Password length & complexity
A password is something that a user knows similar to a personal identification number (PIN) we use for our bank's ATM card. Coupled with user identification, it the most common form of identification and authorization mechanism implemented in web applications. Below are advantages and disadvantages on using a password as authentication mechanism.
- easy to implement
- inexpensive (doesn't require sophisticated hardware
- easy to use (unless you forget it)
- easy to guess
- can be sniffed or brute forced
- users tend to forget their password or list them on sticky notes posted in their monitor or under the keyboard
With best practices and proper implementation guidelines, the use of password as an authentication mechanism can be a quick and easy solution.
Password length and complexity with proper password management makes the use of password as an authentication mechanism worthwhile to consider in your web application requirements. Below are best practices for password length and complexity.
- Minimum length. Passwords should be at least eight (8) characters long.
- Maximum length. Twenty (20) characters may already be long for some people. Remember, people tend to forget their passwords easily.
Note: The minimum and maximum length of password in your system can be implemented in a configurable manner. Possibly using a properties file or xml configuration file. This way, you can easily change your systems password length implementation.
- Password characters should be a combination of alphanumeric characters.
- For change password functionality, if possible, keep a history of old passwords used for the past 2 months. In this way, the user cannot change password that was used a couple of months back.