Colin WaltersA while ago, I started a discussion on stronger verification of git tags:
http://permalink.gmane.org/gmane.comp.version-control.git/264533
Since then I've been maintaining: https://github.com/cgwalters/git-evtag
Which I think works well. At some point I'd like to discuss merging some of the functionality into the git core.
However it's been useful to have a standalone program so that I don't have to wait until a new version of git comes out, and it's also just easier to prototype.
For those interested, a new version of git-evtag is available:
https://github.com/cgwalters/git-evtag/releases/tag/v2016.1