微信公众平台开发者中心安全模式消息体加解密实现

一、消息体加解密

微信公众平台在配置服务器时，提供了3种加解密的模式供开发者选择，即明文模式、兼容模式、安全模式,选择兼容模式和安全模式前，需在开发者中心填写消息加解密密钥EncodingAESKey。

由浙江百牛信息技术bainiu.ltd整理发布于博客园

• 明文模式：维持现有模式，没有适配加解密新特性，消息体明文收发，默认设置为明文模式
• 兼容模式：公众平台发送消息内容将同时包括明文和密文，消息包长度增加到原来的3倍左右；公众号回复明文或密文均可，不影响现有消息收发；开发者可在此模式下进行调试
• 安全模式（推荐）：公众平台发送消息体的内容只含有密文，公众账号回复的消息体也为密文，建议开发者在调试成功后使用此模式收发消息

什么是EncodingAESKey？

• 微信公众平台采用AES对称加密算法对推送给公众帐号的消息体对行加密，EncodingAESKey则是加密所用的秘钥。公众帐号用此秘钥对收到的密文消息体进行解密，回复消息体也用此秘钥加密。AES对称加密算法的原理可以参考 http://www.cnblogs.com/txw1958/p/aes.html

　　加解密的详细技术方案可以参考官方文档 http://mp.weixin.qq.com/wiki/index.php?title=%E6%8A%80%E6%9C%AF%E6%96%B9%E6%A1%88

二、开发实现及数据分析

1. 配置

假设本次的开发配置中URL为

http://www.fangbei.org/index.php

接口程序中需要配置以下三项参数

/*
    方倍工作室 http://www.cnblogs.com/txw1958/
    CopyRight 2014 All Rights Reserved
*/
define("TOKEN", "weixin");
define("AppID", "wxbad0b45542aa0b5e");
define("EncodingAESKey", "abcdefghijklmnopqrstuvwxyz0123456789ABCDEFG");
require_once('wxBizMsgCrypt.php');

2. 加解密实现

当用户向公众账号发送消息时，微信公众账号将会在URL中带上signature、timestamp、nonce、encrypt_type、msg_signature等参数，如下所示

http://www.fangbei.org/index.php?signature=35703636de2f9df2a77a662b68e521ce17c34db4&timestamp=1414243737&nonce=1792106704&encrypt_type=aes&msg_signature=6147984331daf7a1a9eed6e0ec3ba69055256154

同时向该接口推送如下XML消息 ，即一个已加密的消息

<xml>
    <ToUserName><![CDATA[gh_680bdefc8c5d]]></ToUserName>
    <Encrypt><![CDATA[MNn4+jJ/VsFh2gUyKAaOJArwEVYCvVmyN0iXzNarP3O6vXzK62ft1/KG2/XPZ4y5bPWU/jfIfQxODRQ7sLkUsrDRqsWimuhIT8Eq+w4E/28m+XDAQKEOjWTQIOp1p6kNsIV1DdC3B+AtcKcKSNAeJDr7x7GHLx5DZYK09qQsYDOjP6R5NqebFjKt/NpEl/GU3gWFwG8LCtRNuIYdK5axbFSfmXbh5CZ6Bk5wSwj5fu5aS90cMAgUhGsxrxZTY562QR6c+3ydXxb+GHI5w+qA+eqJjrQqR7u5hS+1x5sEsA7vS+bZ5LYAR3+PZ243avQkGllQ+rg7a6TeSGDxxhvLw+mxxinyk88BNHkJnyK//hM1k9PuvuLAASdaud4vzRQlAmnYOslZl8CN7gjCjV41skUTZv3wwGPxvEqtm/nf5fQ=]]></Encrypt>
</xml>

这时，程序需要从url中获得以下参数

$timestamp  = $_GET['timestamp'];
$nonce = $_GET["nonce"];
$msg_signature  = $_GET['msg_signature'];
$encrypt_type = $_GET['encrypt_type'];

这些参数将用于加解密过程

收到消息后，先进行解密，解密部分代码如下

$postStr = $GLOBALS["HTTP_RAW_POST_DATA"];
if ($encrypt_type == 'aes'){
    $pc = new WXBizMsgCrypt(TOKEN, EncodingAESKey, AppID);                
    $this->logger(" D 
".$postStr);
    $decryptMsg = "";  //解密后的明文
    $errCode = $pc->DecryptMsg($msg_signature, $timestamp, $nonce, $postStr, $decryptMsg);
    $postStr = $decryptMsg;
}

解密完成后，把解密内容又返回给$postStr，这是为了保证将消息中解密后的内容和明文模式时的消息统一，方便后续处理，解密后的XML如下

<xml>
    <ToUserName><![CDATA[gh_680bdefc8c5d]]></ToUserName>
    <FromUserName><![CDATA[oIDrpjpQ8j8mBuQ8nM26HWzNEZgg]]></FromUserName>
    <CreateTime>1414243737</CreateTime>
    <MsgType><![CDATA[text]]></MsgType>
    <Content><![CDATA[?]]></Content>
    <MsgId>6074130599188426998</MsgId>
</xml>

对消息在自己的原来代码中处理，完成之后，要回复的消息如下

<xml>
    <ToUserName><![CDATA[oIDrpjpQ8j8mBuQ8nM26HWzNEZgg]]></ToUserName>
    <FromUserName><![CDATA[gh_680bdefc8c5d]]></FromUserName>
    <CreateTime>1414243733</CreateTime>
    <MsgType><![CDATA[text]]></MsgType>
    <Content><![CDATA[2014-10-25 21:28:53
技术支持 方倍工作室
http://www.fangbei.org/]]></Content>
</xml>

把上述消息进行加密，返回给微信公众账号

//加密
if ($encrypt_type == 'aes'){
    $encryptMsg = ''; //加密后的密文
    $errCode = $pc->encryptMsg($result, $timeStamp, $nonce, $encryptMsg);
    $result = $encryptMsg;
    $this->logger(" E 
".$result);
}

加密后的内容如下

<xml>
    <Encrypt><![CDATA[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]]></Encrypt>
    <MsgSignature><![CDATA[6c46904dc1f58b2ddf2dd0399f1c6cf41f33ecb9]]></MsgSignature>
    <TimeStamp>1414243733</TimeStamp>
    <Nonce><![CDATA[1792106704]]></Nonce>
</xml>

这样，一个安全模式下的加解密消息就完成了。

三、完整代码

  1 <?php
  2 /*
  3     方倍工作室 http://www.cnblogs.com/txw1958/
  4     CopyRight 2014 All Rights Reserved
  5 */
  6 define("TOKEN", "weixin");
  7 define("AppID", "wxbad0b45542aa0b5e");
  8 define("EncodingAESKey", "abcdefghijklmnopqrstuvwxyz0123456789ABCDEFG");
  9 require_once('wxBizMsgCrypt.php');
 10 
 11 $wechatObj = new wechatCallbackapiTest();
 12 if (!isset($_GET['echostr'])) {
 13     $wechatObj->responseMsg();
 14 }else{
 15     $wechatObj->valid();
 16 }
 17 
 18 class wechatCallbackapiTest
 19 {
 20     //验证签名
 21     public function valid()
 22     {
 23         $echoStr = $_GET["echostr"];
 24         $signature = $_GET["signature"];
 25         $timestamp = $_GET["timestamp"];
 26         $nonce = $_GET["nonce"];
 27         $tmpArr = array(TOKEN, $timestamp, $nonce);
 28         sort($tmpArr);
 29         $tmpStr = implode($tmpArr);
 30         $tmpStr = sha1($tmpStr);
 31         if($tmpStr == $signature){
 32             echo $echoStr;
 33             exit;
 34         }
 35     }
 36 
 37     //响应消息
 38     public function responseMsg()
 39     {
 40         $timestamp  = $_GET['timestamp'];
 41         $nonce = $_GET["nonce"];
 42         $msg_signature  = $_GET['msg_signature'];
 43         $encrypt_type = (isset($_GET['encrypt_type']) && ($_GET['encrypt_type'] == 'aes')) ? "aes" : "raw";
 44         
 45         $postStr = $GLOBALS["HTTP_RAW_POST_DATA"];
 46         if (!empty($postStr)){
 47             //解密
 48             if ($encrypt_type == 'aes'){
 49                 $pc = new WXBizMsgCrypt(TOKEN, EncodingAESKey, AppID);                
 50                 $this->logger(" D 
".$postStr);
 51                 $decryptMsg = "";  //解密后的明文
 52                 $errCode = $pc->DecryptMsg($msg_signature, $timestamp, $nonce, $postStr, $decryptMsg);
 53                 $postStr = $decryptMsg;
 54             }
 55             $this->logger(" R 
".$postStr);
 56             $postObj = simplexml_load_string($postStr, 'SimpleXMLElement', LIBXML_NOCDATA);
 57             $RX_TYPE = trim($postObj->MsgType);
 58 
 59             //消息类型分离
 60             switch ($RX_TYPE)
 61             {
 62                 case "event":
 63                     $result = $this->receiveEvent($postObj);
 64                     break;
 65                 case "text":
 66                     $result = $this->receiveText($postObj);
 67                     break;
 68             }
 69             $this->logger(" R 
".$result);
 70             //加密
 71             if ($encrypt_type == 'aes'){
 72                 $encryptMsg = ''; //加密后的密文
 73                 $errCode = $pc->encryptMsg($result, $timeStamp, $nonce, $encryptMsg);
 74                 $result = $encryptMsg;
 75                 $this->logger(" E 
".$result);
 76             }
 77             echo $result;
 78         }else {
 79             echo "";
 80             exit;
 81         }
 82     }
 83 
 84     //接收事件消息
 85     private function receiveEvent($object)
 86     {
 87         $content = "";
 88         switch ($object->Event)
 89         {
 90             case "subscribe":
 91                 $content = "欢迎关注方倍工作室 ";
 92                 break;
 93         }
 94 
 95         $result = $this->transmitText($object, $content);
 96         return $result;
 97     }
 98 
 99     //接收文本消息
100     private function receiveText($object)
101     {
102         $keyword = trim($object->Content);
103         if (strstr($keyword, "文本")){
104             $content = "这是个文本消息";
105         }else if (strstr($keyword, "单图文")){
106             $content = array();
107             $content[] = array("Title"=>"单图文标题",  "Description"=>"单图文内容", "PicUrl"=>"http://discuz.comli.com/weixin/weather/icon/cartoon.jpg", "Url" =>"http://m.cnblogs.com/?u=txw1958");
108         }else if (strstr($keyword, "图文") || strstr($keyword, "多图文")){
109             $content = array();
110             $content[] = array("Title"=>"多图文1标题", "Description"=>"", "PicUrl"=>"http://discuz.comli.com/weixin/weather/icon/cartoon.jpg", "Url" =>"http://m.cnblogs.com/?u=txw1958");
111             $content[] = array("Title"=>"多图文2标题", "Description"=>"", "PicUrl"=>"http://d.hiphotos.bdimg.com/wisegame/pic/item/f3529822720e0cf3ac9f1ada0846f21fbe09aaa3.jpg", "Url" =>"http://m.cnblogs.com/?u=txw1958");
112             $content[] = array("Title"=>"多图文3标题", "Description"=>"", "PicUrl"=>"http://g.hiphotos.bdimg.com/wisegame/pic/item/18cb0a46f21fbe090d338acc6a600c338644adfd.jpg", "Url" =>"http://m.cnblogs.com/?u=txw1958");
113         }else if (strstr($keyword, "音乐")){
114             $content = array();
115             $content = array("Title"=>"最炫民族风", "Description"=>"歌手：凤凰传奇", "MusicUrl"=>"http://121.199.4.61/music/zxmzf.mp3", "HQMusicUrl"=>"http://121.199.4.61/music/zxmzf.mp3");
116         }else{
117             $content = date("Y-m-d H:i:s",time())."
".$object->FromUserName."
技术支持 方倍工作室";
118         }
119 
120         if(is_array($content)){
121             if (isset($content[0])){
122                 $result = $this->transmitNews($object, $content);
123             }else if (isset($content['MusicUrl'])){
124                 $result = $this->transmitMusic($object, $content);
125             }
126         }else{
127             $result = $this->transmitText($object, $content);
128         }
129         return $result;
130     }
131 
132     //回复文本消息
133     private function transmitText($object, $content)
134     {
135         $xmlTpl = "<xml>
136     <ToUserName><![CDATA[%s]]></ToUserName>
137     <FromUserName><![CDATA[%s]]></FromUserName>
138     <CreateTime>%s</CreateTime>
139     <MsgType><![CDATA[text]]></MsgType>
140     <Content><![CDATA[%s]]></Content>
141 </xml>";
142         $result = sprintf($xmlTpl, $object->FromUserName, $object->ToUserName, time(), $content);
143         return $result;
144     }
145 
146     //回复图文消息
147     private function transmitNews($object, $newsArray)
148     {
149         if(!is_array($newsArray)){
150             return;
151         }
152         $itemTpl = "        <item>
153             <Title><![CDATA[%s]]></Title>
154             <Description><![CDATA[%s]]></Description>
155             <PicUrl><![CDATA[%s]]></PicUrl>
156             <Url><![CDATA[%s]]></Url>
157         </item>
158 ";
159         $item_str = "";
160         foreach ($newsArray as $item){
161             $item_str .= sprintf($itemTpl, $item['Title'], $item['Description'], $item['PicUrl'], $item['Url']);
162         }
163         $xmlTpl = "<xml>
164     <ToUserName><![CDATA[%s]]></ToUserName>
165     <FromUserName><![CDATA[%s]]></FromUserName>
166     <CreateTime>%s</CreateTime>
167     <MsgType><![CDATA[news]]></MsgType>
168     <ArticleCount>%s</ArticleCount>
169     <Articles>
170 $item_str    </Articles>
171 </xml>";
172 
173         $result = sprintf($xmlTpl, $object->FromUserName, $object->ToUserName, time(), count($newsArray));
174         return $result;
175     }
176 
177     //回复音乐消息
178     private function transmitMusic($object, $musicArray)
179     {
180         $itemTpl = "<Music>
181         <Title><![CDATA[%s]]></Title>
182         <Description><![CDATA[%s]]></Description>
183         <MusicUrl><![CDATA[%s]]></MusicUrl>
184         <HQMusicUrl><![CDATA[%s]]></HQMusicUrl>
185     </Music>";
186 
187         $item_str = sprintf($itemTpl, $musicArray['Title'], $musicArray['Description'], $musicArray['MusicUrl'], $musicArray['HQMusicUrl']);
188 
189         $xmlTpl = "<xml>
190     <ToUserName><![CDATA[%s]]></ToUserName>
191     <FromUserName><![CDATA[%s]]></FromUserName>
192     <CreateTime>%s</CreateTime>
193     <MsgType><![CDATA[music]]></MsgType>
194     $item_str
195 </xml>";
196 
197         $result = sprintf($xmlTpl, $object->FromUserName, $object->ToUserName, time());
198         return $result;
199     }
200 
201     //日志记录
202     public function logger($log_content)
203     {
204         if(isset($_SERVER['HTTP_APPNAME'])){   //SAE
205             sae_set_display_errors(false);
206             sae_debug($log_content);
207             sae_set_display_errors(true);
208         }else if($_SERVER['REMOTE_ADDR'] != "127.0.0.1"){ //LOCAL
209             $max_size = 500000;
210             $log_filename = "log.xml";
211             if(file_exists($log_filename) and (abs(filesize($log_filename)) > $max_size)){unlink($log_filename);}
212             file_put_contents($log_filename, date('Y-m-d H:i:s').$log_content."
", FILE_APPEND);
213         }
214     }
215 }
216 ?>