Yes, you have correctly understood what I want to achieve (and did achieve with v1). The envelope can be checked, and actually gives us mutual trust, as I need not “blindly” trust my friend. We both, mutually, know he can not have peeked into the files (and vice versa for what he has deposited and trusts me with).
I do the same on occasions when I deposit a house key with my neighbours. It is handed over in a sealed package. Should any situation warrant entry they can break the package, and if not (which is of course the norm) I get it back intact, knowing that they have not entered, and they need not wonder if I am suspicious of them.