You ARE How You Browse

Think about your handwriting. Even with the same pen and paper, no two people write identically. The same is true for how you interact with a computer.

Behavioral biometrics analyze patterns in how you:

Move your mouse (speed, curves, hesitations)
Type on your keyboard (rhythm, pressure, errors)
Scroll through pages (speed, pauses, direction changes)
Interact with touchscreens (pressure, angle, gestures)

These patterns are as unique as fingerprints—and they work even when you're trying to hide your identity.

INSIGHT: Behavioral tracking is used by banks for fraud detection, by governments for identification, and by advertisers for cross-device tracking. Same technology, very different implications.

Mouse Dynamics

Your mouse movements tell a story. The speed at which you move, the curves you make, how you approach clickable targets—all unique to you.

Data Points Collected

Movement

• Average/max velocity
• Acceleration patterns
• Curvature of paths
• Direction changes

Clicks

• Double-click speed
• Click duration (hold time)
• Distance from target center
• Hover time before click

// Sample mouse event stream

{
  "events": [
    {"t": 0, "x": 100, "y": 200, "type": "move"},
    {"t": 16, "x": 145, "y": 198, "type": "move"},
    {"t": 32, "x": 210, "y": 195, "type": "move"},
    {"t": 48, "x": 285, "y": 192, "type": "move"},
    {"t": 64, "x": 350, "y": 190, "type": "click"}
  ],
  "metrics": {
    "avgVelocity": 15.6,
    "pathCurvature": 0.02,
    "targetApproachAngle": 2.3,
    "clickAccuracy": 0.95
  }
}

Research shows: Mouse dynamics can identify users with95-99% accuracy after just a few minutes of interaction. This works even when users try to disguise their behavior.

Keystroke Dynamics

The rhythm of your typing is uniquely yours. How long you hold each key, the timing between keystrokes, which keys you often mistype—all create a typing "fingerprint."

Timing Metrics

// Keystroke timing analysis

Typing: "password"

Key    | Press Time | Release Time | Hold  | Flight
-------|------------|--------------|-------|--------
'p'    | 0ms        | 80ms         | 80ms  | -
'a'    | 120ms      | 190ms        | 70ms  | 40ms
's'    | 240ms      | 320ms        | 80ms  | 50ms
's'    | 380ms      | 450ms        | 70ms  | 60ms
'w'    | 510ms      | 600ms        | 90ms  | 60ms
'o'    | 680ms      | 750ms        | 70ms  | 80ms
'r'    | 820ms      | 900ms        | 80ms  | 70ms
'd'    | 960ms      | 1040ms       | 80ms  | 60ms

Signature: [80,40,70,50,80,60,70,60,90,80,70,70,80,60]

Hold Time

How long key is pressed

Flight Time

Gap between keystrokes

Digraph

Time for key pairs

Applications:

Continuous authentication: Banks verify it's really you typing, not a bot
Fraud detection: Account takeover attempts often fail keystroke checks
Online exams: Proctoring software detects if someone else is typing
Advertising: Cross-device identity linking

Scroll & Touch Patterns

How you scroll through a page—fast or slow, smooth or jerky, the length of your swipes—creates another behavioral signature.

Scroll Metrics

Scroll velocity: How fast you move through content
Reading patterns: Where you pause, what you skip
Direction reversals: How often you scroll back up
Scroll depth: How far down you typically go

Touch-Specific (Mobile)

Physical

• Touch pressure
• Contact area size
• Finger angle
• Multi-touch patterns

Gestural

• Swipe velocity curves
• Pinch-zoom behavior
• Tap duration
• Gesture completion time

Cross-device tracking: Your behavioral patterns are consistent across devices. Touch patterns on your phone match your trackpad patterns on your laptop, enabling advertisers to link your devices without cookies or login.

Real-World Implementations

BioCatch

Used by major banks. Collects 2000+ behavioral parameters. Claims 99% accuracy in fraud detection. Tracks how you hold your phone.

TypingDNA

Keystroke dynamics authentication. Used for online exams and 2FA. Can verify identity from typing just 30 characters.

Fullstory / Hotjar

"Session replay" tools that record all user interactions. Marketed for UX research, but capture complete behavioral profiles.

Google reCAPTCHA v3

That "I'm not a robot" checkbox? It analyzes mouse movements and timing to determine if you're human. Creates a behavioral profile in the process.

The Privacy Paradox

Behavioral biometrics are simultaneously a powerful security tool (stopping fraud, preventing account takeover) and a privacy nightmare (enabling surveillance, persistent tracking). The same technology that protects your bank account can track you across the web.

Defense Strategies

Unlike canvas fingerprinting, behavioral tracking is extremely hard to defeat—your behavior is your behavior. But there are strategies:

Privacy-Focused Browsers

Brave and Firefox block known behavioral tracking scripts by default. Won't stop first-party collection but reduces third-party surveillance.

Script Blockers

uBlock Origin, NoScript can block session replay scripts (Fullstory, Hotjar). Check for known tracking domains.

Varying Your Behavior (Hard)

Theoretically possible to vary your typing/mouse patterns, but very difficult to do consistently. Research shows intentional variation often creates a new, still-unique pattern.

Input Randomizers

Browser extensions that add random noise to mouse events and keystroke timing. Experimental and may break websites.

REALITY CHECK: There is no complete defense against behavioral tracking. Your best strategy is minimizing JavaScript execution (Tor Browser), using privacy-focused tools, and being aware that sophisticated actors can still identify you.

The Bigger Picture

Behavioral biometrics represent a fundamental shift in tracking. We've moved from tracking what you do (pages visited, items clicked) to tracking who you are at a biometric level.

This has profound implications:

Anonymity erosion: Even on Tor, your behavior can deanonymize you over time
Pseudonym linking: Different accounts, same typing pattern
Cross-context tracking: Work computer behavior matches personal device behavior

The surveillance economy has evolved beyond cookies. Understanding behavioral tracking is essential to making informed privacy decisions.

Behavioral Tracking