There are lots of ad-hoc rules that people are happy to propose about passwords, such as:
- Pick a phrase you can remember easily, and then use the initial letters.
- A random short sequence of letters, numbers and symbols.
- A sequence of random common words (like XKCD's "battery correct horse staple").
There is also a pile of computer security research on what passwords are hard to crack.
It seems like a pretty simple empirical question to say what is the best password scheme for any given desired strength.
Can anyone point me to any research about the ease of memorizing passwords generated according to various rules?