user access to private directory

How to set permission to allow User1 the write access to download a file(person) to rooted directory (/bucket) but is not allowed to do nothing else to the directory except download file (person), user2 needs read access to file(person)in rooted directory (/bucket) and import file (person)into user2 server

How do I set the permission on rooted directory(/bucket) and user permission for the above users