Share an example tutorial on data decryption in WeChat development

Recently I am using the thinkphp framework to write the server side of the WeChat applet. Perhaps it is because of Virgo that I downloaded a PHP WeChat decryption demo from the official website. It can be integrated into a class without much code, so I have to It is written in several categories. Considering that the thinkphp 5.0 framework seems too painful for extended class references, it is integrated into one class for easy calling. Friends in need can download it.

##Baidu disk download address:

pan.baidu.com/s/1kURMQ2b

<?php
/**
 * 对微信小程序用户加密数据的解密示例代码.
 *
 * @copyright Copyright (c) 1998-2014 Tencent Inc.
 */

class WXBizDataCrypt
{
    private $appid;
    private $sessionKey;
    private $blockSize = 16;

    private $OKs = 0;
    private $IllegalAesKey = -41001;
    private $IllegalIv = -41002;
    private $IllegalBuffer = -41003;
    private $DecodeBase64Error = -41004;

    /**
     * 检验数据的真实性，并且获取解密后的明文.
     * @param $encryptedData string 加密的用户数据
     * @param $iv string 与用户数据一同返回的初始向量
     * @param $data string 解密后的原文
     *
     * @return int 成功0，失败返回对应的错误码
     */
    public function decryptData($appid,$sessionKey,$encryptedData, $iv, &$data )
    {
        $this->sessionKey = $sessionKey;
        $this->appid = $appid;

        if (strlen($this->sessionKey) != 24) {
            return $this->IllegalAesKey;
        }
        $aesKey=base64_decode($this->sessionKey);

        if (strlen($iv) != 24) {
            return $this->IllegalIv;
        }
        $aesIV=base64_decode($iv);

        $aesCipher=base64_decode($encryptedData);

        $result = $this->decrypt($aesKey,$aesCipher,$aesIV);

        if ($result[0] != 0) {
            return $result[0];
        }

        $dataObj=json_decode( $result[1] );

        if( $dataObj  == NULL )
        {
            return $this->IllegalBuffer;
        }
        if( $dataObj->watermark->appid != $this->appid )
        {
            return $this->IllegalBuffer;
        }
        $data = $result[1];
        return $this->OKs;
    }

    /**
     * 对密文进行解密
     * @param string $aesCipher 需要解密的密文
     * @param string $aesIV 解密的初始向量
     * @return string 解密得到的明文
     */
    private function decrypt($key, $aesCipher, $aesIV )
    {
        try {

            $module = mcrypt_module_open(MCRYPT_RIJNDAEL_128, &#39;&#39;, MCRYPT_MODE_CBC, &#39;&#39;);

            mcrypt_generic_init($module, $key, $aesIV);

            //解密
            $decrypted = mdecrypt_generic($module, $aesCipher);
            mcrypt_generic_deinit($module);
            mcrypt_module_close($module);
        } catch (Exception $e) {
            return array($this->IllegalBuffer, null);
        }


        try {
            //去除补位字符
            $result = $this->decode($decrypted);

        } catch (Exception $e) {
            //print $e;
            return array($this->IllegalBuffer, null);
        }
        return array(0, $result);
    }

    /**
     * 对需要加密的明文进行填充补位
     * @param $text 需要进行填充补位操作的明文
     * @return 补齐明文字符串
     */
    private function encode( $text )
    {
        $block_size = $this->blockSize;
        $text_length = strlen( $text );
        //计算需要填充的位数
        $amount_to_pad = $this->blockSize - ( $text_length % $this->blockSize );
        if ( $amount_to_pad == 0 ) {
            $amount_to_pad = $this->blockSize;
        }
        //获得补位所用的字符
        $pad_chr = chr( $amount_to_pad );
        $tmp = "";
        for ( $index = 0; $index < $amount_to_pad; $index++ ) {
            $tmp .= $pad_chr;
        }
        return $text . $tmp;
    }

    /**
     * 对解密后的明文进行补位删除
     * @param decrypted 解密后的明文
     * @return 删除填充补位后的明文
     */
    private function decode($text)
    {

        $pad = ord(substr($text, -1));
        if ($pad < 1 || $pad > 32) {
            $pad = 0;
        }
        return substr($text, 0, (strlen($text) - $pad));
    }

}

If necessary, please download it yourself. ps: If you are confused about the WeChat login authorization process, you can leave a message for consultation.

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