title: B2C - pass parameter in url from .net5 application
body: <p>I am calling a b2c custom policy from my .net5 application. The code I'm using to redirect users from the application to the custom policy screen is:</p>
  <pre><code>var scheme = OpenIdConnectDefaults.AuthenticationScheme;
  var properties = new AuthenticationProperties { RedirectUri = redirectUrl };
  properties.Items[&quot;policy&quot;] = &quot;B2C_1A_xxxxxx;
  
  return Challenge(properties, scheme);
  </code></pre>
  <p>I also want to pass a value across from my application to pre-populate an input on the B2C screen.</p>
  <p>I am able to get a value from a url parameter by using <code>OAUTH-KV:KeyValueKey</code> in the custom policy. Such that when I add <code>&amp;KeyValueKey=KeyValueValue</code> to the url manually, I am able to display <code>KeyValueValue</code> in the relevant input.</p>
  <p>However, am unable to update the C# code I have in the application so that I can generate the url with the parameter value included in it.</p>