Encrypt RSS feeds

I dont know if this is the right place for this kind of discussion, but I think this idea comes under webservices and I desperately need help.
The discussion here
http://groups.drupal.org/node/9719 consists of a great idea to encrypt RSS feeds of private posts. But the discussion there has been dead and not updated for quite some time.
This says that "
Overview: With Encrypted RSS/Atom feeds, buddylist-like features become possible cross-site. The project would be to develop a module which generates and consumes syndicated feeds, where reading them in only possible behind a login.

Details: With all of the social networking sites these days, decentralized ways of connecting across communities are still being developed. One thing that's impossible now is sharing private blog posts with someone outside of your group. This project touches on social networking, encryption, both of which are fascinating.

Drupal is a perfect platform for this, because of the wide use across micro-communities. With this module, two separate bloggers that use drupal should be able to share their private posts with each other without necessarily requiring a user name.

With this in place, future directions could lead to browser plugins which decrypt these feeds/microformats on a page with public keys."

I want to see whether this service has been achieved or not(in my knowledge it isnt.)
As on the discussion on the page, this module one created is very helpful but requires a great deal of work.I also need to know if this project is worth doing? So I need some guidance in doing this and I also have some doubts regarding the details that the module should contain in the project page.

Firstly it says "The project would be to develop a module which generates and consumes syndicated feeds, where reading them in only possible behind a login."
But later in the details section it says that "With this module, two separate bloggers that use drupal should be able to share their private posts with each other without necessarily requiring a user name." Why does it say initally that reading them should be possible only behind a login but sharing private posts with each other shouldnt require a username.