Dealing with NIST's About-Face on Password Complexity
In the last few years, we've been seeing some significant changes in the suggestions that security experts are making for password security. While previous guidance increasingly pushed complexity in terms of password length, the mix of characters used, controls over password reuse, and forced periodic changes, specialists have been questioning whether making passwords complex wasn't actually working against security concerns rather than promoting them.
Security specialists have also argued that forcing complexity down users' throats has led to them writing passwords down or forgetting them and having to get them reset. They argued that replacing a password character with a digit or an uppercase character might make a password look complicated, but does not actually make it any less vulnerable to compromise. In fact, when users are forced to include a variety of characters in their passwords, they generally do so in very predictable ways. Instead of “password”, they might use “Passw0rd” or even “P4ssw0rd!”, but the variations don't make the passwords significantly less guessable. People are just not very good at generating anything that's truly random.
Read more at Computer World