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Qualcomm tries again with bigger, better ultrasonic fingerprint reader

The company says the new 3D Sonic Max makes it easier and more secure to unlock a phone using an ultrasonic fingerprint.

galaxy-s10-fingerprint

Samsung uses Qualcomm's fingerprint reader technology in the Galaxy S10. 

Jason Cipriani/CNET

A year ago, Qualcomm introduced a new fingerprint sensor that uses sound waves to map the ridges on your finger and unlock your phone. It declared it to be faster and more secure than face unlock technology from companies like Samsung and other fingerprint technology that uses optical sensors to essentially take a photo of a user's fingerprints. 

Samsung jumped on board with Qualcomm's 3D Sonic Sensor and introduced it in the Galaxy S10 and Galaxy Note 10 lineups. It removed the fingerprint reader it had placed on the back of its devices and also ditched its iris scanner in favor of Qualcomm's technology. The ultrasonic fingerprint reader sat underneath the display, letting Samsung stretch the screens across the entire front of its devices. 

The only problem was the 3D Sonic Sensor didn't quite live up to its promise. Tech reviewers complained about the slow unlock speeds and difficulty they faced placing their finger on the exact right spot. Then in October, a British woman discovered a flaw that let anyone's fingerprint unlock a Galaxy S10 smartphone. All she needed was a $3 silicone screen protector. Samsung and Qualcomm worked together to issue a software update to patch that vulnerability.  

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"What we've done is collected and bought [with Samsung] multiples of these phone covers, and we've created anti-spoof algorithms that are already released into the market," Alex Katouzian, senior vice president and general manager of mobile at Qualcomm, said in an interview ahead of Qualcomm's technology conference being held this week in Hawaii. "There's nothing wrong with the fingerprint sensor design."

But Qualcomm's trying again. The company on Tuesday at its third annual Snapdragon Technology Summit introduced its new fingerprint sensor, the 3D Sonic Max. The biggest change in this new generation is its size -- it's bigger.

The fingerprint reader in the Galaxy S10 and Note 10 is Qualcomm's 4mm by 9mm sensor. In March, it unveiled an intermediate option that increased the fingerprint-recognition area to 8mm by 8mm. The new 3D Sonic Max is 20mm by 30mm, Katouzian said. 

Getting spoofed

One of the reasons why that $3 silicone cover unlocked the Galaxy S10 is because less of a fingerprint was captured, and the ultrasonic sensor got confused. 

"When you put a silicone cover on the front screen, with an already embedded image on the silicone cover, it gets mixed up with the fingerprint and can cause a mistake," Katouzian said. "We were able to, with machine learning algorithms, recognize the difference between a pattern on a silicone cover and a pattern of an image capture. A very, very limited amount of screen covers did that."

The 3D Sonic Max's fingerprint recognition area is 17 times larger. What that bigger size means is a user doesn't have to precisely place their finger over the small sensor to unlock a phone. And handset makers can implement authentication that requires two fingers, something that makes a device more secure. The bigger size also gives the phone a clearer image of the fingerprint and lets it map even more parts of the finger, Katouzian said. 

"Spoofing becomes much harder that way," he said. "Security goes up. Ease of use goes up."

That doesn't mean the 3D Sonic Max will never be spoofed by something like a $3 cover. 

"It's practically impossible to try to predict what types of patterns will be available or what types of covers," Katouzian said. "We are constantly buying different covers and different materials" to make sure the algorithm can tell the difference between a legitimate fingerprint and a spoof. 

Qualcomm tests the fingerprint sensor with thousands of covers, Katouzian said. "We have 98% to 99% coverage. But there's always some off situation where this would happen."

One thing the new sensor is not is much faster. Because it covers a larger area, the processing could be "a little bit faster, but it depends on how you position your finger while it's learning to capture your finger," Katouzian said. In practice, unlocking a phone will take about the same amount of time as with the 3D Sonic Sensor, he said. 

Katouzian said customers have committed to using the technology, and it should arrive in devices next year. He declined to give specifics, but the Economic Daily News on Tuesday reported that Apple will be one company using Qualcomm's in-display fingerprint sensor. Apple didn't immediately respond to a request for comment. 

"There are interested [handset makers], but at this point, I can't say who they are," Katouzian said. "Sometime in 2020, you'll see announcements."

Originally published at 10:50 a.m. PT
Update at 11:43 a.m. PT: Adds report about Apple using the sensor.