I haven’t posted in a while and this seems to annoy some people so I’ll give a brief update on what’s been going on.

• I finished my sophomore year of classes at Rensselaer Polytechnic Institute and celebrated my one-year anniversary with Julia.
• Last month I pushed a new external build system for Adium. It replaces a tangle of shell scripts we used to use to build libpurple, and makes it simpler to build Universal Binaries of all of our library dependencies. It also puts us a step closer to compiling Adium 64-bit clean, and should simplify the matter of getting voice and video support once the Pidgin folks have it ready.
• I worked a little bit on setting up a download tracking system, temporarily seen in the tab bar along the top of the site. It was deficient in a lot of ways so I’ll come up with some other way to manage things.
• Alacatia Labs gave up, since no one showed any interest in the products that Joe and Jon wrote. I’m disappointed about it because the four of us are pretty talented, but we couldn’t get our acts together to make it work. I’m working on getting something new up in its place.
• I went through an old hard drive of mine and found some content from days past. Once I straighten out some administrative changes to the site, I’ll put them up for archival purposes.

My travel itinerary for a trip to Ireland included a significant amount of time at 5 separate airports (Albany, O’Hare, Dublin, Heathrow, and Dulles). I was annoyed that wi-fi is only available at Albany—each airport after asked me to pay some ridiculous fee to gain access. At one airport, I connected to an SSID and tested the waters by loading Google; I was taken instead to a video advertisement. But rather than give me ‘net access for watching the ad, I was then asked to pony up $10 for the day!

Here’s a list of airports which have free wireless Internet access. My idea: Next time I’m trying to plan a trip on Kayak, give me a checkbox that limits the search to airports on this list. The airports which signed a Faustian agreement with Boingo and others of its ilk will notice a small but unmistakeable drop in traffic, and would therefore be discouraged from renewing their festering contracts.

Back in July of 2006, I wrote a post on a previous instantiation of this blog about a puzzle:

I came up with a puzzle which seems simply enough but is actually fairly hard to solve: Find the shortest string in which all possible g-digit combinations of the numbers [1, b] are present. The easiest solution would be to simply concatenate every combination, but this is almost never the shortest one. For example, for all 2-digit combinations of the numbers [1, 3], the easiest solution would be 111213212223313233, but 1121322331 is much shorter and still contains 11, 12, 13, and all the other combinations.

I competed against Asher Dunn to devise the fastest algorithm to generate such strings, but our algorithms were painfully slow.

I hadn’t thought about the puzzle until today, when my Graph Theory professor brought up de Bruijn graphs. Expressed more eloquently than the above quote, “an n-dimensional de Bruijn graph of m symbols is a directed graph representing overlaps between sequences of symbols.” By traversing the graph in an Eulerian or Hamiltonian path, you construct a string (a de Bruijn sequence) which solves my original puzzle.

The original inspiration for the puzzle was a password-protected answering machine requiring a PIN: With each key press, the last 4 digits entered are compared with the secret code until access is granted. As it turns out, I’m not the first person to have this idea; Stefan Geens has a thorough article on the topic, well-worth the read.

The Poly wireless network is secured with a WPA2 pre-shared key. To limit access to the network to active staff, the sysadmin has set a script to run every Thursday to pull three words at random from /usr/share/dict/words. The password is e-mailed to the staff mailing list.

Hello, Poly staff. This is a weekly e-mail to provide the most recent WPA2-PSK key for accessing the wireless network in the Poly office. You will need this key to connect to the network wirelessly.

This week, the key is:
repeat seismologist minibuses

While the security is appreciated, the system is a bit annoying, as when I come in the office Mac OS X prompts me for the wireless network key. This is followed by me digging through my inbox for the latest e-mail (assuming it downloaded) and copying the password to the field. Repeat once a week.

Thankfully, Mail.app’s rule system can run an AppleScript in response to an e-mail fitting a certain description. Drawing on my limited knowledge of the language, and relying on a numerous examples online, I hacked together a script which will pull passwords out of similar e-mails. It then replaces the old saved password in your Keychain with the new one, so the next time your computer sees the network it will automatically authenticate without a prompt. Get it here.

The script can be easily customized to fit your needs. At the top of the file, just redefine the variables networkSSID, marker, and wordCount. Since these might not be obvious, networkSSID is the name of the network as it appears in the AirPort menu; marker is a unique string that immediately precedes the key (see above); and wordCount is the number of words in the password (delimited by spaces).