Cryptkeeper in Mint 17 and 18 / Ubuntu 14.04 and 16.04 is buggy, so the solution is to install workable precise version.
sudo apt-get purge cryptkeeper
After purging download and install using Gdebi the precise version about Cryptkeeper.
Edit: Those links seem to be vanished, but the right packages can be found from https://pkgs.org/download/cryptkeeper
After installing, freeze the version.
sudo apt-mark hold cryptkeeper