When it comes to passwords, I've usually used a 10 character random mix of uppercase, lowercase, special and numeric characters, and have never had any issues with these being accepted as adequate. (Before I get told off, I have a different password for each application I use!)


However, when recently setting up a new application, my 10 character password was described by the system as "weak". So I used a 19 character password (again, a random mix of characters) and this time it was described as "fair".


Given that there are 256 ASCII characters, the determined hacker has a 1 in 5.709 X 10^45 chance of striking it lucky with my 19 character password. (I say lucky - he'd be sadly disappointed at what he found after all that effort). So my question is, what lengths would one have to go to, in order to create a password that could be described as strong?