Why do I need friends in cpVault ?
Friends are tightly coupled with Sharing.
In order to share a cpCard you have to add somebody to your friends list.
To do it just click on 'add friend' button and provide an email. The same one that is assigned to your friends account. He or she will receive an invitation from you and after accepting it you both have Friends status and can share cpCard with each other.
Who needs friends anyway ?
You can revoke a friend status at any moment.