Redmine

I need a better way to manage files that are released on a project. For example, I'd like to be able to control access permissions (download, list,and write) to each file, or each file on a particular version, on the three main levels, project member, non-member, anonymous. Also, some way to add additional information or notes to the file view would be awesome. Does anyone have a plugin for this? If roll my own, which model do you think i should extend?