信息安全_分组加密算法_DES算法_加…

【题意要求】利用Java中的分组加密的相关的类包完成对输入字符串的操作。

    (1)利用java中的KeyGenerator类创建对称秘钥，利用工厂类KeyGenerator的静态方法getInstance()获得KeyGenerator()类对象；

    (2)方法getInstance()的参数为字符串类型，指定加密算法的名称如：Blowfish、DES、DESede、HmacMD5或HmacSHA1等，本题使用DES这个参数；

    (3)利用工厂类Cipher的对象可以创建密码器。同样的，getInstance()的参数为字符串类型，指定加密算法的名称，本题指定为“DES”。

   其中public static  byte[]getEncCode(byte[] byteS, Keykey)方法，用来处理给出的字节数组在利用key密钥参数的基础上进行加密；而publicstatic  byte[]getDesCode(byte[] byteD , Keykey)方法，用来处理已经加密的字符串，利用同样的密钥进行解密。

package Practice2;

import java.io.UnsupportedEncodingException;
import java.security.Key;
import java.security.NoSuchAlgorithmException;
import java.util.Scanner;

import javax.crypto.Cipher;
import javax.crypto.KeyGenerator;
import javax.crypto.SecretKey;

public class DESForString {
 public static void main(String[] args) throwsNoSuchAlgorithmException, UnsupportedEncodingException{
  selectProcess();
 }
 
 public static voidselectProcess()  throws NoSuchAlgorithmException,UnsupportedEncodingException{
  KeyGenerator kg =KeyGenerator.getInstance("DES");
  kg.init(56);//DES needs 56bytes.
  // 生成秘密密钥
  final SecretKey secretKey =kg.generateKey();
//  byte[] key =secretKey.getEncoded();
  System.out.println("What youare operating is the algorithm named DES to encrypt thestring.");
  System.out.println(secretKey);
  Scanner scanin = newScanner(System.in);
  System.out.print("Please inputthe string that you want to encrypt:\t");
  String source =scanin.nextLine();
  byte[] encode =getEncCode(source.getBytes(), secretKey);
  System.out.println(encode);
  System.out.print("Get thestring that you have decrypt:\t");
  byte[] decode =getDesCode(encode, secretKey);
  System.out.println(newString(decode, "gb2312"));//可处理汉字的加解密
 }
 
 public static  byte[]getEncCode(byte[] byteS, Key key) {
  byte[] byteFina = null;
  Cipher cipher;
  try {
   cipher =Cipher.getInstance("DES");
   cipher.init(Cipher.ENCRYPT_MODE,key);
   byteFina =cipher.doFinal(byteS);
  } catch (Exception e) {
   e.printStackTrace();
  } finally {
   cipher =null;
  }
  return byteFina;
 }
 
 public static  byte[]getDesCode(byte[] byteD , Key key) {
  Cipher cipher;
  byte[] byteFina = null;
  try {
   cipher =Cipher.getInstance("DES");
   cipher.init(Cipher.DECRYPT_MODE,key);
   byteFina =cipher.doFinal(byteD);
  } catch (Exception e) {
   e.printStackTrace();
  } finally {
   cipher =null;
  }
  return byteFina;

 }
}