A mechanism is provided for protecting a plurality of electronic files. A portable access control lock is adapted for automatically maintaining an audit trail and allowing for configuring of access control rules for constraining user access based on a mandatory presence of specified users before granting access for each electronic file including any copies of the each electronic file of the plurality of electronic files. The constraining user access based on the mandatory presence of specified users comprises specifying persons P1 and P2 both of whose presence are required in order to update or view any of the each electronic file including the copies of the each electronic file. Persons P1 and P2 are prompted by a same access agent on a same access computer for authentication credentials to access the each electronic file and the each electronic file is accessed only when persons P1 and P2 are properly authenticated.