關鍵字：微信公眾平臺 消息體簽名 消息體加解密 EncodingAESKey 安全模式

原文 http://m.survivalescaperooms.com/txw1958/p/weixin-aes-encrypt-decrypt.html

微信公眾平臺在配置服務器時，提供了3種加解密的模式供開發者選擇，即明文模式、兼容模式、安全模式,選擇兼容模式和安全模式前，需在開發者中心填寫消息加解密密鑰EncodingAESKey。

• 明文模式：維持現有模式，沒有適配加解密新特性，消息體明文收發，默認設置為明文模式
• 兼容模式：公眾平臺發送消息內容將同時包括明文和密文，消息包長度增加到原來的3倍左右；公眾號回復明文或密文均可，不影響現有消息收發；開發者可在此模式下進行調試
• 安全模式（推薦）：公眾平臺發送消息體的內容只含有密文，公眾賬號回復的消息體也為密文，建議開發者在調試成功后使用此模式收發消息

什么是EncodingAESKey？

• 微信公眾平臺采用AES對稱加密算法對推送給公眾帳號的消息體對行加密，EncodingAESKey則是加密所用的秘鑰。公眾帳號用此秘鑰對收到的密文消息體進行解密，回復消息體也用此秘鑰加密。AES對稱加密算法的原理可以參考 http://m.survivalescaperooms.com/txw1958/p/aes.html

　　加解密的詳細技術方案可以參考官方文檔 http://mp.weixin.QQ.com/wiki/index.php?title=%E6%8A%80%E6%9C%AF%E6%96%B9%E6%A1%88

假設本次的開發配置中URL為

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

接口程序中需要配置以下三項參數

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

當用戶向公眾賬號發送消息時，微信公眾賬號將會在URL中帶上signature、timestamp、nonce、encrypt_type、msg_signature等參數，如下所示

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

同時向該接口推送如下xml消息 ，即一個已加密的消息

<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>

這時，程序需要從url中獲得以下參數

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

這些參數將用于加解密過程

收到消息后，先進行解密，解密部分代碼如下

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

解密完成后，把解密內容又返回給$postStr，這是為了保證將消息中解密后的內容和明文模式時的消息統一，方便后續處理，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>

對消息在自己的原來代碼中處理，完成之后，要回復的消息如下

<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技術支持 方倍工作室http://www.fangbei.org/]]></Content></xml>

把上述消息進行加密，返回給微信公眾賬號

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

加密后的內容如下

<xml>    <Encrypt><![CDATA[pE6gp6qvVBMHwCXwnM7illFBrh9LmvlKFlPUDuyQo9EKNunqbUFMd2KjiYoz+3K1B+93JbMWHt+19TI8awdRdyoPRS4oUNg5M2jwpwXTmc6TtafkKNjvqlvPXIWmutw0tuMXke1hDgsqz0SC8h/QjNLxECuwnczrfCMJlt+APHnX2yMMaq/aYUNcndOH387loQvl2suCGucXpglnbxf7frTCz9NQVgKiYrvKOhk6KFiVMnzuxy6WWmoe3GBiUCPTtYf5b1CxzN2IHViEBm28ilV9wWdNOM9TPG7BSSAcpgY4pcwdIG5+4KhgYmnVU3bc/ZJkk42TIdidigOfFpJwET4UWVrLB/ldUud4aPexp3aPCR3Fe53S2HHcl3tTxh4iRvDftUKP3svYPctt1MlYuYv/BZ4JyzUQV03H+0XrVyDY2tyVjimgCrA2c1mZMgHttOHTQ6VTnxrMq0GWlRlH0KPQKqtjUpNQzuOH4upQ8boPsEtuY3wDA2RaXQPJrXon]]></Encrypt>    <MsgSignature><![CDATA[6c46904dc1f58b2ddf2dd0399f1c6cf41f33ecb9]]></MsgSignature>    <TimeStamp>1414243733</TimeStamp>    <Nonce><![CDATA[1792106704]]></Nonce></xml>

這樣，一個安全模式下的加解密消息就完成了。

  1 <?php  2 /*  3     方倍工作室 http://m.survivalescaperooms.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     //驗證簽名 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     //響應消息 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                 $this->logger(" D /r/n".$postStr); 51                 $decryptMsg = "";  //解密后的明文 52                 $errCode = $pc->DecryptMsg($msg_signature, $timestamp, $nonce, $postStr, $decryptMsg); 53                 $postStr = $decryptMsg; 54             } 55             $this->logger(" R /r/n".$postStr); 56             $postObj = simplexml_load_string($postStr, 'SimpleXMLElement', LIBXML_NOCDATA); 57             $RX_TYPE = trim($postObj->MsgType); 58  59             //消息類型分離 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             $this->logger(" R /r/n".$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                 $this->logger(" E /r/n".$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 = "歡迎關注方倍工作室 "; 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             $content = "這是個文本消息";105         }else if (strstr($keyword