[Cryptography] IPFS: what's PKI got to do with it?

[Henry Baker]

I've read the papers on IPFS, and understand that
somehow a *mutable* binding gets 'published' to the
cloud, and has to be refreshed every 24 hours or so.

But what I can't determine from the papers is where
public key encryption fits in.

Somehow, a PKE pair is involved in *mutable* bindings,
but none of the papers seem to describe this process
in an intelligible way.

I understand fully well how the *immutable* bindings
work; I'm only interested in understanding how the
*mutable* bindings work.

I.e., I fully understand "ipfs://"; what I can't
figure out is "ipns://" and friends.

Thx in advance for any pointers.