Puttygen import openssl key

This morning, I wanted to do the same with Putty in Windows XP, so I just copied the private key to Windows and loaded it in Putty, but it failed: Unable to use key file "F:\Downloads\cnxsoft\a1000\id_rsa" (OpenSSH SSH-2 private key)

Unable to use key file "F:\Downloads\cnxsoft\a1000\id_rsa" (OpenSSH SSH-2 private key)

After a few minutes of research, I found my answer on UbuntuForums, and the reason it fails is because Putty does not support openssh keys, but uses its own format.Here’s what I had to do:
  1. Convert OpenSSH private key to Putty private key with Putty Key Generator (puttygen)
    Start puttygen, and click on Conversions->Import key, then click Browse and select the private key generated with openssh (e.g. id_rsa).
    Then click on Save private key (e.g. id_rsa_putty.ppk)
  2. Putty SSH login with private key.
    Now you can start Putty, enter the machine IP address or url as usual, then go to Connection->SSH->Auth.
    Click Browse, and select your private key file (e.g. id_rsa_putty.ppk), go back to Session and save the session. You should now be able to login to the server.

Puttygen import pem

Puttygen import public key

Puttygen export openssh key

Puttygen export private key

Puttygen import private key