ABSTRACT
When we login (sometimes called signing in), to a computer, we must provide a passphrase, which may be as simple as a single word (typically called a password), or a sequence of words used to identify us uniquely for secure access to the system. The encrypted passphrase will be accompanied by our plaintext username ID. A user ID, authenticated by its associated passphrase, determines the privileges allotted to the user, which may vary from personal e-mail access to superuser status, where actions may be executed that are protected by the operating system.
