Digital Fingerprinting Explained

Digital fingerprinting is the identification of large data files or structures using truncated information. A fingerprinting algorithm is one that reduces a larger data set to a very small data set, sometimes called a bit string, to promote efficient identification and search protocols.

One type of common fingerprint algorithm is called a hash function. These functions change a larger data set, sometimes known as a key, into a shorter data set, which may be called a hash. These altered pieces of data help make search techniques more agile.

One type of digital fingerprinting application is related to new digital media files. Experts note that digital fingerprinting helps a user locate a specific file to verify whether a file has been altered, while actually facilitating copyright protection. This involves using a fingerprint identifier to conduct protected file searches for other online file instances. Digital fingerprinting plays other roles for average end users, such as verifying whether particular file instances have been altered.

Digital fingerprinting technology relies on complex computer-driven analysis to identify a piece of media like a song or video clip. Here's where the fingerprint analogy is born: Just like every person has a unique fingerprint, every piece of media has identifying features that can be spotted by smart software. But what good does this kind of identification really do? Sites like YouTube can scan files and match their fingerprints against a database of copyrighted material and stop users from uploading copyrighted files. Sounds simple, right? Surprisingly, people often confuse digital fingerprinting with watermarking or don't have a clear picture of what the technology entails.

Part of the problem is that the term "digital fingerprinting" can actually refer to two entirely different things. The first meaning we've already covered, but the second works from a more traditional fingerprint analogy, equating your personal computer to an online fingerprint that can be used to track your online activity. Both concepts refer to a unique identifier, but with completely different functionalities -- this second meaning has nothing to do with spotting copyrighted songs or videos. Neither one involves scanning real fingerprints, but they're pretty cool technologies anyway. Let's take a look at how they work.

Reasons for Digital Fingerprinting

The last two pages established that the term "digital fingerprinting" applies to two entirely different technologies. The thing they have in common, of course, is a computerized form of identification. Now that we've established how each technology works, let's examine how each is used. YouTube presents an easy starting point. Copyright infringement constantly threatens the video site, and in 2007 Viacom sued Google for $1 billion over clips available on YouTube [source: CNET]. Google didn't upload the clips itself, but it didn't stop users from uploading the clips, either. Policing a site as large as YouTube is a huge challenge -- how can Google keep unlicensed content out?

With digital fingerprinting. Google uses software it calls YouTube Video Identification to sort through uploaded videos and recognize copyrighted content. It also gives copyright owners the control to deny uploads or even monetize their content [source: YouTube]. This form of digital fingerprinting actually serves two purposes: It protects Google from harmful lawsuits and limits the unlicensed spread of copyrighted material. Ideally, this means both the companies that own the copyright and the companies who host that content online are protected by fingerprinting. The content isn't spread illegally, and sites like YouTube avoid nasty lawsuits.

Of course, digital fingerprinting doesn't have to be a restrictive technology. Another excellent example of fingerprinting at work is Shazam, the music identification app that can match a song's audio sample to a musical database [source: Everything Else Matters Too]. On smart phones, Shazam uses a microphone to pick up audio from a song, analyzes it, and uses that data to find a match. Shazam then pulls up a page of information on the song and artist and provides quick access to a music store where an MP3 of the song can be purchased.

We've described how digital fingerprinting can be used to track PCs across the Internet based on various characteristics that make up a digital fingerprint. That same tracking technology can be used for security, as well. Pirates and Internet users who upload and download illicit material can be identified, tracked and even arrested using the power of digital fingerprinting. And because identification doesn't rely on an IP address alone, pirates who access the Internet from different places on the same device can still be pinned down.

Obviously, tracking criminals is a noble use of digital fingerprinting -- but if this is starting to sound like an invasion of privacy to you, you might be onto something.