Using the most recent version 2.2.1 of Gpg4win, the GnupPG distribution for windows, you are able to use your GPG-keys for ssh-authentication.
In this post, I will show how to setup your environment to do exactly that: use your gpg-keys for ssh-authentication with putty.
In this post, I show how you set up your shell environment on a Mac to allow SSH authentication with a GPG key.
This solutions works for multiple shell-instances, even if you close them occasionally or if your Mac went to sleep.
What you need: