This project allows you to use various hardware security devices to operate GPG and SSH. Instead of keeping your key on your computer and decrypting it with a passphrase when you want to use it, the key is generated and stored on the device and never reaches your computer. Read more about the design on
https://github.com/romanz/trezor-agent/blob/master/doc/DESIGN.md
Currently TREZOR One, TREZOR Model T, Keepkey, Ledger Nano S, and OnlyKey are supported.