Set up SSH public key authentication

This guide contains description of setting up public key authentication for use with WinSCP. You may want to learn more about public key authentication or SSH keys instead.

Before Starting
Generate Key Pair
Configure Server to Accept Public Key
Configure WinSCP Session
Further Reading

Before Starting

Before starting you should:

Generate Key Pair

If you do not have a key pair yet, start with generating new key pair.

Configure Server to Accept Public Key

Connect to your SSH server using WinSCP with the SSH protocol, using other means of authentication than public key, e.g. typically using password authentication.

Once logged in, configure your server to accept your public key. That varies with SSH server software being used. The most common SSH server is OpenSSH.

OpenSSH

Navigate into a .ssh subdirectory of your account home directory. You may need to enable showing hidden files to see the directory. If the directory does not exists, you need to create it first.
Once there, open a file authorized_keys for editing. Again you may have to create this file, if this is your first key.
Switch to the PuTTYgen window, select all of the text in the Public key for pasting into authorized_keys file box, and copy it to the clipboard (Ctrl+C). Then, switch back to the editor and insert the data into the open file, making sure it ends up all on one line. Save the file.
Ensure that your account home directory, your .ssh directory and file authorized_keys are not group-writable or world-writable. Recommended permissions for .ssh directory are 700. Recommended permissions for authorized_keys files are 600. Read more about changing permissions.

ssh.com

Save a public key file from PuTTYgen, and copy that into the .ssh2 subdirectory of your account home directory.
In the same subdirectory, edit (or create) a file called authorization. In this file you should put a line like Key mykey.pub, with mykey.pub replaced by the name of your key file.