Ask Hackaday: How Do You Keep The 3D Printer From Becoming EWaste

One thing we sometimes forget in our community is that many of the tecniques and machines that we take for granted are still something close to black magic for many outsiders. Here’s a tip: leave a 3D printer running next time you take a group of visitors round a hackerspace, and watch their reaction as a Benchy slowly emerges from the moving extruder. To us it’s part of the scenery, but to them it’s impossibly futuristic and their minds are blown.

Just because something says it's a Prusa i3, doesn't mean it is a Prusa i3.
Just because something says it’s a Prusa i3, doesn’t mean it is a Prusa i3.

Nearly 15 years after the dawn of the RepRap project we have seen a huge advancement in the capabilities of affordable 3D printers, and now a relatively low three-figure sum will secure a machine from China that will churn out prints whose quality would amaze those early builders. We’ve reached the point in our community at which many people are on their third or fourth printer, and this has brought with it an unexpected side-effect. Where once a hackerspace might have had a single highly prized 3D printer, now it’s not unusual to find a pile of surplus older printers on a shelf. My hackerspaces both have several, and it’s a sight I’ve frequently seen on my travels around others. Perhaps it’s a sign of a technology maturing when it becomes ewaste, and thus it seems affordable 3D printing has matured. Continue reading “Ask Hackaday: How Do You Keep The 3D Printer From Becoming EWaste”

Unlocking SIM Cards With A Logic Analyzer

[Jason Gin] wanted to reuse the SIM card that came with a ZTE WF721 wireless terminal he got from AT&T, but as he expected, it was locked to the device. Unfortunately, the terminal has no function to change the PIN and none of the defaults he tried seemed to work. The only thing left to do was crack it open and sniff the PIN with a logic analyzer.

This project is a fantastic example of the kind of reverse engineering you can pull off with even a cheap logic analyzer and a keen eye, but also perfectly illustrates the fact that having physical access to a device largely negates any security measures the manufacturer tries to implement. [Jason] already knew what the SIM unlock command would look like; he just needed to capture the exchange between the WF721 and SIM card, find the correct byte sequence, and look at the bytes directly after it.

Finding the test pads on the rear of the SIM slot, he wired his DSLogic Plus logic analyzer up to the VCC, CLK, RST, and I/O pins, then found a convenient place to attach his ground wire. After a bit of fiddling, he determined the SIM card was being run at 4 MHz, so he needed to configure a baud rate of 250 kbit/s to read the UART messages passing between the devices.

Once he found the bytes that signified successful unlocking, he was able to work his way backwards and determine the unlock command and its PIN code. It turns out the PIN was even being sent over the wire in plain text, though with the way security is often handled these days, we can’t say it surprises us. All [Jason] had to do then was put the SIM in his phone and punch in the sniffed PIN when prompted.

Could [Jason] have just run out to the store and picked up a prepaid SIM instead of cracking open this wireless terminal and sniffing its communications with a logic analyzer? Of course. But where’s the fun in that?

Roll The Bones Chernobyl Style

We’re suckers for the Fallout aesthetic, so anything with a post-apocalyptic vibe is sure to get our attention. With a mid-century look, Nixie tubes, a brushed metal faceplate, and just a touch of radioactivity, this quantum random number generator pushes a lot of design buttons, and it pushes them hard.

Charmingly named “Chernobyl Dice”, this little gadget comes to us from [Nathan Griffith], and appears to be one of those “Why not?” builds we love so much. The heart of any random number generator is a source of entropy, for which [Nathan] chose to use six slightly radioactive uranium glass marbles. Those feature prominently in the front panel of the device, occasionally made to fluoresce with a few UV LEDs just because it looks cool. A Geiger tube inside the case is used to look for decay events from the marbles every millisecond. After some adjustment for the bias toward zeroes due to the relative rarity of decay events, the accumulated bits are displayed on eight Nixies. The box can be set to generate a stream of random numbers up to 31 bits long and send it over a USB port, or make random throws of a die with a settable number of sides. And when it’s not doing random stuff, it can just be a cool Nixie clock.

There are lots of ways to generate the entropy needed for truly random number generation, from a wall of lava lamps to bubbles in a fish tank. They’ve all got style, but something about this one just works.

Continue reading “Roll The Bones Chernobyl Style”