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Encryption In The 1790s

July 23, 2026 by 7 Comments

For as long as humans have had writing, there’s been a need to send secret messages. It is easy to think that Enigma machines and their immediate predecessors are old tech, but they are much more recent than ancient systems used by the Greeks and Romans. Even Thomas Jefferson, one of the founding fathers of the United States, was interested in encryption and is often said to have invented the Jefferson Disk machine for encryption. The truth is, the device is probably older than Jefferson, but he certainly thought about using it for secret communications.

Simple but Effective

Thomas Jefferson was, apparently, a fan of secret messages

The idea is simple. We make a series of disks. Each disk has a number on it and, around the edge, all the letters of the alphabet. The placement of each wheel with the same number is the same, but, overall, the arrangement is random. That is, all disks marked #5 might start with XCBYG, but all disks marked with #10 could start with FAYQL. You take one set of disks, and I keep the other set.

When we want to send secret messages, we agree to arrange our disks on an axle in the same order. Jefferson used a 36-disk system, so we might agree to go left to right with the odd numbers first and then the even numbers, or any other setup that we could agree on.

Encryption

Once the wheels are in place, encryption is simple. There’s a bar across the device, and you line up your message using a wheel for each letter: ENEMYCOMESBYSEA, for example. Then you look at any different row, which will now read something crazy like: FSRSSXQCGAEEFOR (plus the random letters on the rest of the disks). That’s the message you send.

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The Need For Speed: Internet Speed Measurement (or DIY?)

July 22, 2026 by 9 Comments

Car enthusiasts want to know how quickly they can make a quarter mile. Weightlifters are forever trying to add one more plate to the bar. Internet denizens have their own favorite number to brag about: the result from a speed test.

The ritual is familiar. Close a few browser tabs, click the big “Go” button, and watch the needle climb. Perhaps you pay for gigabit service and see 940 megabits per second, which produces a satisfied nod. Perhaps you see 299 megabits and begin obsessing over network hardware. But before you get too excited either way, try another test. There is a fair chance it will give you a different answer.

That does not necessarily mean one test is lying. “Internet speed” is not a single physical quantity waiting to be measured. A speed test measures the performance of a particular device, over a particular local connection, through a particular ISP route, to a particular server, at a particular time using a particular test method. Change any of those things and the answer can change too. Continue reading “The Need For Speed: Internet Speed Measurement (or DIY?)” →

UDP Broadcasting And The Joys Of IPv4 Subnetting

July 14, 2026 by 35 Comments

In the previous installment on UDP broadcasting and service discovery, the basics of both were explored, including an implementation in the form of NyanSD and its protocol. Contained in the comment section was a very good demonstration of why one of the most exciting aspects of software development is the opportunity to share your latest creations with other people. This being the ability to get solid feedback on all the points – including any potential boneheaded omissions – that you really should address, whether intentional or accidental.

The most pertinent point raised was definitely that of broadcast addresses and IPv4 subnets, with the latter topic especially being something that the sysadmins at the office would talk about all the time, but which us software developers were always happy to ignore as something that didn’t concern us. Turns out the joke was on me and everyone else – like our esteemed readers – who thought that they could escape the fascinating world of subnets, as today we’ll take an in-depth look at what subnets are and how they are relevant to the world of UDP network discovery.

I somewhat alluded in the first article to the topic of ‘which broadcast address to use’ as being somewhat of a rough topic to figure out, which is clearly why I just stuck to a blatantly ‘works for me’ /24 subnet that usually will work on networks, until it does not.

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The Death Of Physical Media And The Real Challenges To Software Archiving

July 13, 2026 by 30 Comments

Along with the many displays of outrage, gnashing of teeth and other displays of profound grief at the recent news that Sony will no longer manufacture physical game discs come 2028, we have also heard some voices pipe up with a variety of statements, such as that this decision makes game archiving basically impossible. Of course, the truth of the matter is that software archiving in general has become much harder already over the past decades, while game consoles are just late to the archiving-hostile party.

As an example, one merely has to contrast Sony’s PlayStation with e.g. the Valve Steam store and software by juggernauts like Adobe and Autodesk. Here the former moved after the Creative Suite (CS6) series of Photoshop and other tools fully over to the Creative Cloud (CC) subscription model, where DRM and constant rental software renewals are in order. Unlike that disc copy of CS6 Master Collection that will stay good practically forever, there’s nothing really to archive with Adobe’s CC software.

Similarly, with digital game downloads and their constant patches now put inside a heavily encrypted environment that relies on a special launcher, preserving video games has been turned into into a virtual nightmare for many years now.

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Know Your Food: Organic Production

July 2, 2026 by 37 Comments

A few weeks ago we published the first in a new series of articles, Know Your Food. It was born out of the realisation that most people know surprisingly little about what they eat, and to apply a bit of Hackaday curiosity to received opinion on the subject. As we put it then: “To know both how common foodstuffs should be made, as well as how they are made industrially, should be an essential for everyone” We’ll continue in that vein, with a look at organic food.

If you buy your food in a supermarket it’s likely that in the vegetable aisle you’ll be presented with a choice. On one hand you will have the normal vegetable, and on the other and usually for a slightly higher price, the organic version of the same vegetable. What’s going on?

So What Is This Organic Stuff All About?

A watercolour picture of a bucolic scene with a farmhouse surrounded by trees, and some cows in the foreground.
It is unlikely that a typical organic farm in the 2020s will resemble this John Constable painting. John Constable, Public domain.

Organic production is a system of agriculture that emphasises natural fertilisers, pesticides, and farming methods over synthetic or intensive ones. It has its roots in the first half of the 20th century, and as the decades progressed it has become an important sector of agricultural industry. I grew up steeped in organic agriculture because my grandfather was an early adherent in the years following the war, so I’ve seen it from the sharpest end. There is a lot to commend organic production for and plenty of reasons to embrace it, but with that come some problematic aspects, and even dubious claims. Here I’ll try to unpick some of that.

It’s tempting to believe that all organic production is somehow a return to a 19th century rural idyl, complete with the obligatory chickens in the farmyard. Some organic producers do take a slice of this back-to-the-land approach to their craft, but the reality of organic farming is a very modern approach to managing the ecosystem. Organic farmers are not wary of progress, and neither are they reluctant to use pesticides or other chemicals. Instead they do so according to the principles of organic agriculture, so any techniques they use are designed to be beneficial to the ecosystem, and any chemicals have a natural origin. Continue reading “Know Your Food: Organic Production” →

How Airspeed Sensors Work

June 30, 2026 by 28 Comments

When you’re driving your car, you’re probably regularly looking at the speedometer to make sure you comply with the local speed limits. The method by which it works is simple enough: the rotation of the wheels is sent mechanically via a cable to a dial on the dash, or an electronic sensor counts the rotations of the drivetrain and an electronically-controlled needle or display shows the speed.

But what about if you were in an aircraft, and the wheels had nothing to do with how fast you were going? How would you even begin to measure speed? There are two ways: there’s a convenient solution to this problem rooted in simple fluid mechanics, and a far-more-complex modern solution. Today, we’ll explore how planes and helicopters are able to figure out how fast they’re going, by the old ways and the new.

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The Teenage Angst Of 3D Printing: Solidoodle, Printrbot, And Bridges

June 29, 2026 by 42 Comments

Bridges are a part of our constructed landscape that we take for granted. And bridges by themselves aren’t especially important. What is important is that bridges let you get from one place to another. Technology is often the same. We get from point A to point B through some bridge technology that, probably, most normal people never even notice.

Years ago, point A was commercial 3D printing. Industry had stereolithography, selective laser sintering, fused deposition modeling, and other rapid-prototyping technologies. These were not toys. They were expensive industrial systems used by companies that needed prototypes badly enough to pay serious money for them.

Fast Forward to Today

Today, you can go to a big box store and buy a 3D printer for well under $1,000, and often far less. Modern machines are almost plug-and-play and tend to do all the hard parts for you. That’s point B. How we got between points is a story of hackers who had a dream, and many Hackaday readers lived through it and even played a part in that bridging.

For a long time, RepRap was synonymous with hobby-level 3D printing. The project, started by [Adrian Bowyer] at the University of Bath in 2005, was built around a powerful idea: a machine that could print many of its own parts, thereby helping make more machines. RepRap Darwin reached its early self-replicating milestones in 2008, and the movement produced a thicket of descendants, variants, and arguments about rods, belts, bearings, extruders, firmware, and what “self-replicating” really meant. Of course, the machine could only print some of the parts you needed, but it was still impressive how much of a printer you could make with one printer.

Without RepRap, the desktop 3D printer boom would have looked very different. It created a common pool of ideas: Cartesian frames, printed brackets, hobbed bolts, heated beds, RAMPS boards, Marlin firmware, and a whole common vocabulary. It also created the expectation that a 3D printer was something you could understand, modify, repair, and improve. That expectation would not survive everywhere, but it defined the early culture.

Continue reading “The Teenage Angst Of 3D Printing: Solidoodle, Printrbot, And Bridges” →