Forwarding your GPG agent over SSH

If you keep your GPG keys on a smartcard (like a Yubikey as I do), you can use them on a remote host over SSH without ever copying a private key off the card. The signing and decryption happen on your local computer, driven by the remote; and the keys never leave the hardware. This is GPG agent forwarding, and it’s very useful for signing commits or decrypting files on a remote computer.