Mint: No SSH key-based login with encrypted home directory
The problem
We had a PC running Ubuntu 14.04 (with encrypted home folders), and OpenSSH. We use key-based authentication on all our servers, and so we duly copied our public SSH key into ~/.ssh/authorized_keys. However, the computer seemed to ignore this key! Whenever we tried to SSH into the PC, we would be forced to enter a password.
After a bit of troubleshooting we realised that, if an SSH session was already established and the user opened a second session, the key-based authentication worked just fine!