Docker – How to prevent attach or exec in a docker container

How do a prevent a user of my pre-built docker container from being able to access a shell within a running instance of that container? I have googled and read all the posts that are related to this scenario and have come up without a working solution. I am trying to prevent access to a given resource in the container, for the sake of this inquiry, let's say its a serial number in a configuration file. I am building upon the java:7 image which is based upon an ubuntu image.

To test your solution, do the following:

1. Create and run your docker container

2. Export your container

   docker export [container name] | gzip -c > mycontainer.tar.gz

3. Import your container on an external system

   gzip -dc mycontainer.tar.gz | docker import – [container name]

4. Run the container

5. Shell into the running container using any / all of the following methods:

   docker exec -it [container name] bash

   docker attach [container name]

   docker run -ti –entrypoint=/bin/bash [container name]

[container name] is the name of your container

bash, dash, and sh are all valid shells