Linking (un)loading of your SSH private keys with your screensaver state

gistfile1.py

import dbus.mainloop.glib                                                                                                                                                           
import gobject                                                                                                                                                                      
from subprocess import Popen                                                                                                                                                        
dbus.mainloop.glib.DBusGMainLoop(set_as_default=True)                                                                                                                               
                                                                                                                                                                                    
def screensaver_state_changed(new_state):                                                                                                                                           
    if new_state:                                                                                                                                                                   
        # screen saver changed state to "active"                                                                                                                                    
        Popen(["/usr/bin/keychain", "--clear"]).communicate()                                                                                                                       
    else:                                                                                                                                                                           
        # screen saver changed state to "inactive"                                                                                                                                  
        Popen(["/usr/bin/keychain", "/path/to/private/key"]).communicate()                                                                                             
                                                                                                                                                                                    
BUS = dbus.SessionBus()                                                                                                                                                             
                                                                                                                                                                                    
PROXY = BUS.get_object(                                                                                                                                                             
        'org.kde.screensaver',                                                                                                                                                      
        '/ScreenSaver'                                                                                                                                                              
        )                                                                                                                                                                           
                                                                                                                                                                                    
PROXY.connect_to_signal(                                                                                                                                                            
        'ActiveChanged',                                                                                                                                                            
        screensaver_state_changed,                                                                                                                                                  
        dbus_interface = 'org.freedesktop.ScreenSaver')                                                                                                                             
                                                                                                                                                                                    
loop = gobject.MainLoop()                                                                                                                                                           
loop.run()