Ask HN: Do any file storage sites offer start/end time restricted access?

I have a business need for allowing a user to upload a file to a central location, with the uploading user placing a time restriction on when the file can be seen and downloaded by other users. The time restriction has to include a start and end date and time. Does anyone know if something like this can be accomplished with Dropbox? Or other sites?

The users are not all technically savvy so a solution that offered a web based front-end is preferred. Or a solution that provided an API that I could put a front-end in front of would work.