Incredibly simple redirection to equivalent SSL-secured URI. This is intended to be configured on a dedicated site listening on port 80, and will blindly redirect all GET requests to the same URL with the `https` protocol, and `403.4 SSL Required` everything else.

SslRedirectionHttpHandler.cs

using System;
using System.Web;

namespace SslRedirection {
  public class SslRedirectionHttpHandler : IHttpHandler {
		public bool IsReusable { get { return true; } }

		public void ProcessRequest(HttpContext context) {
			if ("GET".Equals(context.Request.HttpMethod, StringComparison.Ordinal)) {
				context.Response.StatusCode = 301;
				context.Response.RedirectLocation = "https://" + context.Request.Url.Host + context.Request.RawUrl;
			} else {
				context.Response.StatusCode = 403;
				context.Response.SubStatusCode = 4;
			}
			context.Response.Flush();
			context.Response.Close();
		}
	}
}

web.config

<?xml version="1.0" encoding="utf-8" ?>
<configuration>
	<system.webServer>
		<handlers>
			<clear />
			<add name="SslRedirectHandler" type="SslRedirection.SslRedirectionHttpHandler, SslRedirection" path="*" verb="*" resourceType="Unspecified" preCondition="integratedMode" />
		</handlers>
	</system.webServer>
</configuration>