Touch Event Radius and Force as Behavioral Biometrics on Laptops with Touchscreens

[BadB]

How even rare touches on hybrid devices create a unique profile

Introduction: A Touch That Gives Away Everything​

You use a hybrid laptop (2-in-1) with a touchscreen. You rarely touch the screen — only to scroll a page or close a pop-up window.
You're sure, "This won't affect my profile".
But you're instantly blocked.

The reason? Touch Event Radius and Force — microscopic parameters of each touch that:

• Measure the contact radius (finger area),
• Record the pressing force (pressure),
• Analyze the angle of inclination (azimuth/altitude).

This data is behavioral biometrics, which creates a unique fingerprint even if you touch the screen once every 10 minutes.

In this article, we'll explore how touch events work, why hybrid devices generate them, and how even a single touch can reveal your hardware.

Part 1: What are Touch Event Radius and Force?​

Technical definition​

When you touch the touchscreen, the browser generates a TouchEvent event with detailed parameters:

Property	Description	Unit of measurement
radiusX / radiusY	Radius of the contact ellipse	Pixels
force	Pressure force	0.0–1.0 (normalized)
azimuthAngle	Horizontal finger angle	Radians
altitudeAngle	Vertical angle of the finger	Radians

Key fact:
These values depend on the user's physiology and sensor type - and cannot be faked at the JavaScript level.

Part 2: How Sensors Affect Data​

Device Type Table (2026)​

Device	Sensor type	RadiusX/Y accuracy	Precision force
Microsoft Surface Pro 9	N-trig	±0.5 px	±0.02
Lenovo Yoga 7i	Wacom AES	±0.3 px	±0.01
HP Spectre x360	Synaptics	±0.7 px	±0.03
Dell Inspiron 2-в-1	Goodix	±1.2 px	±0.05

Anomaly example:
You claim it's a Surface Pro, but radiusX = 8.7 px → the system sees: "It's a Dell with a cheap sensor" → fraud score = 95+

Part 3: How Fraud Engines Use Sensory Data​

Analysis process (Forter, Sift)​

Step 1: Collecting Reference Profiles

• The system knows:
  • Surface Pro: radiusX = 5.2 ± 0.5 px,
  • Dell Inspiron: radiusX = 8.5 ± 1.2 px.

Step 2: Compare with the current profile

• If your profile:
  • radiusX = 8.7 px,
  • force = 0.42,
• The system compares with the base → determines: “This is a Dell Inspiron”.

Step 3: Correlate with behavior

• Hybrid devices: rare touches + active use of the mouse,
• Tablets: constant touches,
• Desktops: no touch at all.

Entropy:
The combination of radiusX/Y + force gives an entropy of 18–22 bits → 1 in 4 million.

Part 4: How to Test Your Vulnerabilities​

Step 1: Use test sites​

• https://browserleaks.com/touch — shows touch entropy,
• https://amiunique.org — detailed analysis.

Step 2: Run a local test​

// Touch handler
window.addEventListener('touchstart', e => {
const touch = e.touches[0];
console.log('Radius X:', touch.radiusX);
console.log('Radius Y:', touch.radiusY);
console.log('Force:', touch.force);
console.log('Azimuth:', touch.azimuthAngle);
console.log('Altitude:', touch.altitudeAngle);
});

Rule:
If radiusX > 7 px on the declared Surface Pro → you have already been issued.

Part 5: How to Protect Yourself from Touch Biometrics​

Device level​

Use desktop only

• Laptops without a touchscreen → no data for analysis,
• Hybrid devices → always vulnerable.

Disable the touch screen

• Windows:
  powershell:
  

  # Disable touchscreen
  Get-PnpDevice | Where-Object {$_.FriendlyName -like "*HID-compliant touch screen*"} | Disable-PnpDevice -Confirm:$false

• Linux:
  

  xinput disable "ELAN Touchscreen"

Browser level​

Dolphin Anty

1. When creating a profile,
2. In the Input section,
3. Select: "Disable Touch Events".

The hard truth:
If the touchscreen is active, you're vulnerable.
There's no way to fake radiusX/Y.

Part 6: Why Most Carders Fail​

Common Mistakes​

Error	Consequence
Using a hybrid laptop	Random touches → biometrics collected
Ignoring Touch Events	They think it's "just a sensor" → failure
Mixed use of mouse and touchscreen	Creates a unique pattern → flag

Field data (2026):
78% of failures on hybrid devices are related to Touch Biometrics.

Chapter 7: Practical Guide - Safe Operation​

Step 1: Use desktop only​

• Laptop without touch screen (Dell Latitude, HP EliteBook),
• Or bare metal RDP without a sensor.

Step 2: Disable the sensor (if applicable)​

• Run the commands above,
• Reboot the system.

Step 3: Test it out​

• Make sure there are no touchstart events,
• Even if touched accidentally.

Result:
Complete lack of sensory data → low fraud score.

Conclusion: Touch is a new imprint​

Touch Event Radius and Force aren't just "sensor data". They're a physical fingerprint of your finger and screen that can't be faked.

Final thought:
True anonymity begins not with disguise, but with refusing to reveal yourself.
Because in the world of biometrics, even a touch can give you away.

Stay on your desktop. Stay out of touch.
And remember: in the world of security, your finger is your password.