Yes, you can sign your commits! GIT supports it out of the box.
Check your keys
Add your fingerprint to your git configuration
$ git config --global user.signingkey A37721C3
Now you can sign your commits!
$ git commit -a -S -m 'fixed bugs, added new'
Here you can read full git documentation about this great feature.
Fortune cookie: We have no scorched earth policy. We have a policy of scorched Communists. -- General Efrain Rios Montt, President of Guatemala, 1982