New Apple Watch patent reveals 'WristID' security plans so you can ditch your iPhone more often

You can unlock the iPad Air with your finger and the iPhone 12 with your face. Could the veins in your wrist unlock your Apple Watch? 

An Apple patent newly unearthed on Reddit  suggests so: it outlines a proposed method for the Apple Watch to offer Touch ID-style unlocking. Instead of a face or a fingerprint it would bounce light off the veins, hair follicles and blood vessels in your wrist.

It's unlikely to come to the Apple Watch Series 7, but it does suggest a future where the Watch is even less tethered to your phone, thanks to having its own biometric security – at the moment, the only option to unlock an Apple Watch using biometric security is via your iPhone.

The Apple Patent doesn't give it a name beyond Wearable Electronic Device Having a Light Field Camera, but we're dubbing it 'WristID', because that's too long to keep writing out. The patent was filed on 7 January 2021 and its illustrations clearly show an Apple Watch alongside a diagram of the veins in the wrist and hand and a delightful cross-section of human skin. 

According to the patent, the Watch would emit light, such as infrared light, into the “dorsal side of the forearm” and would then use a light field camera to “construct at least one image of at least one layer of the forearm near the wrist.” That construction would be able to tell the Apple Watch whether it was on the correct person’s wrist, authenticating you as the user for services such as Apple Pay. 

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What could go wrong with WristID?

Will it work? The patent is cautious, and notes that different types of skin, tattoos and levels of arm hair can affect the results. We’ve seen this previously: when Apple introduced the first Apple Watch in 2015 some people with dark skin or sleeve tattoos found that the optical heart monitor didn’t deliver particularly accurate results. 

To address this, the patent discusses using multiple forms of pattern recognition: pigmentation patterns, hair follicles and other characteristics that together would create a unique ID.

Constant, unobtrusive authentication could be interesting: unlike FaceID, WristID would work whether or not you’re wearing a mask, and unlike Touch ID it wouldn’t matter if your fingers were clean and dry, covered in ketchup or in thick winter gloves. 

It also removes an authentication step for Apple Pay, and could make Watch-based payments or iPhone unlocking happen instantly. Provided nobody cuts your arm off it’s also very secure. 

According to Apple, such a Wrist ID system “could be used for convenient access to device features without the use of passwords”, and it might also collect additional biometric data for health or fitness monitoring.

Privacy protection isn't an afterthought

The patent also provides an insight into Apple’s thoughts about privacy. The patent filing refers to “entities responsible for the collection, analysis, disclosure, transfer, storage, or other use of such personal information data” and the expectation that they will comply with privacy policies and/or practices and should not be “shared or sold outside those legitimate uses”. It also describes measures to limit or disable the camera-based authentication and its use in health apps. 

That’s a strong indication that for Apple, privacy isn’t something to think about when the product is made: it’s something to consider before it’s even a prototype.