请教：微信消息加密算法中用openssl_decrypt替换mcrypt_module 失败的问题

这是我曾经踩过的坑，下面我自己调试成功的代码。供你借鉴下

<?php

include_once "errorCode.php";

/**
 * PKCS7Encoder class
 *
 * 提供基于PKCS7算法的加解密接口.
 */
class PKCS7Encoder
{
    public static $block_size = 32;

    /**
     * 对需要加密的明文进行填充补位
     * @param $text 需要进行填充补位操作的明文
     * @return 补齐明文字符串
     */
    function encode($text)
    {
        $block_size = PKCS7Encoder::$block_size;
        $text_length = strlen($text);
        //计算需要填充的位数
        $amount_to_pad = PKCS7Encoder::$block_size - ($text_length % PKCS7Encoder::$block_size);
        if ($amount_to_pad == 0) {
            $amount_to_pad = PKCS7Encoder::block_size;
        }
        //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
     */
    function decode($text)
    {

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

}

/**
 * Prpcrypt class
 *
 * 提供接收和推送给公众平台消息的加解密接口.
 */
class Prpcrypt
{
    public $key;

    function __construct($k)
    {
        $this->key = base64_decode($k . "=");
    }

    /**
     * 对明文进行加密
     * @param string $text 需要加密的明文
     * @return string 加密后的密文
     */
    public function encrypt($text, $appid)
    {

        try {
            $random = $this->getRandomStr();//"aaaabbbbccccdddd";
            $text = $random . pack("N", strlen($text)) . $text . $appid;
            $iv = substr($this->key, 0, 16);
            $pkc_encoder = new PKCS7Encoder;
            $text = $pkc_encoder->encode($text);
            $encrypted = openssl_encrypt($text,'AES-256-CBC',substr($this->key, 0, 32),OPENSSL_ZERO_PADDING,$iv);
            return array(ErrorCode::$OK, $encrypted);
        } catch (Exception $e) {
            //print $e;
            return array(ErrorCode::$EncryptAESError, null);
        }
    }

    /**
     * 对密文进行解密
     * @param string $encrypted 需要解密的密文
     * @return string 解密得到的明文
     */
    public function decrypt($encrypted, $appid)
    {

        try {
            $iv = substr($this->key, 0, 16);          
            $decrypted = openssl_decrypt($encrypted,'AES-256-CBC',substr($this->key, 0, 32),OPENSSL_ZERO_PADDING,$iv);   
        } catch (Exception $e) {
            return array(ErrorCode::$DecryptAESError, null);
        }
        try {
            //去除补位字符
            $pkc_encoder = new PKCS7Encoder;
            $result = $pkc_encoder->decode($decrypted);
            //去除16位随机字符串,网络字节序和AppId
            if (strlen($result) < 16)
                return "";
            $content = substr($result, 16, strlen($result));
            $len_list = unpack("N", substr($content, 0, 4));
            $xml_len = $len_list[1];
            $xml_content = substr($content, 4, $xml_len);
            $from_appid = substr($content, $xml_len + 4);

        } catch (Exception $e) {
            //print $e;
            return array(ErrorCode::$IllegalBuffer, null);
        }
        if ($from_appid != $appid)
            return array(ErrorCode::$ValidateAppidError, null);
        return array(0, $xml_content);

    }


    /**
     * 随机生成16位字符串
     * @return string 生成的字符串
     */
    function getRandomStr()
    {

        $str = "";
        $str_pol = "ABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789abcdefghijklmnopqrstuvwxyz";
        $max = strlen($str_pol) - 1;
        for ($i = 0; $i < 16; $i++) {
            $str .= $str_pol[mt_rand(0, $max)];
        }
        return $str;
    }

}

?>

博客：微信小程序与 PHP 7.1 的一点小坑 这个有用吗？

一句话搞定 ～～～

$msg = "加密字符串";
$key = "uXchiSqrsWLBekIXafSMvTFEg4FbibQxX1Sg3BiNgeu";
$key = base64_decode($key.'=');
$iv = substr($key, 0, 16);

$txt = openssl_decrypt(base64_decode($msg), 'AES-256-CBC', $key, OPENSSL_RAW_DATA, $iv);
dump($txt, ord("\x00"));

结果：93ed27977874df7e\x00\x00\x00¯{"ToUserName":"gh_4147ba16da01","FromUserName":"oPSpM4zJEVd1_BKMdY7rQqOQuLpc","CreateTime":1635155332,"MsgType":"event","Event":"user_enter_tempsession","SessionFrom":"sobot"}wxf4c4b50c44eb9b8b