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Major data breaches are a near-daily occurrence. Cyberthieves have been obtaining billions of passwords and other sensitive personal information. Behavioral biometrics is a new emerging security tool. The way you press, scroll and type on a phone screen or keyboard can be as unique as your fingerprints or facial features. To fight fraud, a growing number of banks and merchants are tracking visitors’ physical movements as they use websites and apps.

Some use the technology only to weed out automated attacks and suspicious transactions, but others are going significantly further, amassing tens of millions of profiles that can identify customers by how they touch, hold and tap their devices.

Using sensors in your phone or code on websites, companies can gather thousands of data points, known as “behavioral biometrics,” to help prove whether a digital user is actually the person she claims to be. The data collection is invisible to those being watched.

The Royal Bank of Scotland, one of the few banks that will talk publicly about its collection of biometric behavioral data, started testing the technology two years ago on private banking accounts for wealthy customers. It is now expanding the system to all of its 18.7 million business and retail accounts. When clients log in to their accounts, software begins recording more than 2,000 different interactive gestures. On phones, it measures the angle at which people hold their devices, the fingers they use to swipe and tap, the pressure they apply and how quickly they scroll. On a computer, the software records the rhythm of their keystrokes and the way they wiggle their mouse.

The bank is using software designed by a small New York company called BioCatch. It builds a profile on each person’s gestures, which is then compared against the customer’s movements every time they return. The system can detect impostors with 99 percent accuracy, BioCatch says.

According to nytimes.com, privacy advocates view the biometric tools as potentially troubling, partly because few companies disclose to users when and how their taps and swipes are being tracked.

“What we have seen across the board with technology is that the more data that’s collected by companies, the more they will try to find uses for that data,” said Jennifer Lynch, a senior lawyer for the Electronic Frontier Foundation. “It’s a very small leap from using this to detect fraud to using this to learn very private information about you.”