Best iPhone privacy measures: Touch ID
The iPhone 5s and later come with Touch ID fingerprint scanners. You can use your fingerprint to unlock the device itself, but third-party developers have for some time been able to build Touch ID into their apps - enabling you to fingerprint-protect password keepers, banking data, health data and so on. As of iOS 9.3, you can use Touch ID - and passwords, for the matter - to protect individual notes in the Notes app.
Fingerprints aren't necessarily more secure than passcodes and passwords - a reasonably long and alphanumeric passcode is extraordinarily time-consuming to crack - but they are far more convenient, which makes it much more likely that we will use them.
But the benefits of Touch ID are not straightforward, and my colleague Glenn Fleischman discusses this in a separate article, The scary side of Touch ID. As he puts it:
"Someone might be able to coerce a password from you with a wrench... But it still requires that threat and your acquiescence. [...] Mobile fingerprint sensors change that equation dramatically. An individual who wants some of your information must only get hold of your device, ensure it hasn't been rebooted, and hold an appropriate digit still for long enough to validate one's fingerprint.
"As I touch, touch, touch, I think about about Hong Kong and mainland China; about Afghanistan and Iraq; about Ferguson, Missouri, and police overreach and misconduct; and extrajudicial American operations abroad and domestic warrantless procedures and hearings about which we know few details. I think about the rate of domestic violence in this country.
"As a nonconsensual method of validating your identity wherever you're carrying a device, coupled with software that likewise recognises it, Touch ID requires a bit more thought than just registering your fingerprints."
How to improve your iPhone privacy: Here's a small related item of interest, to anyone who wishes to keep their iPhone as private as possible. It's been ruled, in the US at least, that police can force a suspect to use Touch ID to unlock a device - following the reasoning that a fingerprint is a piece of physical evidence - whereas a passcode is viewed as knowledge and is protected by the Fifth Amendment... not that there is any logical way for police to extract this information short of waterboarding.
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