privacy and licensing

A Primer on Information Theory and Privacy

Electronic Frontier FoundationIf we ask whether a fact about a person identifies that person, it turns out that the answer isn’t simply yes or no. If all I know about a person is their ZIP code, I don’t know who they are. If all I know is their date of birth, I don’t know who they are. If all I know is their gender, I don’t know who they are. But it turns out that if I know these three things about a person, I could probably deduce their identity! Each of the facts is partially identifying.

There is a mathematical quantity which allows us to measure how close a fact comes to revealing somebody’s identity uniquely. That quantity is called entropy, and it’s often measured in bits. Intuitively you can think of entropy being generalization of the number of different possibilities there are for a random variable: if there are two possibilities, there is 1 bit of entropy; if there are four possibilities, there are 2 bits of entropy, etc. Adding one more bit of entropy doubles the number of possibilities.1

Because there are around 7 billion humans on the planet, the identity of a random, unknown person contains just under 33 bits of entropy (two to the power of 33 is 8 billion). When we learn a new fact about a person, that fact reduces the entropy of their identity by a certain amount. There is a formula to say how much: Continue reading.

Related Posts

Beware of Proprietary Drift The Free Software Foundation (FSF) announced yesterday a campaign to collect a clear list of OpenOffice.Or...
A Bill of Privacy Rights for Social Network Users Social network service providers today are in a unique position. They are intermediaries and hosts to our communications, conversations and connection...
The Multiple Meanings of the Term “Open” Over the last couple of months I’ve found myself involved, both actively and passively, in several conversations that contained terms like “open” or “...
Free Software: Phase Two Free software is ubiquitous. It runs everywhere on (almost) everything. The question that dominated most of the discussions at the Libre Planet Confer...
Enforcement of the GNU GPL in Germany and Europe A. Rationale for enforcement of the GPL - At present, the enforcement of the GPL license conditions is driven by single developers and organizations s...
Video, Freedom And Mozilla My LCA talk on Friday was about why open video is critically important to free software, and what Mozilla is doing about (plus a discussion of the rel...

We Recommend These Vendors and Free Offers

Launch an SSD VPS in Europe, USA, Asia & Australia on Vultr's KVM-based Cloud platform starting at $5:00/month (15 GB SSD, 768 MB of RAM).

Deploy an SSD Cloud server in 55 seconds on DigitalOcean. Built for developers and starting at $5:00/month (20 GB SSD, 512 MB of RAM).

Want to become an expert ethical hacker and penetration tester? Request your free video training course of Online Penetration Testing and Ethical Hacking

Whether you're new to Linux or are a Linux guru, you can learn a lot more about the Linux kernel by requesting your free ebook of Linux Kernel In A Nutshell.


Leave a Comment

Your email address will not be published. Required fields are marked *

*