Audio

At a high level, audio fingerprinting involves measuring the unique characteristics of a user’s device audio stack (including both hardware and software components) and then converting these measurements into a distinct identifier or ‘fingerprint’. This fingerprint can be used to track users across sessions and websites, even if they clear their cookies or use private browsing modes.

Several factors can influence the creation of a unique audio fingerprint:

• Hardware differences: Different models and brands of sound cards can produce slight variations in audio output.

• Software variations: Different audio drivers, operating system settings, and browser implementations can cause variations in audio processing.

• Browser implementations: Web browsers may have varying methods of handling and processing audio content.

How is Audio Browser Fingerprinting Implemented in JavaScript?#

Utilizing the Web Audio API, developers can produce a specific sound signal in the browser and then analyze the output to identify the aforementioned variations. Here’s a simple outline of the steps involved:

1. Sound Generation: Use the Web Audio API to generate a specific sound pattern or frequency in the user’s browser.

2. Sound Analysis: Analyze the audio output for any minute differences that might arise from device-specific characteristics.

3. Conversion to a Fingerprint: Convert the analysis into a hash or unique string that acts as the user’s fingerprint.

const context = new (window.AudioContext || window.webkitAudioContext)();
const oscillator = context.createOscillator();
const analyser = context.createAnalyser();

oscillator.connect(analyser);
oscillator.start(0);

// After a short delay, read the audio data
setTimeout(function() {
    const freqData = new Uint8Array(analyser.frequencyBinCount);
    analyser.getByteFrequencyData(freqData);

    // Convert the frequency data into a unique fingerprint
    const fingerprint = freqData.join('');
    console.log("Audio Fingerprint:", fingerprint);
}, 500);

Techniques to Bypass Audio Browser Fingerprinting#

Audio fingerprinting alone is not used as a main technique as it is not very reliable but can be used combined with other technique as an another data point. Main way of comparing fingerprints is through direct comparison to a database.

In case of Audio fingerprinting actually making a difference in your bypass success-rate, bypass can be achieved through artifacts injection in the audio engine of the browser, or through artifacts and small variations injections directly in the functions returns such as getByteFrequencyData.