Show DIV element if ViewBag in NULL in ASPNet MVC

I have the following code in my controller:

public async Task<IActionResult> Index()
{
    string destinationDirectory = _configuration["DestinationPath"].ToString();
    string DocHash = hd.GetUploadedDocumentHash(destinationDirectory);
    ViewBag.Message = await ap.verifyHash(DocHash);
    return View();
}

This is my View:

@model Models.basicInfo

Fill out basic details.
<div id="IDShow">
    <h4>@ViewBag.Message</h4>
</div>  
<div class="row" id="idHide">       
    <form asp-action="Edit">
        <div asp-validation-summary="ModelOnly" class="text-danger"></div>
            <div class="form-group row">
                <div class="col-md-6">
                    <label asp-for="TransactionNumber" class="control-label"></label>
                    <input asp-for="TransactionNumber" class="form-control" />
                    <span asp-validation-for="TransactionNumber" class="text-danger"></span>
                </div>
                <div class="col-md-6">
                    <label asp-for="ProcessedDate" class="control-label"></label>
                    <input asp-for="ProcessedDate" class="form-control" type="date" />
                    <span asp-validation-for="ProcessedDate" class="text-danger"></span>
                </div>
            </div>
            <div class="form-group row">
                <div class="col-md-6">
                    <label asp-for="CustNumber" class="control-label"></label>
                    <input asp-for="CustNumber" class="form-control" />
                    <span asp-validation-for="CustNumber" class="text-danger"></span>
                </div>
    </div>
</div>

if  @ViewBag.Message message has something in it then, I want to hide the "idHide" div tag and show the "IDShow" div tag and if the @ViewBag.Message is blank, then I want to show the idHide section and hide the "IDShow" tag.