var pathRoute = routes.MapRoute("Path", "{*path}",
                defaults: new { controller = "Entries", action = "Index", path = "index" },
                constraints: new { path = new EntryRouteConstraint() },
                namespaces: DefaultNamespaces);

            pathRoute.RouteHandler = new EntryRouteHandler();

            var pathRoute = routes.MapRoute("Path", "{*path}",
                defaults: new { controller = "Home", action = "Default", path = "index" },
                constraints: new { path = new EntryRouteConstraint() },
                namespaces: DefaultNamespaces);

            pathRoute.RouteHandler = new EntryRouteHandler();

    public class EntryRouteConstraint : IRouteConstraint
    {
        public bool Match(HttpContextBase httpContext, Route route, string parameterName, RouteValueDictionary values,
                          RouteDirection routeDirection)
        {
            if (routeDirection == RouteDirection.UrlGeneration)
            {
                return true;
            }
            var path = values[parameterName] as string;
            if (path == null)
                return false;
            var resolved = EntryManager.Current.Resolve(path);
            if (resolved == null)
                return false;
            httpContext.Items["EntryMap"] = resolved;
            return true;
        }
    }

    public class EntryRouteHandler : MvcRouteHandler
    {
        protected override IHttpHandler GetHttpHandler(RequestContext requestContext)
        {
            var entryData = requestContext.HttpContext.Items["EntryMap"] as EntryData;
            var routeData = requestContext.RouteData;
            // разруливаем обработчик (контроллер/экшен)
            ResolveRouteData(entryData, routeData);
            // сохраняем ID (можно и в RouteData.Values, но лучше не надо)
            routeData.DataTokens["entryId"] = current.Id;
            return base.GetHttpHandler(requestContext);
        }

        private static void ResolveRouteData(EntryData entryDate, RouteData routeData)
        {
           switch(entryData.ResourceType)
           {
               case ResourceTypes.Redirect:
                  routeData.Values["controller"] = "Entries";
                  routeData.Values["action"] = "Redirect";
                  break;                  
               case ResourceTypes.Article:
                  routeData.Values["controller"] = "Articles";
                  routeData.Values["action"] = "Details";
                  break;
               ...                 
           }
        }
    }

    public class EntryManager : IEntryManager
    {
       ...
       public EntryData Resolve(string path)
       {
          using(var sha1 = SHA1.Create())
          {
             // считаем хеш
             var hash = sha1.ComputeHash(Encoding.UTF8.GetBytes(path.ToLower());
             // ключ хеша
             var hashKey = new Guid(hash);
             EntryData entryData;
             // ищем ресурс в таблице (упрощённо)
             if(_entryTable.TryGetValue(hashKey, out entryData))
               return entryData;
             // ресурс не найден
             return null;
          }
       }
       ...
    }

    public ArticlesController : Controller
    {
        public ArticlesController(Lazy<IArticleService> service)
        {
            _service = service;
        }
        
        private IArticleService Service { get { return _service.Value; } }

        ...
        public ActionResult Details()
        {
           // достаём значение ID ресурса (можно и лучше это сделать в аспекте)
           var entryId = (int)ControllerContext.RouteData.DataTokens["entryId"];
           // получаем ресурс
           var article = Service.GetArticle(entryId);
           ... 
        }
        ...
    }

    // минимум информации о ресурсе -- тип и ID, можно оформить в виде struct для экономии
    public class EntryData
    {
       public int Id { get; set; }
       public ResourceTypes ResourceType { get; set; }
    }