Computer Fingerprinting

Race Is On to 'Fingerprint' Phones, PCs - WSJ.com

Here are excerpts.

It's tough even for sophisticated Web surfers to tell if their gear is being fingerprinted. Even if people modify their machines—adding or deleting fonts, or updating software—fingerprinters often can still recognize them. There's not yet a way for people to delete fingerprints that have been collected. In short, fingerprinting is largely invisible, tough to fend off and semi-permanent.

How to 'Fingerprint' a Computer

A typical computer broadcasts hundreds of details about itself when a Web browser connects to the Internet. Companies tracking people online can use those details to 'fingerprint' browsers and follow their users.

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Device fingerprinting is legal. U.S. Rep. Bobby Rush (D.,Ill.), proposed legislation in July that would require companies that use persistent identifiers, such as device fingerprints, to let people opt out of being tracked online.

Fingerprinting companies are racing to meet the $23 billion U.S. online-ad industry's appetite for detailed consumer behavior. Previously, the companies focused on using device fingerprints to prevent software theft or to identify computers making fraudulent transactions, in hopes of preventing future attempts.

The idea behind BlueCava's exchange is to let advertisers build profiles of the people using the devices it has identified. For instance, BlueCava will know that an IMVU fingerprint is from someone who likes virtual-reality games.

Other advertisers could then add information about that user. BlueCava also plans to link the profiles of various devices—cellphones, for instance—that also appear to be used by the same person.

Blue Cava also is seeking to use a controversial technique of matching online data about people with catalogs of offline information about them, such as property records, motor-vehicle registrations, income estimates and other details. It works like this: An individual logs into a website using a name or e-mail address.