；
3.加密过程：对于每一个明文分组，进行一次初始置换IP（Initial Permutation），之后循环使用16个子**进行16轮加密，最后进行一次末置换(IP^-1)。
 

public class  DesEncrypt {
	private static Logger logger = Logger.getLogger(DesEncrypt.class);
	
    //算法名称 
    public static final String KEY_ALGORITHM = "DES";
    public static final String KEY_KEY = "A1B2C3D4E5F60708";
    //算法名称/加密模式/填充方式 
    //DES共有四种工作模式-->>ECB：电子密码本模式、CBC：加密分组链接模式、CFB：加密反馈模式、OFB：输出反馈模式
    //public static final String CIPHER_ALGORITHM = "DES/ECB/NoPadding";
   public static final String CIPHER_ALGORITHM = "DES/ECB/PKCS5Padding";
    /**
     *   
     * 生成**key对象
     * @param KeyStr **字符串 
     * @return **对象 
     * @throws InvalidKeyException   
     * @throws NoSuchAlgorithmException   
     * @throws InvalidKeySpecException   
     * @throws Exception 
     */
    private static SecretKey keyGenerator(String keyStr) throws Exception {
        byte input[] = HexString2Bytes(keyStr);
        DESKeySpec desKey = new DESKeySpec(input);
        //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);
        return securekey;
    }

    private static int parse(char c) {
        if (c >= 'a') return (c - 'a' + 10) & 0x0f;
        if (c >= 'A') return (c - 'A' + 10) & 0x0f;
        return (c - '0') & 0x0f;
    }

    // 从十六进制字符串到字节数组转换 
    public static byte[] HexString2Bytes(String hexstr) {
        byte[] b = new byte[hexstr.length() / 2];
        int j = 0;
        for (int i = 0; i < b.length; i++) {
            char c0 = hexstr.charAt(j++);
            char c1 = hexstr.charAt(j++);
            b[i] = (byte) ((parse(c0) << 4) | parse(c1));
        }
        return b;
    }

    /** 
     * 加密数据
     * @param data 待加密数据
     * @param key **
     * @return 加密后的数据 
     */
    public static String encrypt(String data, String key)  {
        byte[] results = null;
		try {
			Key deskey = keyGenerator(key);
			// 实例化Cipher对象，它用于完成实际的加密操作
			Cipher cipher = Cipher.getInstance(CIPHER_ALGORITHM);
			SecureRandom random = new SecureRandom();
			// 初始化Cipher对象，设置为加密模式
			cipher.init(Cipher.ENCRYPT_MODE, deskey, random);
			results = cipher.doFinal(data.getBytes());
			// 该部分是为了与加解密在线测试网站的十六进制结果进行核对
			for (int i = 0; i < results.length; i++) {
			    System.out.print(results[i] + " ");
			}
			System.out.println();
			// 执行加密操作。加密后的结果通常都会用Base64编码进行传输 
		} catch (InvalidKeyException e) {
			e.printStackTrace();
		} catch (NoSuchAlgorithmException e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		} catch (NoSuchPaddingException e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		} catch (IllegalBlockSizeException e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		} catch (BadPaddingException e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		} catch (Exception e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		}
        return Base64.encodeBase64String(results);
    }

    /** 
     * 解密数据 
     * @param data 待解密数据 
     * @param key ** 
     * @return 解密后的数据 
     */
    public static String decrypt(String data, String key)  {
    	byte[]  ret  = null;
    	try {
			Key deskey = keyGenerator(key);
			Cipher cipher = Cipher.getInstance(CIPHER_ALGORITHM);
			//初始化Cipher对象，设置为解密模式
			cipher.init(Cipher.DECRYPT_MODE, deskey);
			// 执行解密操作
			ret	= cipher.doFinal(Base64.decodeBase64(data));
		} catch (InvalidKeyException e) {
			e.printStackTrace();
		} catch (NoSuchAlgorithmException e) {
			e.printStackTrace();
		} catch (NoSuchPaddingException e) {
			e.printStackTrace();
		} catch (IllegalBlockSizeException e) {
			e.printStackTrace();
		} catch (BadPaddingException e) {
			e.printStackTrace();
		} catch (Exception e) {
			e.printStackTrace();
		}
		return new String(ret);
    }

  
    
	/**
	 * 批量验证权限
	 * @param request
	 * @param chkParamNames
	 * @return
	 */
	public static boolean checkScrect(HttpServletRequest request,
			String[] chkParamNames) {
		StringBuffer buffer = new StringBuffer();
		for(int i=0;i<chkParamNames.length;i++){
			String param=StringUtils.trimToEmpty(request.getParameter(chkParamNames[i]));
			buffer.append(new String(DesEncrypt.decrypt(param, DesEncrypt.KEY_KEY)));
		}
		String secret=request.getParameter(AppConstant.PARAM_SECRECT);
		String secretD=new String(DesEncrypt.decrypt(secret,DesEncrypt.KEY_KEY ));
	    logger.info("buffer:"+buffer.toString());
		logger.info("secretD:"+secretD);
		if(buffer.toString().equals(secretD)){
			return true;
		}
		return false;
	}
    
	  public static void main(String[] args) throws Exception {
        String source = "哈哈";
        System.out.println("原文: " + source);
        String key = "A1B2C3D4E5F60708";
        String encryptData = encrypt(source, key);
        System.out.println("加密后: " + encryptData);
        String decryptData = decrypt(encryptData, key);
        System.out.println("解密后: " + decryptData);
        
        System.out.println(DesEncrypt.decrypt("Xo5QuTUR/GIMocTHz1FIQIc9+Id22JDj", DesEncrypt.KEY_KEY));
    }
    
}

 

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