Day: June 7, 2013

Embedded Solution For Uploading Webcam Pictures To The Cloud

June 7, 2013 by 22 Comments

carambola-webcam-uploader

We have friends watch the cats when we go out-of-town. But we always leave a server running with a webcam (motion activated using the Linux “motion” software) so we can check in on them ourselves. But this project may inspire a change. It leverages the features of a Carambola2 to capture images and upload them to Dropbox.

In the picture above the green PCB is a development board for the tiny yellow PCB which is the actual Carambola2. It is soldered on the dev board using the same technique as those HC-05 Bluetooth modules. That shielded board includes a Qualcomm SoC running Linux and a WiFi radio. The dev board feeds it power and allows it connect to the USB webcam.

There’s a bit of command line kung-fu to get everything running but it shouldn’t be out of reach for beginners. Linux veterans will know that taking snapshots from a webcam at regular intervals is a simple task. Uploading to a secure cloud storage site is not. A Bash script handles the heavy lifting. It’s using the Dropbox Application API so this will not violate their TOS and you don’t have to figure out your own method of authenticating from the command line.

IOS Keyboard Exploit Allows Brute Force IPad Lock Screen Attack

June 7, 2013 by 19 Comments

It’s quite common to have a timed lockout after entering several bad passwords. This simple form of security makes automated brute force attacks unfeasible by ballooning the time it would take to try every possible permutation. The lock screen on iOS devices like iPad and iPhone have this built in. Enter your code incorrectly several times and the system will make you wait 1, 5, 15, and 60 minutes between entries as you keep inputting the wrong code. But there is an exploit that gets around this. [Pierre Dandumont] is showing off his hardware-based iPad lock screen attack in the image above.

He was inspired to try this out after reading about some Mac EFI attacks using the Teensy 3. That approach used the microcontroller to spoof a keyboard to try every PIN combination possible. By using the camera kit for iPad [Pierre] was able to do the same. This technique lets you connect wired keyboards to the iPad, but apparently not the iPhone. A bluetooth keyboard can also be used. These external keyboards get around the timing lockout associated with the virtual lockscreen keyboard.

We’re of the opinion that this is indeed a security vulnerability. If you forget your passcode you can simply restore the device to remove it. That wipes all of your personal data which can then be loaded from an iTunes backup. Lockscreens are paramount if a device is stolen. They will give you the time you need to change any online credentials which might be remembered by the device.

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Smoothing PLA Printed Parts

June 7, 2013 by 40 Comments

We’ve seen a few advances in the finishing processes of 3D prints over the last few months that result in some very attractive parts that look like they were injection molded. Smoothing ABS prints is now a necessary skill for anyone looking to produce professional parts, but those of us using PLA for our RepRaps have been left in the cold. After some experimentation, the guys over at protoparadigm have come up with a way to smooth out those PLA prints, using the same technique and a chemical that’s just as safe as acetone.

Instead of acetone, the guys at protoparadigm are using tetrahydrofuran, or THF, as a solvent for PLA. Other PLA solvents aren’t friendly to living organisms or are somewhat hard to obtain. THF has neither of these qualities; you still need to use it in a well ventilated area with nitrile gloves, but the same precautions when using acetone or MEK still apply. It’s also easy to obtain, as well: you can grab some on Amazon, even.

The process for smoothing PLA prints with THF is the same as smoothing ABS prints with acetone. Just suspend the print in a glass container, pour in a tiny amount of the solvent, and (gently) heat it. The evaporated solvent will smooth all the ridges out of the print, leaving a shiny and smooth surface. You can, of course, hand polish it by dedicating a lint-free cloth and a pair of gloves to the task.

Apple MagSafe Protocol Hacking

June 7, 2013 by 4 Comments

[Ken Shirriff] was interested in how the Apple MagSafe works. Specifically he wanted to know what controlled the LED on the connector itself so he tore one open to see what is inside. There’s a chip present and he didn’t waste time figuring out how the MagSafe communication protocol works.

The DS2413 chip he found on the MagSafe’s tiny little PCB has just six pins. Two of these control a pair of LEDs, which give the indicator its color range.  Another pin is used for 1-wire communications. When polled the charger will return a 64-bit identification number that includes a variety of information. [Ken] looks into what data is offered from several different models of charger by using the Arduino setup above. But the results are not entirely straight-forward as he discusses in his article. The 1-wire protocol is also used to switch the LEDs. This process is the responsibility of the computer being charged, but [Ken] shows how the colors can be cycled using an Arduino (with a couple of 9-volts as a source instead of a connection to mains).