src/thinkextend/Crypt.php
protected static function createIV($size)
    {
        if (function_exists('openssl_random_pseudo_bytes')) {
            $bytes = openssl_random_pseudo_bytes($size, $strong);
        }
        if (is_null($bytes) || $bytes === false || $strong === false) {
            $size *= 2;
            $pool  = '0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZ';
            $bytes = pack('H*', substr(str_shuffle(str_repeat($pool, $size)), 0, $size));
        }
        return $bytes;
    }
protected static function createIV($size)
    {
        if (function_exists('openssl_random_pseudo_bytes')) {
            $bytes = openssl_random_pseudo_bytes($size, $strong);
        }
        if (is_null($bytes) || $bytes === false || $strong === false) {
            $size *= 2;
            $pool  = '0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZ';
            $bytes = pack('H*', substr(str_shuffle(str_repeat($pool, $size)), 0, $size));
        }
        return $bytes;
    }
随机生成指定长度的初始化向量

@param  int $size 初始化向量长度

@return string