In telecommunication, a password length parameter is a basic parameter affecting the password length needed to provide a given degree of security.

Password length parameters are related by the expression P = L*R /S , where P is the probability that a password can be guessed in its lifetime, L is the maximum lifetime a password can be used to log in to a system, R is the number of guesses per unit of time, and S is the number of unique algorithm-generated passwords (the password space).

The degree of password security is determined by the probability that a password can be guessed in its lifetime.

Typically, a password maintenance routine will warn a user if he attempts to set up a password that does not meet the password length parameter, so if the value was set at 8 and the user attempted to enter the word penis as his password he would receive the message, Not long enough.

Tips for creating a good password:

• Use a combination of letters and numbers
• Don't use a word that is personally identifiable to you, ie. your name, your favourite sports team or your pet's name
• Use a combination of lowercase and uppercase letters
• Don't use words found in a dictionary. See: dictionary attack