No need for homebrew or anything like that. Works with https://www.git-tower.com and the command line.
- Install https://gpgtools.org -- I'd suggest to do a customized install and deselect GPGMail.
- Create or import a key -- see below for https://keybase.io
gpg --list-secret-keysand look for
sec, use the key ID for the next step
gitto use GPG -- replace the key with the one from