How to confirm visitor status to another site?

Question

OAuth

The task is to confirm some user action to a number of resources on another resource. Something like oAuth, but anonymous.
Let's say there is a site check.ru. On it, the user performs some action and receives a status. Now this status needs to be reported to another resource. An example would be a user's status in an instant messaging manager. You just need to be safe, secure and anonymous.
More detailed description:
The user enters check.ru and receives a randomly generated key, which he enters into the software running on the machine. In his browser cookies, we save the key id.
Further, if the user has an application running with this key, it has a permanent connection with check.ru, so check.ru always knows what status the application is in (whether it is running or not).
Those. when a user enters check.ru, we can read the cookie and see if the application works with the key corresponding to this cookie and show the user his status.
How to report this status to a third-party resource?
Reliably, securely, without registration and SMS? ;)
What are the ways? Which to choose? Perhaps there are some libraries or similar possibility in some frameworks?
PS
I hope I made it clear enough.

Answer 1

An application can keep a socket open, which can then be connected to by a script on a page that wants to check for the existence of a resource.
check.ru may not take part in the verification at all - its task is to sign the confirmation with its private key.
Then the application, having the check.ru public key, will be able to decrypt the confirmation, and then deliver this confirmation to the requesting site via the web socket.