1. Launch PuTTY Key Generator (puttygen.exe)

launch putty key generator

2. Click on the FileLoad private key and select your PuTTY’s key file, which normally ends with .ppk extension.

load private key putty

3. Enter the key’s passphrase if prompted.

4. Detail of the imported key will be displayed.

details of imported key putty

5. Go to ConversionsExport OpenSSH key from the menu.

export OpenSSH key

6. Save your converted key to a new file and location.

save putty key