Device fingerprint

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A device fingerprint, machine fingerprint, or browser fingerprint is information collected about a remote computing device for the purpose of identification. Fingerprints can be used to fully or partially identify individual users or devices even when cookies are turned off.

Basic web browser configuration information has long been collected by web analytics services in an effort to accurately measure real human web traffic and discount various forms of click fraud. With the assistance of client-side scripting languages, collection of much more esoteric parameters is possible.[1][2] Assimilation of such information into a single string comprises a device fingerprint. In 2010, EFF measured at least 18.1 bits of entropy possible from browser fingerprinting,[3] but that was before the advancements of canvas fingerprinting, which claims to add another 5.7 bits.

Recently such fingerprints have proven useful in the detection and prevention of online identity theft and credit card fraud.[4] In fact, device fingerprints can be used to predict the likelihood users will commit fraud based on their signal profile, before they have even committed fraud.[5]

Prior to early 2017, device fingerprinting was limited to single browsers. If a user switched browsers regularly, fingerprinting could not be used to link the user to these browsers.[citation needed] A cross browser fingerprinting method has been published[6] which allows tracking of a user across multiple browsers on the same device.


Motivation for the device fingerprint concept stems from the forensic value of human fingerprints. In the "ideal" case, all web client machines would have a different fingerprint value (diversity), and that value would never change (stability). Under those assumptions, it would be possible to uniquely distinguish between all machines on a network, without the explicit consent of the users themselves.

In practice neither diversity nor stability is fully attainable, and improving one has a tendency to adversely impact the other.

  • Diversity requires that no two machines have the same fingerprint. However, large numbers of machines are likely to have exactly the same configuration data and thus the same fingerprint. This is particularly true in the case of factory installed operating systems. One remedy is to use a scripting language to harvest a large numbers of parameters from the client machine; however, this is likely to reduce stability, as there are more parameters that may change over time.
  • Stability requires that fingerprints remain the same over time. However, by definition browser configuration preferences are not tamper proof. For example, if one measured attribute is whether the browser has cookies on or off, then a simple change of that setting is sufficient to change the fingerprint. One remedy is to reduce the number of parameters collected to only those that are very unlikely to change; however, this is likely to reduce diversity, as fewer parameters are being measured.

Active vs passive collection[edit]

Fingerprinting methods range from passive to active.

Passive fingerprinting refers to techniques which do not involve the obvious querying of the client machine. These methods rely upon precise classification of such factors as the client's TCP/IP configuration, OS fingerprint, IEEE 802.11 (wireless) settings,[7] and hardware clock skew.[8]

Active fingerprinting assumes the client will tolerate some degree of invasive querying. The most active method is installation of executable code directly on the client machine. Such code may have access to attributes not typically available by other means, such as the MAC address, or other unique serial numbers assigned to the machine hardware. Such data is useful for fingerprinting by programs that employ digital rights management.

OSI model fingerprints[edit]

Passive collection of device attributes below the web-browser layer may occur at several OSI model layers. In normal operation, various network protocols transmit or broadcast packets or headers from which one may infer client configuration parameters. Sorted by layer, some examples of such protocols are:


Collection of device fingerprints from web clients (browser software) relies on the availability of JavaScript or similar client-side scripting language for the harvesting of a suitably large number of parameters. Two classes of users with limited client-side scripting are those with mobile devices and those running privacy software or browser extensions which block ads and trackers.[11]

A separate issue is that a single device may have multiple web clients installed, or even multiple virtual operating systems. As each distinct client and OS has distinct internal parameters, one may change the device fingerprint by simply running a different browser on the same machine, unless a new[12] cross browser fingerprinting technique is used.


Consumers and their advocacy groups may consider covert tracking of users to be a violation of user privacy.[13] Computer security experts may consider the ease of bulk parameter extraction to be a browser security hole.[14]

See also[edit]


  1. ^ "BrowserSpy". Archived from the original on 2008-09-26. Retrieved 2010-01-28. 
  2. ^ "IE "default behaviors [sic]" browser information disclosure tests: clientCaps". Archived from the original on 2011-06-05. Retrieved 2010-01-28. 
  3. ^ Eckersley, Peter (17 May 2010). "How Unique Is Your Web Browser?" (PDF). Electronic Frontier Foundation. Archived (PDF) from the original on 9 March 2016. Retrieved 13 Apr 2016. 
  4. ^ "User confidence takes a Net loss". 2005-07-01. Archived from the original on 2015-10-04. Retrieved 2015-10-03. 
  5. ^ "7 Leading Fraud Indicators: Cookies to Null Values". 2016-03-10. Archived from the original on 2016-10-03. Retrieved 2016-07-05. 
  6. ^ Cao, Yinzhi (2017-02-26). "(Cross-)Browser Fingerprinting via OS and Hardware Level Features" (PDF). Archived (PDF) from the original on 2017-03-07. Retrieved 2017-02-28. 
  7. ^ a b "Wireless Device Driver Fingerprinting" (PDF). Archived (PDF) from the original on 2009-05-12. Retrieved 2010-01-28. 
  8. ^ "Remote Physical Device Detection". Archived from the original on 2010-01-10. Retrieved 2010-01-28. 
  9. ^ "Chatter on the Wire: A look at DHCP traffic" (PDF). Archived (PDF) from the original on 2014-08-11. Retrieved 2010-01-28. 
  10. ^ "Chatter on the Wire: A look at excessive network traffic and what it can mean to network security" (PDF). Archived from the original (PDF) on 2014-08-28. Retrieved 2010-01-28. 
  11. ^ "Browser Fingerprints, Zombie Cookies, & the Death of Privacy". Archived from the original on 9 June 2017. Retrieved 14 June 2017. 
  12. ^ 6
  13. ^ "EFF's Top 12 Ways to Protect Your Online Privacy | Electronic Frontier Foundation". 2002-04-10. Archived from the original on 2010-02-04. Retrieved 2010-01-28. 
  14. ^ "MSIE clientCaps "isComponentInstalled" and "getComponentVersion" registry information leakage". Archived from the original on 2011-06-12. Retrieved 2010-01-28. 

External links[edit]