From the server console, click Configuration > Authentication > Public Key.
Use the Public Key pane to configure user authentication using public keys.
The options are:
Public key authentication
Allow
Public keys can be used for client authentication, but are not required.
Require
Clients must present a valid public key to connect.
Deny
Clients must use some other authentication method besides Public Key to connect.
Public key storage
User key directory
Specifies the directory used for storing user public keys on the server. You can use any of the following pattern strings to specify user-specific directories. For details see Pattern Strings in Directory Paths.
The user profile folder is configurable by the Windows system administrator. The default is:
Windows XP: C:\Documents and Settings\<user>\ Windows Vista: C:\Users\<user>\
%u
The user's login name.
%U
The user's domain name and login in the format domain.username.
Authorization file name
The name of the file in the user key directory that contains a list of public keys that can be used for user authentication. The default name is authorization.
Size
Public key minimum length (bits)
Specifies the minimum allowable key size. The default is 512. Allowed values are 512-8192.
Public key maximum length (bits)
Specifies the maximum allowable key size. The default is 8192. Allowed values are 512-8192.