Most user created passwords are astoundingly weak (’12345′, ‘mypass’). How do you make them stronger? Don’t give them a choice!

Here’s how to validate a password in RoR to make sure it’s strong using a regular expression (regex).
In your model add a custom validate method (after the regular validation) that adds an error unless the password is valid.

The ‘password_validate?’ method

def password_valid? self.password =~ /^(?=.*d)(?=.*[a-z])(?=.*[A-Z])(?!.*s).{8,15}$/ end

In this case the regular expression /^(?=.*\d)(?=.*[a-z])(?=.*[A-Z])(?!.*\s).{8,15}$/ is checking that the password is 8-15 characters long ‘.{8,15}’, and it contains at least one uppercase letter ‘(?=.*[A-Z])’ and one digit ‘(?=.*\d)’. Actually it also checks for at least one lowercase letter as well ‘(?=.*[a-z])’ but most users usually include that, it also checks that there’s no funky characters ‘(?!.*\s)’