LaForge Demystifies ESIM

August 22, 2023 by Elliot Williams 8 Comments

This talk at Chaos Communications Camp 2023 is probably everything you want to know about eSIM technology, in just under an hour. And it’s surprisingly complicated. If you’ve never dug into SIMs before, you should check out our intro to eSIMs first to get your feet wet, but once you’re done, come back and watch [LaForge]’s talk.

In short, the “e” stands for “embedded”, and the eSIM is a self-contained computer that virtualises everything that goes on inside your plain-old SIM card and more. All of the secrets that used to be in a SIM card are stored as data on an eSIM. This flexibility means that there are three different types of eSIM, for machine-to-machine, consumer, and IoT purposes. Because the secret data inside the eSIM is in the end just data, it needs to be cryptographically signed, and the relevant difference between the three flavors boils down to three different chains of trust.

Whichever eSIM you use, it has to be signed by the GSM Alliance at the end of the day, and that takes up the bulk of the talk time in the end, and in the excellent Q&A period at the end where the hackers who’ve obviously been listening hard start trying to poke holes in the authentication chain. If you’re into device security, or telephony, or both, this talk will open your eyes to a whole new, tremendously complex, playground.

The Rise And (Eventual) Fall Of The SIM Card

March 20, 2023 by Tom Nardi 109 Comments

There are few devices that better exemplify the breakneck pace of modern technical advancement than the mobile phone. In the span of just a decade, we went from flip phones and polyphonic ringtones to full-fledged mobile computers with quad-core processors and gigabytes of memory.

While rapid advancements in computational power are of course nothing new, the evolution of mobile devices is something altogether different. The Razr V3 of 2003 and the Nexus 5 of 2013 are so vastly different that it’s hard to reconcile the fact they were (at least ostensibly) designed to serve the same purpose — with everything from their basic physical layout to the way the user interacts with them having undergone dramatic changes in the intervening years. Even the network technology they use to facilitate voice and data communication are different.

Yet, there’s at least one component they share: the lowly SIM card. In fact, if you don’t mind trimming a bit of unnecessary plastic away, you could pull the SIM out of the Razr and slap it into the Nexus 5 without a problem. It doesn’t matter that the latter phone wasn’t even a twinkling in Google’s eye when the card was made, the nature of the SIM card means compatibility is a given.

Indeed there’s every reason to believe that very same card, now 20 years old, could be installed in any number of phones on the market today. Although, once again, some minor surgery would be required to pare it down to size.

Such is the beauty of the SIM, or Subscriber Identity Module. It allows you to easily transfer your cellular service from one phone to another, with little regard to the age or manufacturer of the device, and generally without even having to inform your carrier of the swap. It’s a simple concept that has served us well for almost as long as cellular telephones have existed, and separates the phone from the phone contract.

So naturally, there’s mounting pressure in the industry to screw it up.

Continue reading “The Rise And (Eventual) Fall Of The SIM Card” →

Cramming Dual SIMs & A Micro SD Card Into Your Phone

August 16, 2019 by Lewin Day 22 Comments

There are plenty of dual SIM phones on the market these days, but most of them are a hamstrung by packaging issues. Despite their dual SIM capability, this usually comes at the expense of the microSD card slot. Of course, hackers don’t accept such nonsense, and [Tweepy] went about crafting a solution. Sadly the make and model of phone aren’t clear.

It’s a simple case of very carefully shaving both the microSD card and the nano-SIM down until both can fit in the card tray. The SIM is slimmed down with the application of a heat gun helping to remove its plastic backing, saving precious fractions of a millimeter. The SD card is then filed down to make just enough space for the SIM to fit in underneath. Thanks to the springiness of the contacts in the phone, it’s just barely possible to squeeze both in, along with some Kapton tape to hold everything in place.

Your mileage may vary, depending on the construction of your SD card. Overall though, it’s a tidy hack that should prove useful to anyone with a dual SIM phone and limited storage. We saw a similar hack a few years ago, too.

[Thanks to Timothy for the tip!]

Printed Nexus 7 SIM Tray Is Good ‘Nuff

February 2, 2018 by Tom Nardi 9 Comments

When repairing something, there are in effect two schools of thought: you can craft a repair that seamlessly blends into the original hardware and doesn’t look like a repair, or you can slap that thing together and keep it moving. A lot of variables go into this decision making process, such as the complexity of the repair, the available materials, and of course whether or not you need to keep the fact you broke the thing from your significant other.

When the SIM holder on his Nexus 7 tablet broke recently, [Alex Whittemore] did the mental arithmetic and came to the conclusion that it wasn’t worth his time trying to figure out how to model an exact replacement. But he was able to print something that works well enough for his purposes, which is all that matters in the end. A perfect entry for our ongoing “Repairs You Can Print” contest.

Apparently the SIM holder in the 2013 Nexus 7 is notoriously poor, and of course since this is a known issue, online retailers are trying to get as much as $100 USD out of you for a tiny sliver of plastic. Sometimes it really seems like Google was determined to run the Nexus line into the ground before bailing on it.

Printing such a tiny part, especially with the little details like the channel for you to hook your fingernail into, requires a fairly well calibrated printer. If you can’t muster up a 0.1mm first layer you might as well sit this one out; and if you haven’t mastered the art of bridging, that little valley to help you get the SIM back out may end up overflowing into a river of tears.

For [Alex], the piece ended up working perfectly. It might look a little weird, but if you’ve got the tablet in a case you’ll never see it anyway. It’s also worth noting that this design may work on other devices with a similar SIM arrangement, or at the very least, might be a good starting point to work from if you’ve got to come up with your own.

Remember, there’s still plenty of time to enter your own printed fix into our “Repairs You Can Print” contest. The top 20 repairs will take home $100 in Tindie credit, and for the best repair done by a Student or Organization, there’s two Prusa i3 MK3 printers with the Quad Material upgrade kits on the line.

Hologram.io Offers Developers Free Cell Data

July 25, 2017 by Mike Szczys 68 Comments

If you’ve been thinking of adding cellular connectivity to a build, here’s a way to try out a new service for free. Hologram.io has just announced a Developer Plan that will give you 1 megabyte of cellular data per month. The company also offers hardware to use with the SIM, but they bill themselves as hardware agnostic. Hologram is about providing a SIM card and the API necessary to use it with the hardware of your choice: any 2G, 3G, 4G, or LTE devices will work with the service.

At 1 MB/month it’s obvious that this is aimed at the burgeoning ranks of Internet of Things developers. If you’re sipping data from a sensor and phoning it home, this will connect you in 200 countries over about 600 networks. We tried to nail them down on exactly which networks but they didn’t take the bait. Apparently any major network in the US should be available through the plan. And they’ve assured us that since this program is aimed at developers, they’re more than happy to field your questions as to which areas you will have service for your specific application.

The catch? The first taste is always free. For additional SIM cards, you’ll have to pay their normal rates. But it’s hard to argue with one free megabyte of cell data every month.

Hologram originally started with a successful Kickstarter campaign under the name Konekt Dash but has since been rebranded while sticking to their cellular-connectivity mission. We always like getting free stuff — like the developer program announced today — but it’s also interesting to see that Hologram is keeping up with the times and has LTE networks available in their service, for which you’ll need an LTE radio of course.

Particle Electron – The Solution To Cellular Things

February 10, 2016 by Brian Benchoff 56 Comments

Just over a year ago, Particle (formerly Spark), makers of the very popular Core and Particle Photon WiFi development kits, released the first juicy tidbits for a very interesting piece of hardware. It was the Electron, a cheap, all-in-one cellular development kit with an even more interesting data plan. Particle would offer their own cellular service, allowing their tiny board to send or receive 1 Megabyte for $3.00 a month, without any contracts.

Thousands of people found this an interesting proposition and the Electron crowdfunding campaign took off like a rocket. Now, after a year of development and manufacturing, these tiny cellular boards are finally shipping out to backers and today the Electron officially launches.

Particle was kind enough to provide Hackaday with an Electron kit for a review. The short version of this review is the Electron is a great development platform, but Particle pulled off a small revolution in cellular communications and the Internet of Things

Continue reading “Particle Electron – The Solution To Cellular Things” →

Raspberry Pi GSM Hat

February 28, 2015 by Brian Benchoff 12 Comments

The Spark Electron was released a few days ago, giving anyone with the Arduino IDE the ability to send data out over a GSM network. Of course, the Electron is just a GSM module tied to a microcontroller, and you can do the same thing with a Pi, some components, and a bit of wire.

The build is fairly basic – just an Adafruit Fona, a 2000 mah LiPo battery, a charge controller, and a fancy Hackaday Perma-Proto Hat, although a piece of perf board would work just as well in the case of the perma-proto board. Connections were as simple as power, ground, TX and RX. With a few libraries, you can access a Pi over the Internet anywhere that has cell service, or send data from the Pi without a WiFi connection.

If you decide to replicate this project, be aware you have an option of soldering the Fona module right side up or upside down. The former gives you pretty blinking LEDs, while the latter allows you to access the SIM. Tough choices, indeed.