August 9, 2025
2 min read
Device fingerprinting is a technique that generates a unique identifier for a device by aggregating multiple attributes derived from its hardware and software environment. Key attributes include:
These elements combine into a device hash or hardware hash, producing a unique device ID. This ID enables tracking across sessions without storing data directly on the device, unlike cookies. As highlighted by Acar et al. (2014), “device fingerprinting leverages passive data collection from HTTP headers and browser APIs to construct identifiers resistant to deletion” [^1].
Device fingerprinting's persistence and relative invisibility make it more robust than traditional cookie-based tracking. Users can delete cookies or use incognito modes, but fingerprinting remains effective because it relies on inherent device properties rather than stored files.
The effectiveness of device fingerprinting stems from the high entropy of combined attributes. While a single attribute such as screen resolution or user agent is insufficient to uniquely identify a device, their combination increases uniqueness exponentially. Eckersley (2010) demonstrated this by showing that the probability of collision (two devices sharing the same fingerprint) is very low when multiple attributes are combined.
However, some challenges persist:
In summary, device fingerprinting produces a near-unique device identifier by merging diverse configuration and usage data points. Its resilience against deletion or blocking mechanisms underscores its growing role in online tracking technologies.
[^1]: Acar, G., Eubank, C., Englehardt, S., Juarez, M., Narayanan, A., & Diaz, C. (2014). The Web Never Forgets: Persistent Tracking Mechanisms in the Wild. Proceedings of the 2014 ACM SIGSAC Conference on Computer and Communications Security. https://dl.acm.org/doi/10.1145/2660267.2660349
