I would like to restrict the visibility for one of my custom aspects in alfresco 5.0.d depending on the groups or particular users. I know how to create the aspect but I've never work on the configuration of permissions and I have no idea how to do that. I searched it a month ago, I suppose I can modify the permissionDefinitions.xml but I have no idea how it works.
I don't think you will get this out of the box. Permissions are at node level rather than property or aspect level.
There may perhaps be some RM capability that I don't know about. Or you may be able to do something with your user interface, but that's not really security.