📄gpg-agent.conf

GPG config file used to manage the agent daemon. Edits are required to make Yubikey and SSH / PuTTY work together.

gpg-agent is a daemon to manage secret (private) keys independently from any protocol. It is used as a backend for gpg and gpgsm as well as for a couple of other utilities.

The agent is automatically started on demand by gpg, gpgsm, gpgconf, or gpg-connect-agent. Thus there is no reason to start it manually.

Absolute Path:

C:\Users\user\AppData\Roaming\gnupg\gpg-agent.conf

Run String:

%AppData%\gnupg\gpg-agent.conf

Modify config to enable Yubikey + PuTTY / SSH:

gnupg\gpg-agent.conf

enable-putty-support
enable-ssh-support
use-standard-socket
default-cache-ttl-ssh 60
max-cache-ttl-ssh 120
default-cache-ttl 60
max-cache-ttl 120
pinentry-program "C:\Program Files (x86)\Gpg4win\bin\pinentry.exe"

You must add the above code so that you can enable SSH and Putty support. Once the changes have been made; restart the gpg-agent:

gpg-connect-agent killagent /bye
gpg-connect-agent /bye