There is a corporate web mail site (PHP + MySQL) for limited numbers of users who are employees of a company working remotely with the corporate web portal. Each user has a login and password.
I'm thinking about replacing usual text passwords with a key file, i.e. user choose any file to be the key at his first logon, it can be a text file or even a picture, the checksum of that file gets stored in the database and at next time such a user needs to loging he uploads his key file instead of typing a password. Would such authentication be more secure than a password typing? I guess it is much harder to figure out a key file than a password.