微信消息加解密Mcrypt在php7.2中废弃与open_ssl替代解决方案

<?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 {            //获得16位随机字符串，填充到明文之前            $random = $this->getRandomStr();            $text = $random . pack("N", strlen($text)) . $text . $appid;
            $iv = substr($this->key, 0, 16);            //使用自定义的填充方式对明文进行补位填充            $pkc_encoder = new PKCS7Encoder;            $text = $pkc_encoder->encode($text);            $encrypted = openssl_encrypt($text, 'AES-256-CBC', $this->key, OPENSSL_RAW_DATA, $iv);            return array(ErrorCode::$OK, base64_encode($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);            //使用BASE64对需要解密的字符串进行解码            $decrypted = openssl_decrypt(base64_decode($encrypted), 'AES-256-CBC', $this->key, OPENSSL_RAW_DATA, $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;    }
}
?>