A digital fingerprint is a collection of data about a digital device, a device component, or an application (such as a browser) that uniquely identifies it.
A digital fingerprint can also be a set of data that identifies a file, such as an audio or video recording.
The process of gathering information to create digital fingerprints, as well as using fingerprints to identify a device, program, or file, is known as fingerprinting. Data can be collected either stealthily or with user consent.
Device fingerprint
Immutable or rarely changed data about a device, as well as about programs on it, can be used as parameters to identify said device. These include:
- Device brand and model
- Device MAC address
- Operating system
- Browser used and its settings (this collection of browser data is also called a browser fingerprint)
- Screen size
- Fonts installed
- Time zone and language settings
- TCP/IP configuration
Applying device/browser fingerprints
Fingerprints of devices or web clients such as browsers can be used to track users online. Among the purposes of such tracking are:
- Screening out bot-generated traffic
- Preventing identity theft and bank fraud
- Combating piracy
- Website traffic analysis
- Ad personalization
- Collection of data for sale
- Surveillance
Thus, digital fingerprints can be used for both fighting and perpetrating crime.
Audio/video file fingerprints
A digital fingerprint of a media file typically consists of fragments of the respective file, for example, the sound of a lead singer’s voice at a particular part (in terms of time) of a song. These fingerprints are used to detect illegally distributed content, for example when uploaded to YouTube, and to subsequently restrict or block it. Audio file fingerprints are also used to identify songs in apps like Shazam.
File fingerprints
A fingerprint of a text document can be generated based on a unique text pattern or document template. In particular, such fingerprints are used to detect and prevent data leaks in data loss prevention (DLP) systems.
Protection against unauthorized fingerprinting
Because fingerprinting can be used to both protect users and invade their privacy, many browsers offer some level of anti-fingerprinting protection. For example, Firefox blocks third-party requests to services known to engage in fingerprinting, while Safari provides sites with a simplified data set that is harder to uniquely associate with a specific device and user. In addition, there are various utilities and browser plugins that mask or falsify data that can be used for fingerprinting.