A convenient way for passwords is to keep inputting digits in sequence and at each digit being input to look at the last "N" entries to see it they match the stored password. Make the stored password variable length and the ONLY way it wakes up is if the correct sequence is given. It is also nice becasue the user is never shown a prompt that something she/he entered is incorrect. If they do enter something wrong and they know it then all they have to do is start over with the correct sequence. This scheme is as secure as the known universe of input digits and the actual password string length. The scheme encourages the use of longer strings as opposed to shorter strings for obvious reasons. It may seem a bit more secure to have the user enter a string of digits and then hit an <enter> type key. However this is really no different than the scheme I suggested with the <enter> key code happening to be the last character of the password string.

Have Fun
Michael Karas