c# 中调用c++ dll文件 使用VKeyGenResultExOpt函数获取KEY

using System;
using System.Collections.Generic;
using System.Linq;
using System.Runtime.InteropServices;
using System.Text;
using System.Threading.Tasks;

namespace ConsoleApp3
{
    internal class Program
    {
        enum VKeyGenResultExOpt
        {
            KGREO_Ok = 0,
            KGREO_BufferToSmall = 1,
            KGREO_SecurityLevelInvalid = 2,
            KGREO_VariantInvalid = 3,
            KGREO_UnspecifiedError = 4
        };
        [DllImport("LHM_Vector.dll", EntryPoint = "GenerateKeyExOpt" ,CallingConvention = CallingConvention.Cdecl)]//导入安全算法dll
        private static extern VKeyGenResultExOpt GenerateKeyExOpt( byte[] ipSeedArray, uint iSeedArraySize,
   uint iSecurityLevel, ref string ipVariant, ref string ipOptions,
   out IntPtr iopKeyArray, uint iMaxKeyArraySize,
   ref uint oActualKeyArraySize);//引用算法中定义的函数

        /// <summary>
        /// IntPtr转byte[]数组
        /// </summary>
        /// <param name="obj">Inptr</param>
        /// <returns></returns>
        static byte[] Intptr2byte(object obj)
        {
            int size = Marshal.SizeOf(obj);
            IntPtr intPtr = Marshal.AllocHGlobal(size);
            try
            {
                Marshal.StructureToPtr(obj, intPtr, false);
                byte[] by = new byte[size];
                Marshal.Copy(intPtr, by, 0, by.Length);
                return by;
            }
            catch (Exception ex)
            {
                Marshal.FreeHGlobal(intPtr);
            }
            return null;
        }
        static void Main(string[] args)
        {
            byte[] ipSeedArray=new byte[4] { 0X91,0X7C,0x39,0X1F}; //ECU处获取一个种子
            uint iSeedArraySize=4;//设置种子长度
            uint iSecurityLevel=7;//设置安全等级
            string ipVariant = "";//默认为空
            string ipOptions = "";//默认为空
            IntPtr iopKeyArray; //经过安全认证返回的Key
            uint oActualKeyArraySize = 0; ;//返回Key的长度



            GenerateKeyExOpt(ipSeedArray, iSeedArraySize, iSecurityLevel, ref ipVariant, ref ipOptions, out iopKeyArray, 4, ref oActualKeyArraySize);//根据种子计算Key,安全等级

           byte[] key= Intptr2byte(iopKeyArray);//得到的Key转成数组形式

            Console.WriteLine();
            Console.ReadLine();
        }
    }
}