When you install iOS 9 and your iPhone restarts, one of the first things it will ask you is to enter a six digit passcode, this will no doubt be a huge surprise to an enormous number of users who have been happily using four digits for years. This could have dire consequences for the supposed “improved security” the extra two digits are supposed to provide.
A large number of users will pick the first six digit string they can think of that is easy to remember and go with their date of birth in “yymmdd”, “mmddyy” or “ddmmyy” format. Another popular choice is going to be sticking two zeros on the end of the old four digit number or using “123456”, “654321”, “111111” or some other simple string.
If users aren’t informed about this change long before it jumps up and forces them to enter a new passcode the end result could be a dramatically reduced list of numbers to check rather than the supposed new million combinations!