关键字：微信公众平台 消息体签名 消息体加解密 EncodingAESKey 安全模式
原文
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。
- 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×tamp=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
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); $this->logger(" D \r\n".$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
1414243737 6074130599188426998
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
1414243733
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; $this->logger(" E \r\n".$result);} 加密后的内容如下
1414243733
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 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 $this->logger(" D \r\n".$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 $this->logger(" R \r\n".$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 = "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 $content = date("Y-m-d H:i:s",time())."\n".$object->FromUserName."\n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 = " 136 137 138 %s 139 140 141 ";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 = " - 153
<![CDATA[%s]]> 154 155 156 157 158 ";159 $item_str = "";160 foreach ($newsArray as $item){161 $item_str .= sprintf($itemTpl, $item['Title'], $item['Description'], $item['PicUrl'], $item['Url']);162 }163 $xmlTpl = " 164 165 166 %s 167 168 %s 169 170 $item_str 171 ";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 = " 181 <![CDATA[%s]]> 182 183 184 185 ";186 187 $item_str = sprintf($itemTpl, $musicArray['Title'], $musicArray['Description'], $musicArray['MusicUrl'], $musicArray['HQMusicUrl']);188 189 $xmlTpl = " 190 191 192 %s 193 194 $item_str195 ";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($_SERVER['HTTP_APPNAME'])){ //SAE205 sae_set_display_errors(false);206 sae_debug($log_content);207 sae_set_display_errors(true);208 }else if($_SERVER['REMOTE_ADDR'] != "127.0.0.1"){ //LOCAL209 $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."\r\n", FILE_APPEND);213 }214 }215 }216 ?>