US Government systems typically use client certificates as a component of access...

		zrail on March 28, 2015 \| parent \| context \| favorite \| on: Slack was hacked US Government systems typically use client certificates as a component of access control in the form of the Common Access Card[1]. Not that that's a business, or even a success from the point of view of the users, but it's one of the largest deployments of client side certs out there. [1]: http://en.m.wikipedia.org/wiki/Common_Access_Card

Unfortunately the only reason they can do that is that they are the government.