WordPress - generate random id each time a post is loaded

CONTEXT

I have an index page that displays a list of posts. In addition to having each post identified by a unique ID, I would like each viewing session of a post (i.e. a specific user views a specific post at a specific time) to be unique.

PROBLEM

Is there an easy way to generate a unique ID that identifies the current single-post viewing session, on post load?

via Chebli Mohamed