Nerdland is Moving

7 July 2010 @ 15:15
by Tyler McHenry in Site News

Update 11 July 2010: The move was a lot more painless than I had anticipated, and is already done. If you’re reading this, then your DNS has updated and you are accessing the new server. Hooray! See below about user accounts if you missed the original announcement.

Sometime later this month, Nerdland will be moving. The content and URL of the site won’t change; only the hosting provider will. The new host will be a Rackspace Cloud Server. This probably doesn’t affect you directly unless you are one of the people to whom I gave a Nerdland “user account” with web hosting space and e-mail over the past eleven years. If you are one of those people, please read the next few paragraphs.

As part of the move, I’m going to take the opportunity to clean out a lot of cruft that’s been building up on the Nerdland server over the past half-decade since the last hosting change. Most of the user accounts that I provided for friends and relatives aren’t being used anymore, and aren’t linked from anywhere on the Internet, so there’s no reason to migrate them. Rest assured, nothing will be permanently deleted. I’m an incorrigible data pack-rat, so I’m of course going to archive and back-up everything, including what I don’t move to the new server. If you had data stored on Nerdland, you can always contact me in the future, and I will gladly send you a copy of your old files and unretrieved e-mail, or restore your data and account to the server.

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“Code”: Mass Noun versus Count Noun

15 June 2010 @ 10:45
by Tyler McHenry in Opinion

In English, there are generally two ways of describing quantities: mass nouns, and count nouns. Count nouns are used when the quantity in question is a set of discrete items. “There are twelve bananas.” Here, ‘bananas’ functions as a count noun, which is appropriate because you can clearly tell where one banana ends and the next begins. In contrast, mass nouns are used when the quantity is continuous and not divisible into countable units. “There are twelve peanut butters,” for example, does not make sense. What constitutes a single “peanut butter”? Unlike with a count noun, a unit is required to refer to a specific quantity of a mass noun, even if the unit is implicit, such interpreting the previous example to mean “There are twelve jars of peanut butter.”

This brings me to the word “code”.

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Understanding the Five Aspects of Cryptographic Security

11 March 2010 @ 11:00
by Tyler McHenry in Security

Encryption on the Internet has come a long, long way from the oft-ignored little yellow key in the lower left corner of your Netscape Navigator status bar. Today, cryptography is a vital part of all of our Internet lives, whether we realize it or not. Now, if you’re reading this article on Nerdland, chances are that you’re well aware of that, and I don’t need to explain why you need to be sure your online banking is done over an HTTPS connection, and why connecting your laptop to an open, unsecured wireless network is usually a bad idea.

But the little stuff can trip you up just as easily, and if you don’t have a solid understanding of the different facets of cryptography, you may well think that a system meets your security requirements when it does not. After all, modern cryptography is just mathematics. There’s no inherent application for it. Security isn’t a tangible property either; it’s an umbrella term for a whole class of goals. Rather, privacy, authentication, identification, trust, and verification — mechanisms of applied cryptography — are what provide the most commonly desired types of security. Understanding what these terms really mean, how they are implemented, and how they are different is essential to a true understanding of how encryption works to assure your security on the Internet, and even within a single computer.

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Designing Painless Protocols

29 December 2009 @ 20:28
by Tyler McHenry in Programming

Of the several programming jobs I’ve had in my (still relatively short) career, the one thing I’ve had to do the most frequently is implement networking protocols. I’ve implemented standard protocols defined by RFCs, I’ve implemented in-house proprietary protocols, and I’ve implemented experimental protocols for academic research. I’ve yet to be asked to design my own from the ground up, but I have developed a good feel, from an implementer’s perspective, of what works and what doesn’t when it comes to legible, extensible, and robust protocol design.

The point of this post is not to give a guideline for how to design protocols that work well, or are efficient. That is a topic of much larger scope, and if you’re interested in that, RFC 3117 is a good jumping-off point. Rather, this post aims to give a set of suggestions for how to design protocols that will be the least painful for yourself and other programmers to implement, debug, and apply. There is an underlying assumption here that you have already spent the time to decide what your protocol is trying to accomplish and that you have found a way to make it work well (assuming that it is implemented correctly).

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The Markovian State Space of War

20 August 2009 @ 18:25
by Tyler McHenry in Mathematics

When I was a kid, one of my favorite card games was War. In retrospect, I don’t really understand why I got so much enjoyment out of it, given that there is absolutely no strategy to the game whatsoever. If you happened to miss this game during your childhood, the rules are simple:

The deck is divided evenly between the players face-down. Each player reveals his top card, and the player with the higher card puts both the cards on the bottom of his deck. If the cards are of equal value, each player plays three face-down cards and a fourth face-up card, and the higher-valued card wins all the cards on the table. This is known as a war. In the case of another tie, the process is repeated until there is no tie.

A player wins by collecting all the cards. If a player runs out of cards while dealing the face-down cards of a war, he may play the last card in his deck face-up and still have a chance to stay in the game.

As you can see, since the player has no knowledge of which cards are in their initial hand, and no choice in which cards to play, this game could just as easily be played by a properly trained parakeet. The mechanical gameplay and lack of strategy, however, makes certain questions about the game mathematically interesting.

The other day when this game popped into my head, one of the first things I remembered about it was how many games I left unfinished due to their sheer length. I suddenly became curious about the expected number of turns required to finish a game of War.

It turns out that the answer is “about 277″ (which is considerably less than I expected). You see, people on the Internet tend to be pretty big nerds, and certainly I wasn’t the first one to consider writing a War simulation to figure out these kind of statistics. What I didn’t see discussed, though, is any treatment of the structure of a game of war.

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