The most typical type of Passcode's are four-digit pins. Even if you have an iPhone 5s, the pin is still required, and can override your fingerprint.
Now for most of us, four digits is the great middle ground between, security and convince. But! Four digit pins are also the easiest to crack. Just imagine, while there are a lot of combinations to guess, it would only take a brute force computer about 11 seconds to crack, guessing at about one thousand guesses per second.
So what if you want a more secure passcode? There is that option available in iOS. And you could create a passcode that could take more than a century to crack!* To do this, you'll need a passcode that uses the iOS keyboard instead of the number pad.
To set a longer passcode, that uses the full iOS keyboard:
1. Open Settings.
2. Tap General.
3. Then Passcode Lock.
4. Switch off Simple Passcode.
5. You can now choose a Passcode, using the full keyboard.
So what is this awesome passcode? Here's it is! An example of a passcode that would take 18 centuries to brute force*:
1*)-b10-%NQ
(don't use this password...)
If we examine this, the key to a strong passcode (or password) is randomness. No names, or words, or mix of the two. You ideally want a password that is a mix between: letters, numbers, and special characters, that makes no sense, with the length of at least 11 characters.
GRC's Password Haystack website has a great tool where you can test your own passcode's or passwords, and see how long it would take for them to be brute forced.
As long as your hackers couldn't access your iDevice in some other way, like through some secret back-door program, it would be almost impossible for them to use brute force to guess your passcode.
But, hey, let's be honest. Unless your some top secret spy, a Passcode that long, and difficult to enter every time you want to unlock your iOS device, is way too over the top! (and what if you forget it!) But you can still make your Passcode a little more difficult to guess, while still having the code convenient.
All you need to do is make a short password (5+ characters) using a combination of, letters / symbols / numbers together, or even just 5+ numbers. While the numbers won't stand up against a brute forcing computer, it can stop other people. That is, as long as your Passcode isn't, 1-2-3-4-5-6...
