Let's take the case on MeaningOfIdentity for a moment. Since the network is inheritantly unsecure, any errant machine may masquerade as another.
There are a few cases to consider.
Instead of identifying itself explicitly, a machine consistently uses an alias. For instance, a machine that outputs statistics on human rights violations in its country wishes to build a reputation for itself without identifying its location or who owns it.
Theft of identity
Using another computer's identity on the network and masquerading as it.
Resurrection of dead identity
Using an identity that was used years ago by another computer that had been taken offline. This happens a lot on the internet as practical jokes, actually.
If one machines correct some other machine's posting, that first machine adds content to the other's IdentityContext?.
Denial of identity
One machine denies ownership of data that it created.
What are the effects of subverting an identity to both the subverter and subvertee?
Why do it?
What can you do to get around the ethically wrong subversions without discouraging the ethically right subversions?
This is a hard computer security problem.