Codes and passwords are often found: * on pocket secretaries on guards or in hidden areas, * in e-mails on computers, * from some conversations (the CASIE aug helps). If you have the keycode for a particular lock it will be displayed on-screen and you can simply input the digits and bypass the hacking process (but this denies you the XP gain you'd get from the hack). Note that you do not have to discover the code in-game to be able to use it, hence this list.