slackbuilds/system/password-store

password-store is a simple password manager which uses GnuPG to 
securely encrypt and retrieve passwords.

By default, bash completion is installed as 
/etc/bash_completion.d/password-store. Add 'source 
/etc/bash_completion.d/password-store' to your .bashrc to enable it.

zsh and fish completion is also optionally included.
uncomment the lines in the SlackBuild to include it in the package.