use post id as url shortner

Hi,

I would like to post my posts to twitter automatically using the mydomain.com/post_id as the shortened form.

I am looking around at information on this but getting confused. It’s more the url shortening that I am worried about than the sharing to twitter.

Is there a plugin in or something that can extract the post id and make a short url out of it? And does it mean I have to change my permanlink structure?

Thanks!