java 简单的des加密示例

1.加密结果

　　包含 ： 对int加密 、对string加密、对byte[]加密。

 10-09 18:33:32.484 7617-7617/com.example.tt.downtest D/CipherUtil: init Cipher needs 18 ms
 10-09 18:33:32.484 7617-7617/com.example.tt.downtest D/CipherUtil: -----=====-----------=========-----
 10-09 18:33:32.484 7617-7617/com.example.tt.downtest D/CipherUtil: bytes data is  [ ��
                                                                     ]
 10-09 18:33:32.490 7617-7617/com.example.tt.downtest D/CipherUtil: encrypt ret is [ ����h�1 !m�7M��J�˝��� ] needs 5 ms
 10-09 18:33:32.490 7617-7617/com.example.tt.downtest D/CipherUtil: decrypt ret is [ ��
                                                                     ] needs 0 ms
 10-09 18:33:32.490 7617-7617/com.example.tt.downtest D/CipherUtil: -----=====-----------=========-----
 10-09 18:33:32.490 7617-7617/com.example.tt.downtest D/CipherUtil: int data is  [ 100 ]
 10-09 18:33:32.490 7617-7617/com.example.tt.downtest D/CipherUtil: encrypt ret is [ [��sZ"� ] needs 0 ms
 10-09 18:33:32.490 7617-7617/com.example.tt.downtest D/CipherUtil: decrypt ret is [ 100 ] needs 0 ms
 10-09 18:33:32.490 7617-7617/com.example.tt.downtest D/CipherUtil: -----=====-----------=========-----
 10-09 18:33:32.491 7617-7617/com.example.tt.downtest D/CipherUtil: string data is [ hello world ]
 10-09 18:33:32.491 7617-7617/com.example.tt.downtest D/CipherUtil: encrypt ret is [ ��́��|��@�y��y ] needs 0 ms
 10-09 18:33:32.491 7617-7617/com.example.tt.downtest D/CipherUtil: decrypt ret is [ hello world ] needs 0 ms

2.完整示例

 package com.example.tt.downtest;

 import android.util.Log;

 import java.security.InvalidKeyException;
 import java.security.NoSuchAlgorithmException;
 import java.security.spec.InvalidKeySpecException;

 import javax.crypto.BadPaddingException;
 import javax.crypto.Cipher;
 import javax.crypto.IllegalBlockSizeException;
 import javax.crypto.NoSuchPaddingException;
 import javax.crypto.SecretKey;
 import javax.crypto.SecretKeyFactory;
 import javax.crypto.spec.DESKeySpec;

 public class CipherUtil {

     final String TAG = "CipherUtil";
     long begin,end;

     String algorithm = "DES";
     Cipher cipher;
     SecretKey secretKey;
     ,};

     void init(){
         begin = System.currentTimeMillis();
         try {
             cipher = Cipher.getInstance(algorithm);
             DESKeySpec keySpec = new DESKeySpec(key);
             SecretKeyFactory keyFactory = SecretKeyFactory.getInstance(algorithm);
             secretKey = keyFactory.generateSecret(keySpec);
         } catch (NoSuchAlgorithmException e) {
             e.printStackTrace();
         } catch (NoSuchPaddingException e) {
             e.printStackTrace();
         } catch (InvalidKeyException e) {
             e.printStackTrace();
         } catch (InvalidKeySpecException e) {
             e.printStackTrace();
         }
         end = System.currentTimeMillis();
         Log.d(TAG, "init Cipher needs " + (end - begin) + " ms");
     }

     byte[] des(int mode,byte data[]){

         byte[] ret = null;
         //加密的内容存在并且密钥存在且长度为8个字节
         ) {
             try {
                 //Cipher.DECRYPT_MODE 解密
                 //Cipher.ENCRYPT_MODE 加密
                 cipher.init(mode, secretKey);
                 ret = cipher.doFinal(data);

             } catch (IllegalBlockSizeException e) {
                 e.printStackTrace();
             } catch (BadPaddingException e) {
                 e.printStackTrace();
             } catch (InvalidKeyException e) {
                 e.printStackTrace();
             }
         }
         return ret;
     }

     //DES 解密
     public byte[] desDecrypt(byte data[]){
         return des(Cipher.DECRYPT_MODE,data);
     }
     //DES 加密
     public byte[] desEncrypt(byte data[]){
         return des(Cipher.ENCRYPT_MODE,data);
     }

     //byte 数组与 int 的相互转换
     public static int byteArrayToInt(byte[] b) {
         ] & 0xFF        |
                 (b[] &   |
                 (b[] &  |
                 (b[] &  ;
     }

     public static byte[] intToByteArray(int a) {
         return new byte[] {
                 ()   & 0xFF),
                 ()   & 0xFF),
                 ()    & 0xFF),
                 (byte) (a           & 0xFF)
         };
     }

     public CipherUtil(){
         init();
     }

     void testEncryptBytes(){
         ];
         ;i < data.length;++i){
             data[i] = (byte) i;
         }
         Log.d(TAG, "bytes data is  [ " + new String(data) + " ]");

         begin = System.currentTimeMillis();
         byte encrypt[] = desEncrypt(data);
         end = System.currentTimeMillis();
         Log.d(TAG, "encrypt ret is [ " + new String(encrypt) + " ] needs " + (end - begin) + " ms");

         begin = System.currentTimeMillis();
         byte decrypt[] = desDecrypt(encrypt);
         end = System.currentTimeMillis();

         Log.d(TAG, "decrypt ret is [ " + new String(decrypt) + " ] needs " + (end - begin) + " ms");

     }
     void testEncryptInt(){
         ;
         byte bytes[] = intToByteArray(data);
         Log.d(TAG, "int data is  [ " + data + " ]");

         begin = System.currentTimeMillis();
         byte encrypt[] = desEncrypt(bytes);
         end = System.currentTimeMillis();
         Log.d(TAG, "encrypt ret is [ " + new String(encrypt) + " ] needs " + (end - begin) + " ms");

         begin = System.currentTimeMillis();
         byte decrypt[] = desDecrypt(encrypt);
         end = System.currentTimeMillis();

         Log.d(TAG, "decrypt ret is [ " + byteArrayToInt(decrypt) + " ] needs " + (end - begin) + " ms");

     }
     void testEncryptString(){
         String str = "hello world";
         byte data[] = str.getBytes();
         Log.d(TAG, "string data is [ " + str + " ]");

         begin = System.currentTimeMillis();
         byte encrypt[] = desEncrypt(data);
         end = System.currentTimeMillis();
         Log.d(TAG, "encrypt ret is [ " + new String(encrypt) + " ] needs " + (end - begin) + " ms");

         begin = System.currentTimeMillis();
         byte decrypt[] = desDecrypt(encrypt);
         end = System.currentTimeMillis();

         Log.d(TAG, "decrypt ret is [ " + new String(decrypt) + " ] needs " + (end - begin) + " ms");

     }

     public void testMain(){

         Log.d(TAG, "-----=====-----------=========-----");
         testEncryptBytes();
         Log.d(TAG, "-----=====-----------=========-----");
         testEncryptInt();
         Log.d(TAG, "-----=====-----------=========-----");
         testEncryptString();
     }
 }