can Git encrypt/decrypt .gpg on push/fetch?

I need to store some encrypted files in Git but for some clients with the right GPG keys, decrypt them on checkout (possibly also encrypt them back on commit, but that's not as important).

diff doesn't have to work, this is just for convenience. Can Git do this (matching only .gpg files) or do I need my own command to run after the checkout/fetch and before commit? It seems pretty out of Git's scope but perhaps others have done this before.

Thanks Ted