I have done a google search for "multi-party key agreement", and there doesn't seem to be anything more recent than about 2005.
Are there any practical multi-party key agreement protocols known?
To be more precise, I want a protocol which:
- Allows multiple individuals to agree a single shared secret
- An adversary cannot tell what the shared secret is by listening to the communications.
- It should be authenticated so an active adversary cannot persuade a participant to communicate with a secret the adversary knows.
Note: I am aware of Multi-party Key Exchange protocol from lattice but a) that doesn't have any answers; b) I am not only interested in lattice cryptography (in fact, I would prefer something based on ECC or factoring).
Edit: Background I want a system for encrypting a conference call. If each caller sends their audio to every other participant with separately agreed keys, then the total amount of work required is $O(n^2)$ (and the work done by each participant is $O(n)$). If everyone agrees a single shared secret, then we might be able to reduce the amount of work required.