如何在使用.netcore的代码中实现微软Bot Framework v4机器人的基于证书的身份验证？

public class CertificateAuthenticationMiddleware
{
    private readonly RequestDelegate _next;

    public CertificateAuthenticationMiddleware(RequestDelegate next)
    {
        _next = next;
    }

    public async Task InvokeAsync(HttpContext context)
    {
        if (context.Request.IsHttps && context.Connection.RemoteIpAddress != null)
        {
            X509Certificate2 clientCertificate = GetClientCertificate(context);

            if (clientCertificate == null || !IsValidCertificate(clientCertificate))
            {
                context.Response.StatusCode = StatusCodes.Status403Forbidden;
                return;
            }
        }

        await _next(context);
    }

    private X509Certificate2 GetClientCertificate(HttpContext context)
    {
        // 从请求中获取客户端证书
        // 这里需要根据实际情况实现
        return null;
    }

    private bool IsValidCertificate(X509Certificate2 certificate)
    {
        // 验证证书的有效性
        // 这里可以包括检查证书链、有效期等
        return true;
    }
}