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;
    byte key[] = new byte[]{'c','B','z',2,'b','y','d',8};

    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
        if (data != null && data.length > 0) {
            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) {
        return   b[3] & 0xFF        |
                (b[2] & 0xFF) << 8  |
                (b[1] & 0xFF) << 16 |
                (b[0] & 0xFF) << 24 ;
    }

    public static byte[] intToByteArray(int a) {
        return new byte[] {
                (byte) ((a >> 24)   & 0xFF),
                (byte) ((a >> 16)   & 0xFF),
                (byte) ((a >> 8)    & 0xFF),
                (byte) (a           & 0xFF)
        };
    }

    public CipherUtil(){
        init();
    }

    void testEncryptBytes(){
        byte data[] = new byte[16];
        for (int i = 0;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(){
        int data = 100;
        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();
    }
}