The Touch ID of an Apple iPhone 6 Plus gold, is shown here at a Verizon store on September 18, 2014 in Orem, Utah / Getty Images

New passwords apply on fingerprint sensor-enabled devices, and feature can be turned off

Apple’s iPhones will soon have to be opened by entering six characters, rather than four.

In iOS 9, the next version of the iPhone operating system, phones that have the Touch ID fingerprint sensors will need six numbers to open them, rather than four. The system can be moved back to four digits, if six is too many.

The extra two digits make the phones much harder to break into. Six characters means that there is a million possible combinations, rather than 10,000.

The fingerprint scanner takes precedence over the passcode lock if both are enabled, meaning that iPhone owners don’t have to enter their passcode if the phone recognises their hands. But iPhone owners are still often required to enter the code, with the fingerprint sensor sometimes working less well in various weather or if people’s hands are wet.

The company has long offered users the ability to enter longer passcodes, using the full keyboard. But the new six-digit character still uses the normal 10 digit number entry screen.

The new feature is part of a run of newly-introduced security features, with Apple looking to stress privacy and safety with the new operating system. The new iOS also two-factor verification, which usually means that people can’t log into services without going through another step, liking reading a special code from an authorised phone.