[messaging] IBE for Service Sub-Keys?

[Tom Ritter]

So I'm not claiming to have studied IBE in depth, but....

While thinking about PGP and subkeys today, I started wondering about
an IBE-like or BIP-32-like system, where if you have a public key, you
can generate a new public key for a 'tag', and given a private key and
a tag you can generate the tag's private key.

This would let you publish a master key (like in PGP) and then people
who want to communicate with you over, say, 'OTR' or 'ZRTP' can
generate a service subkey for you automatically, and you can generate
the corresponding private service subkey, even after they've generated
a public key.

You'd have to do an ugly dance about revoked service keys, like
publish a linked list with your master key 'OTR' -> 'OTR_2'.

-tom

PS: This was also in no way influenced by my
subkey-expiration-without-noticing a week ago ;)