Download ability with Authentication and Resume support in ASP .NET (C#)

We have a web application that provides Files to be downloaded by users of our own site. Since some of users prefer to download files with Resume ability (like to be accelarated by download managers), We need to authorize the user and send the contents of file through http responses. We need a simple complete code for our HTTP Handler page written in ASP C# .NET 2005 which handles all http requests and sends requested parts of files after authorizing users. Assume that we check a user's permission to download a file by calling this function: bool CheckPermission(string Username, string Password, int FileID) Note that we link to a download by calling the HTTP Handler page having the file ID as its query string (such as [login to view URL]). By receiving a download request, an authentication request should be sent to the user, and once a username/password is receiving, the permission should be checked by the function and in case of authentication, the requested parts of the file should be read form local disk and be sent to the user. This should support download resuming/accelaration. The local loaction of a file can be gotten by giving its ID to a function. Please bid if you can handle this job without any problem and Feel free to ask any questions. Payment after delivery and satisfication.