We use Ansible to deploy/manage peoples' SSH keys on our servers. From their laptop or a jumpbox (within the management VLAN) with their personal key (and a passphrase!) they are able to login in to all those servers. So logins are personal (as opposed to shared accounts which have to be updated when people leave). Now when new people arrive or when people leave we just run an Ansible playbook and all our 400+ server…
Do you use Ansible for SSL as well? How do you store the keys?
https://gist.github.com/tristanfisher/e5a306144a637dc739e7
Having a partly encrypted YAML file is also available since version 2.3.0
Key management and deployment are two different things. Installing up people's private keys on the hosts, doesn't involve any management. It's a standard sysadmin procedure.
Key managements involves policies such as: key rotation, algorithms to use, access restriction control, etc. It is way more daunting and complex. I don't see how ansible what ansible has to do with this, vaultproject on the other hand has most of the these features (and more) build-in. Never used it, but I know about it through a podcast presentation of vault in "Arrested Devops" IIRC.