thinkphp微信开发：安全模式消息加解密
使用thinkphp官方的WeChat包，使用不同模式可以成功，但是安全模式就是不行，现将分析解决结果做下记录。
TRight
分析问题：
解密微信服务器消息老是不成功，下载下微信公众平台官方给出的解密文件和WechatCrypt.class.php进行比对发现也没有问题。用file_put_contents函数保存下解密后的文件进行分析。发现官方包解密的xml不是标准的xml格式，所以simplexml_load_string函数无法处理。
<span style="color: #008000;">/*</span><span style="color: #008000;">* * 对密文进行解密 * @param string $encrypt 密文 * @return string 明文 </span><span style="color: #008000;">*/</span> <span style="color: #0000ff;">public</span> <span style="color: #0000ff;">function</span> decrypt(<span style="color: #800080;">$encrypt</span><span style="color: #000000;">){ </span><span style="color: #008000;">//</span><span style="color: #008000;">BASE64解码</span> <span style="color: #800080;">$encrypt</span> = <span style="color: #008080;">base64_decode</span>(<span style="color: #800080;">$encrypt</span><span style="color: #000000;">); </span><span style="color: #008000;">//</span><span style="color: #008000;">打开加密算法模块</span> <span style="color: #800080;">$td</span> = mcrypt_module_open(MCRYPT_RIJNDAEL_128, '', MCRYPT_MODE_CBC, ''<span style="color: #000000;">); </span><span style="color: #008000;">//</span><span style="color: #008000;">初始化加密算法模块</span> mcrypt_generic_init(<span style="color: #800080;">$td</span>, <span style="color: #800080;">$this</span>->cyptKey, <span style="color: #008080;">substr</span>(<span style="color: #800080;">$this</span>->cyptKey, 0, 16<span style="color: #000000;">)); </span><span style="color: #008000;">//</span><span style="color: #008000;">执行解密</span> <span style="color: #800080;">$decrypt</span> = mdecrypt_generic(<span style="color: #800080;">$td</span>, <span style="color: #800080;">$encrypt</span><span style="color: #000000;">); </span><span style="color: #008000;">//</span><span style="color: #008000;">去除PKCS7补位</span> <span style="color: #800080;">$decrypt</span> = self::PKCS7Decode(<span style="color: #800080;">$decrypt</span>, mcrypt_enc_get_key_size(<span style="color: #800080;">$td</span><span style="color: #000000;">)); </span><span style="color: #008000;">//</span><span style="color: #008000;">关闭加密算法模块</span> mcrypt_generic_deinit(<span style="color: #800080;">$td</span><span style="color: #000000;">); mcrypt_module_close(</span><span style="color: #800080;">$td</span><span style="color: #000000;">); </span><span style="color: #0000ff;">if</span>(<span style="color: #008080;">strlen</span>(<span style="color: #800080;">$decrypt</span>) ){ <span style="color: #0000ff;">throw</span> <span style="color: #0000ff;">new</span> \<span style="color: #0000ff;">Exception</span>("非法密文字符串！"<span style="color: #000000;">); } </span><span style="color: #008000;">//</span><span style="color: #008000;">去除随机字符串</span> <span style="color: #800080;">$decrypt</span> = <span style="color: #008080;">substr</span>(<span style="color: #800080;">$decrypt</span>, 16<span style="color: #000000;">); </span><span style="color: #008000;">//</span><span style="color: #008000;">获取网络字节序</span> <span style="color: #800080;">$size</span> = <span style="color: #008080;">unpack</span>("N", <span style="color: #008080;">substr</span>(<span style="color: #800080;">$decrypt</span>, 0, 4<span style="color: #000000;">)); </span><span style="color: #800080;">$size</span> = <span style="color: #800080;">$size</span>[1<span style="color: #000000;">]; </span><span style="color: #008000;">//</span><span style="color: #008000;">APP_ID</span> <span style="color: #800080;">$appid</span> = <span style="color: #008080;">substr</span>(<span style="color: #800080;">$decrypt</span>, <span style="color: #800080;">$size</span> + 4<span style="color: #000000;">); </span><span style="color: #008000;">//</span><span style="color: #008000;">验证APP_ID</span> <span style="color: #0000ff;">if</span>(<span style="color: #800080;">$appid</span> !== <span style="color: #800080;">$this</span>-><span style="color: #000000;">appId){ </span><span style="color: #0000ff;">throw</span> <span style="color: #0000ff;">new</span> \<span style="color: #0000ff;">Exception</span>("非法APP_ID！"<span style="color: #000000;">); } </span><span style="color: #008000;">//</span><span style="color: #008000;">明文内容</span> <span style="color: #800080;">$text</span> = <span style="color: #008080;">substr</span>(<span style="color: #800080;">$decrypt</span>, 4, <span style="color: #800080;">$size</span><span style="color: #000000;">); </span><span style="color: #0000ff;">return</span> <span style="color: #800080;">$text</span><span style="color: #000000;">; } </span><span style="color: #008000;">/*</span><span style="color: #008000;">* * PKCS7填充字符 * @param string $text 被填充字符 * @param integer $size Block长度 </span><span style="color: #008000;">*/</span> <span style="color: #0000ff;">private</span> <span style="color: #0000ff;">static</span> <span style="color: #0000ff;">function</span> PKCS7Encode(<span style="color: #800080;">$text</span>, <span style="color: #800080;">$size</span><span style="color: #000000;">){ </span><span style="color: #008000;">//</span><span style="color: #008000;">字符串长度</span> <span style="color: #800080;">$str_size</span> = <span style="color: #008080;">strlen</span>(<span style="color: #800080;">$text</span><span style="color: #000000;">); </span><span style="color: #008000;">//</span><span style="color: #008000;">填充长度</span> <span style="color: #800080;">$pad_size</span> = <span style="color: #800080;">$size</span> - (<span style="color: #800080;">$str_size</span> % <span style="color: #800080;">$size</span><span style="color: #000000;">); </span><span style="color: #800080;">$pad_size</span> = <span style="color: #800080;">$pad_size</span> ? : <span style="color: #800080;">$size</span><span style="color: #000000;">; </span><span style="color: #008000;">//</span><span style="color: #008000;">填充的字符</span> <span style="color: #800080;">$pad_chr</span> = <span style="color: #008080;">chr</span>(<span style="color: #800080;">$pad_size</span><span style="color: #000000;">); </span><span style="color: #008000;">//</span><span style="color: #008000;">执行填充</span> <span style="color: #800080;">$text</span> = <span style="color: #008080;">str_pad</span>(<span style="color: #800080;">$text</span>, <span style="color: #800080;">$str_size</span> + <span style="color: #800080;">$pad_size</span>, <span style="color: #800080;">$pad_chr</span>,<span style="color: #000000;"> STR_PAD_RIGHT); </span><span style="color: #0000ff;">return</span> <span style="color: #800080;">$text</span><span style="color: #000000;">; } </span><span style="color: #008000;">/*</span><span style="color: #008000;">* * 删除PKCS7填充的字符 * @param string $text 已填充的字符 * @param integer $size Block长度 </span><span style="color: #008000;">*/</span> <span style="color: #0000ff;">private</span> <span style="color: #0000ff;">static</span> <span style="color: #0000ff;">function</span> PKCS7Decode(<span style="color: #800080;">$text</span>, <span style="color: #800080;">$size</span><span style="color: #000000;">){ </span><span style="color: #008000;">//</span><span style="color: #008000;">获取补位字符</span> <span style="color: #800080;">$pad_str</span> = <span style="color: #008080;">ord</span>(<span style="color: #008080;">substr</span>(<span style="color: #800080;">$text</span>, -1<span style="color: #000000;">)); </span><span style="color: #0000ff;">if</span> (<span style="color: #800080;">$pad_str</span> $pad_str > <span style="color: #800080;">$size</span><span style="color: #000000;">) { </span><span style="color: #800080;">$pad_str</span>= 0<span style="color: #000000;">; } </span><span style="color: #0000ff;">return</span> <span style="color: #008080;">substr</span>(<span style="color: #800080;">$text</span>, 0, <span style="color: #008080;">strlen</span>(<span style="color: #800080;">$text</span>) - <span style="color: #800080;">$pad_str</span><span style="color: #000000;">); }</span>输出的xml文件是这样的
<span style="color: #008080;">1</span> <span style="color: #0000ff;"><span style="color: #800000;">xml</span><span style="color: #0000ff;">></span><span style="color: #008080;">2</span> <span style="color: #0000ff;"><span style="color: #800000;">ToUserName</span><span style="color: #0000ff;">></span><span style="color: #0000ff;"><span style="color: #808080;">gh_249aeb986d99</span><span style="color: #0000ff;">]]></span><span style="color: #0000ff;"><span style="color: #800000;">\/ToUserName</span><span style="color: #0000ff;">></span><span style="color: #000000;">\n</span><span style="color: #008080;">3</span> <span style="color: #0000ff;"><span style="color: #800000;">FromUserName</span><span style="color: #0000ff;">></span><span style="color: #0000ff;"><span style="color: #808080;">oopVmxHZaeQkDPsRcbpwXKkH-J2Q</span><span style="color: #0000ff;">]]></span><span style="color: #0000ff;"><span style="color: #800000;">\/FromUserName</span><span style="color: #0000ff;">></span><span style="color: #000000;">\n</span><span style="color: #008080;">4</span> <span style="color: #0000ff;"><span style="color: #800000;">CreateTime</span><span style="color: #0000ff;">></span>1448944621<span style="color: #0000ff;"><span style="color: #800000;">\/CreateTime</span><span style="color: #0000ff;">></span><span style="color: #000000;">\n</span><span style="color: #008080;">5</span> <span style="color: #0000ff;"><span style="color: #800000;">MsgType</span><span style="color: #0000ff;">></span><span style="color: #0000ff;"><span style="color: #808080;">text</span><span style="color: #0000ff;">]]></span><span style="color: #0000ff;"><span style="color: #800000;">\/MsgType</span><span style="color: #0000ff;">></span><span style="color: #000000;">\n</span><span style="color: #008080;">6</span> <span style="color: #0000ff;"><span style="color: #800000;">Content</span><span style="color: #0000ff;">></span><span style="color: #0000ff;"><span style="color: #808080;">\u7ecf\u7406</span><span style="color: #0000ff;">]]></span><span style="color: #0000ff;"><span style="color: #800000;">\/Content</span><span style="color: #0000ff;">></span><span style="color: #000000;">\n</span><span style="color: #008080;">7</span> <span style="color: #0000ff;"><span style="color: #800000;">MsgId</span><span style="color: #0000ff;">></span>6223169761311044588<span style="color: #0000ff;"><span style="color: #800000;">\/MsgId</span><span style="color: #0000ff;">></span><span style="color: #000000;">\n</span><span style="color: #008080;">8</span> <span style="color: #0000ff;"><span style="color: #800000;">\/xml</span><span style="color: #0000ff;">></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span>
所以需要进行处理才能让simplexml_load_string处理
在输出的明文内容后面加上
<span style="color: #008080;">1</span> <span style="color: #000000;">//明文内容</span><span style="color: #008080;">2</span> <span style="color: #000000;"> $text = substr($decrypt, 4, $size);</span><span style="color: #008080;">3</span> <span style="color: #000000;">//去掉多余的内容</span><span style="color: #008080;">4</span> $text=str_replace('<span style="color: #0000ff;"><span style="color: #800000;">\/','', $text</span><span style="color: #ff0000;">); </span><span style="color: #008080;">5</span> <span style="color: #ff0000;"> $text</span><span style="color: #0000ff;">=str_replace('>\n','>', </span><span style="color: #ff0000;">$text);</span><span style="color: #008080;">6</span> <span style="color: #ff0000;"> return $text;</span></span>
安全模式就能正常使用了。
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