Public Key User Authentication.

For public key user authentication, a pair of user keys must be created comprised of a public key and a private key. While public key authentication is carried out, the private key is used by Xshell to create a user signature and the public key is used by the SSH server to check the signature.
A user key may be created from the SSH server or Xshell. If the user key is created from the server, the private key must be registered in the Xshell private key repository using Xshell import. If the user key is created from Xshell, the public key must be registered in the server.
To Create a User Key:

1. Select [New User Key Wizard] from the [Tools] menu.
2. Create a user key according to instructions given by the New User Key Wizard.

• Note 
  Register a public key on a server at the last stage of key creation. Registration methods vary depending on server types. 
  • SSH1: Copy the public key text and save it to $HOME/.SSH/authorized_keys file. Execute the following command to turn off the write permission of the files and directories.
    $ cd
    $ chmod go-w . .SSH .SSH/authorized_keys
  • SSH2-OpenSSH: OpenSSH servers use this format. Copy the public key text and save it to $HOME/.SSH/authorized_keys2 file. Execute the following command to turn off the write permission of the files and directories.
    $ cd
    $ chmod go-w . .SSH .SSH/authorized_keys2
  • SSH2-IETF SECSH: Certain commercial SSH servers, such as ssh.com server, use this format. Save a public key under an intrinsic name, such as mypublickey.pub and copy it to $HOME/.ssh2 directory. Add the following line to $HOME/.ssh2/authorization file:
    Key mypublickey.pub
    Execute the following command to turn off the write permission of the files and directories.
    $ cd
    $ chmod go-w . .ssh2$ chmod go-w .ssh2/authorization .ssh2/mypublickey.pub

To Register a Public Key in a Server:

1. Open the User Keys dialog box by selecting [User Key Manager] from the [Tools] menu.
2. Select a user key to register.
3. Click [Properties]. The User Key Properties dialog box is displayed.
4. Click the [Public Key] tab.
5. Select an appropriate type from the [Public Key Format] list.
6. Click [Save as a file] to save or copy the key content and register the key to the server according to the public key registration method above.

To Change the User KeyPassphrase:

1. Open the User Keys dialog box.
2. Select a user key for which to change the passphrase.
3. Click [Properties]. The User Key Properties dialog box is displayed.
4. Click the [General] tab.
5. Click [Change Passphrase].

• Note
  Import, export, rename, delete, and create a user key in the 'User Keys Dialog Box'.