Get secure file download ticket via .NET API

Using the Microsoft.TeamFoundation .NET client APIs, how can I get a download ticket for a secure file from TFS 2017u2?

Using the Microsoft.TeamFoundation.DistributedTasks.WebApi nuget package, I puffed up the below code in a console app. It successfully retrieves all the metadata and associated properties entered in TFS for the secure file. However, despite passing the "includeDownloadTicket" argument as "true" to the GetSecureFileAsync method, the Ticket property is always null.

I thought perhaps it was a permissions issue but I am in the TFS Admin role and also specifically assigned myself as an admin to the file entry in the web interface.

var credentials = new VssCredentials();
var projectName = "{myProjectName}";
var secureFileId = new Guid("{theSecureFileId}");
var tfsUri = new Uri("https://{tfsBox}/{collection}");
var connection = new VssConnection(tfsUri, credentials);
var taskAgentClient = connection.GetClient<TaskAgentHttpClient>();
var projectClient = connection.GetClient<ProjectHttpClient>();
var project = await projectClient.GetProject(projectName, true);
var secureFile = await taskAgentClient.GetSecureFileAsync(project.Id, secureFileId, true);
var secureFileTicket = secureFile.Ticket;

if (secureFileTicket == null)
{
    Console.WriteLine(
        "No download ticket was provided by the TFS for the requested Secure File.");
    return;
}

Your thought is right. This is related to the permission. For security reason, normal users are limited to download the secure files. The permission you can set is "Reader", "User" and "Administrator" for normal users while it requires "ViewSecrets" permission to include the download ticket.

So you cannot download the secure files for now.