Just so it&#x27;s clear, the previous Yubikey NEO also supports gpg-agent for SSH authentication, not just the new Yubikey 4. I&#x27;ve been using one for months. It presents a standard smarcard CCID interface and runs an OpenPGP applet.<p>The source to the actual Javacard applet that implements is available on Github: <a href="https:&#x2F;&#x2F;github.com&#x2F;Yubico&#x2F;ykneo-openpgp" rel="nofollow">https:&#x2F;&#x2F;github.com&#x2F;Yubico&#x2F;ykneo-openpgp</a>