IRM- Information Rights management protection can be applied to Share point List or Libraries. If its applied, you can all only permitted users can access the documents.
Information Rights Management (IRM) enables you to limit the actions that users can take on files that have been downloaded from SharePoint lists or libraries. IRM encrypts the downloaded files and limits the set of users and programs that are allowed to decrypt these files. IRM can also limit the rights of the users who are allowed to read files, so that they cannot take actions such as print copies of the files or copy text from them.
Power shell Script to activate IRM on a Sharepoint Library
$web = Get-SPWeb http://mylibrary/site
$list = $web.GetList("MyLibrary")
$list.IrmEnable = $true
$list.Update()