title: Visual Studio Code: Missing X509Certificate2UI
body: <p>I get the following error when trying to use an X509Certificate2UI in VS Code:</p>
  
  <pre><code>The type or namespace name 'X509Certificate2UI' does not exist in the namespace 'System.Security.Cryptography.X509Certificates' (are you missing an assembly reference?) [netcoreapp1.1]
  </code></pre>
  
  <p>I've found a <a href="https://stackoverflow.com/questions/15617409/name-x509certificate2ui-does-not-exist-in-the-current-context/">few sites</a> that indicate the solution is to add the system.security.dll assembly, but these responses don't seem to be catered toward VS Code. I've already added the X509Certificates dependency to the project.json file, which doesn't seem to do me much good:</p>
  
  <pre><code> },
    "dependencies": {},
    "frameworks": {
      "netcoreapp1.1": {
        "dependencies": {
          "Microsoft.NETCore.App": {
            "type": "platform",
            "version": "1.1.0"
          },
          "System.Security.Cryptography.X509Certificates": "4.3.0" //"4.3.0-*"
        },
        "imports": "dnxcore50"
      }
  </code></pre>
  
  <p>Any help would be greatly appreciated :)</p>
  
  <p>-Nate</p>