First, thank you for this project! One thing I misunderstood at first was, that after you configure putty by specifying in the private key section: cert://cn=MY NAME,thumbprint=12345e23b34c4e67cdf1ec586be0a2e886abc123 That you shouldn't use pageant authentication, by either: - unchecking "Attempt using pageant authentication" - removing your smartcard cert from pageant - or closing pageant As if you try with pageant authentication, you'll get a pin prompt (activclient pin prompt for me), only the first time and it will work to login, but on subsequent attempts that pin prompt doesn't appear and logins will fail. On the putty window you'll get: Server refused public-key signature despite accepting key! And in /var/log/secure you get: sshd: error: RSA_public_decrypt failed: error:0407006A:lib(4):func(112):reason(106) --- I've compared this project to other similar projects. - cygwin64\openssh64 with my activclient pkcs#11 64bit dll Issue: returned a seg fault for me - puttywincrypt: sourceforge.net/p/puttywincrypt based on putty-0.64 It's up to date and works :-) - putty-cac www.risacher.org/putty-cac/ based on putty-0.62 It's outdated. - putty-sc www.joebar.ch/puttysc/ based on putty-0.60 It's outdated. --- My next step is to figure out if I can use my smartcard for elevating with sudo command, then I could get rid of my password on all my linux servers and use only my SmartCard...