Make possible to cipher keys in the ~/.juju/environments.yaml file

I'd like to be able to cipher the pass keys details in the ~/.juju/environment.yaml file, so I can put all my details there, upload it to the Internet and be sure nobody can use my ec2 account, something like this:

environments:
  sample:
    type: ec2
    access-key: $(cat access-key) //or hash function here
    secret-key: $(cat secret-key)
    control-bucket: juju-8b53699f85c0438c96897ce75f633aa1
    admin-secret: 9a7c512f938f4bafb96365d7ceaf569b
    default-series: precise
    ssl-hostname-verification: true

Or through hash functions, whenever you feel is easier to develop