DES 加密

来源：互联网发布：会java学php要多久编辑：程序博客网时间：2024/06/18 16:38

原文地址： http://blog.csdn.net/maxuyang1987/article/details/10226601

/**
   * DES加密
   * @param plainData
   * @param secretKey
   * @return
   * @throws Exception
   */
   public static String encryption(String plainData) throws Exception{

       Cipher cipher = null;
       try {
           cipher = Cipher.getInstance(DES_ALGORITHM);
           cipher.init(Cipher.ENCRYPT_MODE, generateKey(KEY));

       } catch (NoSuchAlgorithmException e) {
           e.printStackTrace();
       } catch (NoSuchPaddingException e) {
           e.printStackTrace();
       }catch(InvalidKeyException e){

       }

       try {
           // 为了防止解密时报javax.crypto.IllegalBlockSizeException: Input length must be multiple of 8 when decrypting with padded cipher异常，
           // 不能把加密后的字节数组直接转换成字符串
           byte[] buf = cipher.doFinal(plainData.getBytes());

           return Base64Utils.encode(buf);

       } catch (IllegalBlockSizeException e) {
           e.printStackTrace();
           throw new Exception("IllegalBlockSizeException", e);
       } catch (BadPaddingException e) {
           e.printStackTrace();
           throw new Exception("BadPaddingException", e);
       }

   }

   /**
   * DES解密
   * @param secretData
   * @param secretKey
   * @return
   * @throws Exception
   */
   public static String decryption(String secretData) throws Exception{

       Cipher cipher = null;
       try {
           cipher = Cipher.getInstance(DES_ALGORITHM);
           cipher.init(Cipher.DECRYPT_MODE, generateKey(KEY));

       } catch (NoSuchAlgorithmException e) {
           e.printStackTrace();
           throw new Exception("NoSuchAlgorithmException", e);
       } catch (NoSuchPaddingException e) {
           e.printStackTrace();
           throw new Exception("NoSuchPaddingException", e);
       }catch(InvalidKeyException e){
           e.printStackTrace();
           throw new Exception("InvalidKeyException", e);

       }

       try {

           byte[] buf = cipher.doFinal(Base64Utils.decode(secretData.toCharArray()));

           return new String(buf);

       } catch (IllegalBlockSizeException e) {
           e.printStackTrace();
           throw new Exception("IllegalBlockSizeException", e);
       } catch (BadPaddingException e) {
           e.printStackTrace();
           throw new Exception("BadPaddingException", e);
       }
   }


   /**
   * 获得秘密密钥
   *
   * @param secretKey
   * @return
   * @throws NoSuchAlgorithmException
   */
   private static SecretKey generateKey(String secretKey) throws NoSuchAlgorithmException{
       //SecureRandom secureRandom = new SecureRandom(secretKey.getBytes());
          SecureRandom secureRandom = SecureRandom.getInstance("SHA1PRNG");
          secureRandom.setSeed(secretKey.getBytes());
       // 为我们选择的DES算法生成一个KeyGenerator对象
       KeyGenerator kg = null;
       try {
           kg = KeyGenerator.getInstance(DES_ALGORITHM);
       } catch (NoSuchAlgorithmException e) {
       }
       kg.init(secureRandom);
       //kg.init(56, secureRandom);

       // 生成密钥
       return kg.generateKey();
   }



   static class Base64Utils {

       static private char[] alphabet = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/=".toCharArray();
       static private byte[] codes = new byte[256];
       static {
           for (int i = 0; i < 256; i++)
               codes[i] = -1;
           for (int i = 'A'; i <= 'Z'; i++)
               codes[i] = (byte) (i - 'A');
           for (int i = 'a'; i <= 'z'; i++)
               codes[i] = (byte) (26 + i - 'a');
           for (int i = '0'; i <= '9'; i++)
               codes[i] = (byte) (52 + i - '0');
           codes['+'] = 62;
           codes['/'] = 63;
       }

       /**
       * 将原始数据编码为base64编码
       */
       static public String encode(byte[] data) {
           char[] out = new char[((data.length + 2) / 3) * 4];
           for (int i = 0, index = 0; i < data.length; i += 3, index += 4) {
               boolean quad = false;
               boolean trip = false;
               int val = (0xFF & (int) data[i]);
               val <<= 8;
               if ((i + 1) < data.length) {
                   val |= (0xFF & (int) data[i + 1]);
                   trip = true;
               }
               val <<= 8;
               if ((i + 2) < data.length) {
                   val |= (0xFF & (int) data[i + 2]);
                   quad = true;
               }
               out[index + 3] = alphabet[(quad ? (val & 0x3F) : 64)];
               val >>= 6;
               out[index + 2] = alphabet[(trip ? (val & 0x3F) : 64)];
               val >>= 6;
               out[index + 1] = alphabet[val & 0x3F];
               val >>= 6;
               out[index + 0] = alphabet[val & 0x3F];
           }

           return new String(out);
       }

       /**
       * 将base64编码的数据解码成原始数据
       */
       static public byte[] decode(char[] data) {
           int len = ((data.length + 3) / 4) * 3;
           if (data.length > 0 && data[data.length - 1] == '=')
               --len;
           if (data.length > 1 && data[data.length - 2] == '=')
               --len;
           byte[] out = new byte[len];
           int shift = 0;
           int accum = 0;
           int index = 0;
           for (int ix = 0; ix < data.length; ix++) {
               int value = codes[data[ix] & 0xFF];
               if (value >= 0) {
                   accum <<= 6;
                   shift += 6;
                   accum |= value;
                   if (shift >= 8) {
                       shift -= 8;
                       out[index++] = (byte) ((accum >> shift) & 0xff);
                   }
               }
           }
           if (index != out.length)
               throw new Error("miscalculated data length!");
           return out;
       }
   }


   public static void main(String[] a) throws Exception{
       String input = "test";

       String result = encryption(input);
       System.out.println(result);

       System.out.println( decryption(result));
           //H+Ac2AysRv6CWn3ncH1HIw==
   }
}

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