Cocos2d-x数据加密解密详解

C++的Base64算法实现

/* * base64.cpp * *  Created on: 30/04/2011 *      Author: nicholas */#include "base64.h"#include <cctype>//#include <cstdint>#include <algorithm>namespace base64{namespace{static const std::string BASE64_CHARS = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/";size_t encoded_size(size_t raw){switch((raw*8)%6){case 0:return (raw*8)/6;case 2:return ((raw*8)/6) + 3;case 4:return ((raw*8)/6) + 2;}return raw;}size_t decoded_size(size_t unpadded){return (unpadded*6)/8;}int base64_index(std::string::value_type c){if(c >= 'A' && c <= 'Z')return c-'A';else if(c >= 'a' && c <= 'z')return c-'a' + 26;else if(c >= '0' && c <= '9')return c-'0' + 52;else if(c == '+')return 62;else if(c == '/')return 63;elsereturn -1;}}encode_t::encode_t(std::string::size_type size) : state(zero), remainder(0){encoded.reserve(encoded_size(size));}/*State zero8 bits input, zero remaining from last6 bits consumed, 2 remaining=> twoState two8 bits input, 2 remaining from last4 bits consumed, 4 remaining=> fourState four8 bits input, 4 remaining from last2 bits consumed, 6 remaining6 bits input, 6 remaining from last6 bits consumed, 0 remaining=> zero */void encode_t::operator() (std::string::value_type c){unsigned char value(0);switch(state){case zero:value = (c & 0xfc) >> 2;remainder = c & 0x3;encoded.push_back(BASE64_CHARS[value]);state = two;break;case two:value = (remainder << 4) | ((c & 0xf0) >> 4);remainder = c & 0xf;encoded.push_back(BASE64_CHARS[value]);state = four;break;case four:value = (remainder << 2) | ((c & 0xc0) >> 6);remainder = c & 0x3f;encoded.push_back(BASE64_CHARS[value]);value = remainder;encoded.push_back(BASE64_CHARS[value]);state = zero;break;}}std::string encode_t::str(){unsigned char value(0);switch(state){case zero:break;case two:value = remainder << 4;encoded.push_back(BASE64_CHARS[value]);encoded.push_back('=');encoded.push_back('=');state = zero;break;case four:value = remainder << 2;encoded.push_back(BASE64_CHARS[value]);encoded.push_back('=');state = zero;break;}return encoded;}decode_t::decode_t(std::string::size_type size) : state(zero), remainder(0){decoded.reserve(decoded_size(size));}/*State zero6 bits input, zero remaining from last6 bits consumed, zero remaining=> sixState six6 bits input, 6 remaining from lastwrite 1 byte, 4 remaining=> fourState four6 bits input, 4 remaining from lastwrite 1 byte, 2 remaining=> twoState two6 bits input, 2 remaining from lastwrite 1 byte, 0 remaining=> zero */void decode_t::operator() (std::string::value_type c){unsigned char value(0);int index = base64_index(c);if(index == -1)return;switch(state){case zero:remainder = index;state = six;break;case six:value = (remainder << 2) | ((index & 0x30) >> 4);remainder = index & 0xf;decoded.push_back(value);state = four;break;case four:value = (remainder << 4) | ((index & 0x3c) >> 2);remainder = index & 0x3;decoded.push_back(value);state = two;break;case two:value = (remainder << 6) | index;decoded.push_back(value);state = zero;break;}}std::string decode_t::str() const{return decoded;}std::string encode(const std::string& str){return std::for_each(str.begin(), str.end(), encode_t(str.size())).str();}std::string decode(const std::string& str){size_t unpadded_size = str.size();if(str.size() > 0 && str[str.size()-1] == '=')unpadded_size -= 1;if(str.size() > 1 && str[str.size()-2] == '=')unpadded_size -= 1;return std::for_each(str.begin(), str.end(), decode_t(unpadded_size)).str();}}

/* * base64.h * *  Created on: 30/04/2011 *      Author: nicholas */#ifndef BASE64_H_#define BASE64_H_#include <string>namespace base64{class encode_t{private:enum{zero = 0,two,four} state;unsigned int remainder;std::string encoded;public:encode_t(std::string::size_type size);void operator() (std::string::value_type c);std::string str();};class decode_t{private:enum{zero = 0,six,four,two} state;unsigned int remainder;std::string decoded;public:decode_t(std::string::size_type size);void operator() (std::string::value_type c);std::string str() const;};/* * Encode the given string @str into its base64 representation */std::string encode(const std::string& str);/* * Decode the base64 encoded string @str */std::string decode(const std::string& str);}#endif /* BASE64_H_ */

#include<iostream>#include"base64.h"using namespace std;int main (){    string str = "abcdefghijklmn.";    string out = base64::encode(str);        cout<<"src:"<<str<<endl;     cout<<"encode: "<<out<<endl;    cout<<"decode: "<<base64::decode(out)<<endl;              str = "中文.";    out = base64::encode(str);        cout<<endl<<"src:"<<str<<endl;    cout<<"encode: "<< out <<endl;    cout<<"decode: "<< base64::decode(out) <<endl;         system("pause");    return 1;    }

Android平台下使用Base64算法加密解密数据

import com.example.base64.R;import android.app.Activity;import android.os.Bundle;import android.util.Base64;public class MainActivity extends Activity {    @Override    protected void onCreate(Bundle savedInstanceState) {        super.onCreate(savedInstanceState);        setContentView(R.layout.main);        String src = "abcdefjhijklmn.";        // 加密数据        String encode = Base64.encodeToString(src.getBytes(), Base64.DEFAULT);        // 解密数据        String decode = new String(Base64.decode(encode, Base64.DEFAULT));        System.out.println("src：" + src);        System.out.println("encode：" + encode);        System.out.println("decode：" + decode);    }}

数据库数据项加密

Cocos2d-x中操作数据库的实现都封装在LocalStorage这个类中。使用的是sqlite3。

iOS、Win32平台的加密

1.base64.h和base64.cpp添加项目Classes目录下。

2.右键libExtensions项目，附加包含目录，把base64库所在目录添加到包含目录中，具体路径根据自己项目结构而定

3.修改localStorageSetItem方法，保存数据时加密数据，这里在win32平台下忽略加密操作是因为一般win32平台版本是用于内部测试的

void localStorageSetItem( const char *key, const char *value)  {      assert( _initialized );         // 加密数据      #if (CC_TARGET_PLATFORM != CC_PLATFORM_WIN32)          //CCLOG("key=%s src=%s", key, value);                 std::string encodeStr = base64::encode(value);          value = encodeStr.c_str();          //CCLOG("key=%s encode=%s", key, value);      #endif             int ok = sqlite3_bind_text(_stmt_update, 1, key, -1, SQLITE_TRANSIENT);      ok |= sqlite3_bind_text(_stmt_update, 2, value, -1, SQLITE_TRANSIENT);         ok |= sqlite3_step(_stmt_update);             ok |= sqlite3_reset(_stmt_update);             if( ok != SQLITE_OK && ok != SQLITE_DONE)          printf("Error in localStorage.setItem()\n");  }

4.修改localStorageGetItem方法，获取数据时解密数据

const char* localStorageGetItem( const char *key )  {      assert( _initialized );         int ok = sqlite3_reset(_stmt_select);         ok |= sqlite3_bind_text(_stmt_select, 1, key, -1, SQLITE_TRANSIENT);      ok |= sqlite3_step(_stmt_select);      const unsigned char *ret = sqlite3_column_text(_stmt_select, 0);                if( ok != SQLITE_OK && ok != SQLITE_DONE && ok != SQLITE_ROW)          printf("Error in localStorage.getItem()\n");         // 加密数据      #if (CC_TARGET_PLATFORM != CC_PLATFORM_WIN32)          //CCLOG("decode src=%s", ret);            if (ret)          {              std::string decodeStr = base64::decode((const char*)ret);                                                    char* c = new char;                           strcpy_s(c, decodeStr.size() + 1, decodeStr.c_str());                //CCLOG("key=%s decode=%s", key, c);                          return c;          }             #endif         return (const char*)ret;  }

注意：c_str()方法返回的是string对象中保留的字符串指针，该指针的生命周期是跟随string对象的。也就是如果直接返回decodeStr.c_str()，返回的将是垃圾数据，因为decodeStr在函数结束后，已经被销毁了，指针所指向的是垃圾数据。

这种数据库加密方案存在以下几个问题：

1.如果别人知道我所使用的加密算法，然后通过程序计算出加密串，还是可以修改成功的。

2.数据库还是可以用相关工具打开，并查看数据表。

3.每次读写数据时，增加了加密解密的步骤，降低效率。

对于Cocos2d-x中数据库的加密有更好的解决办法，就是使用wxsqlite3，点击查看【集成wxSqlite3到Cocos2d-x】，这种数据库加密的实现是在初始化数据库的时候加密，运行时加载数据库时候调用相关api解密，加载完成后数据的读写效率和未加密时一样，相对比较高效。

Android平台的加密

从LocalStorage.cpp中使用的宏可以看出，这个实现在安卓平台下是无法使用的。

安卓平台下的实现在：cocos2d-x-2.1.5\extensions\LocalStorage目录下的LocalStorageAndroid.cpp中。

从localStrorageInit的实现可以看出，它是通过jni调用了java层中org/cocos2dx/lib/Cocos2dxLocalStorage的静态方法init。

在打包安卓版Cocos2d-x游戏时需要用到引擎的一个java库，在cocos2d-x-2.1.5\cocos2dx\platform\android\java目录下，Cocos2dxLocalStorage类就在这个库中。

修改这个类的setItem方法，在保存数据的时候加密

public static void setItem(String key, String value) {      try {          // 加密数据          value = Base64.encodeToString(value.getBytes(), Base64.DEFAULT);             String sql = "replace into " + TABLE_NAME                  + "(key,value)values(?,?)";          mDatabase.execSQL(sql, new Object[] { key, value });      } catch (Exception e) {          e.printStackTrace();      }  }

修改这个类的getItem方法，在获取数据的时候解密

public static String getItem(String key) {      String ret = null;      try {          String sql = "select value from " + TABLE_NAME + " where key=?";          Cursor c = mDatabase.rawQuery(sql, new String[] { key });          while (c.moveToNext()) {              // only return the first value              if (ret != null) {                  Log.e(TAG, "The key contains more than one value.");                  break;              }              ret = c.getString(c.getColumnIndex("value"));          }          c.close();      } catch (Exception e) {          e.printStackTrace();      }             // 解密数据      if (ret != null) {          ret = new String(Base64.decode(ret, Base64.DEFAULT));      }             return ret == null ? "" : ret;  }

来源网址：http://blog.csdn.net/linchaolong/article/details/41224483