JAVA语言DES算法------

1、DES算法：

Java代码 收藏代码
/**

• 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

Java代码 收藏代码
/**

• byte数组转换成16进制字符串
  • @param b
  • @return
    */
    ublic 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

Java代码 收藏代码
/**

• 16进制字符串转成byte数组
  • @param src
  • @return
    /
    ublic 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[i2], tmp[i*2+1]);
    }
    return ret;
    }

Java代码 收藏代码
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

Java代码 收藏代码
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

Java代码 收藏代码
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