Overlaying Video On Encrypted HDMI Connections

January 21, 2012 by Brian Benchoff 25 Comments

[bunnie] is up to his old tricks again. He successfully implemented a man-in-the-middle attack on HDCP-secured connections to overlay video in any HDMI video stream. There’s a bonus, too: ~~his hack doesn’t use the HDCP master-key~~. It doesn’t violate the DMCA at all.

HDCP is the awful encryption scheme that goes into HDMI-compatable devices. Before HDCP, injecting video overlays or even chroma keying was a valid interpretation of fair use. [bunnie] thinks that HDMI devices should have the same restrictions analog devices have, so he decided to funnel his own video into his TV.

The build uses the NeTV, a handy and cheap FPGA board with an HDMI input and output. [bunnie] got the FPGA to snoop the HDMI bus and decide if a pixel needs to be changed or not. This isn’t much different from what researchers in Germany did a few months ago, but unlike the academic security researchers, [bunnie] gives you a shopping list of what to buy.

As an example of his work, [bunnie] implemented something like a ‘tweet ticker’ on HDCP-encrypted video. There’s very little the NeTV setup can’t do from chroma keying, filters, or simply dumping the HDMI stream to a hard disk. Check out the slides from [bunnie]’s talk to get better idea of what he did.

[PAPPP] found a video of the talk in question. Check that out after the break.

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FLORA: A Better Arduino LilyPad

January 21, 2012 by Brian Benchoff 17 Comments

[Ladyada] has been working on FLORA, her wearable electronics platform, for a few months now. Even though it has just been announced the specs look much better than the previous queen of the hill, the Arduino LilyPad.

Going down the spec sheet for both the FLORA and the LilyPad, we see that FLORA has twice as much flash and SRAM as the LilyPad. The LilyPad has more options for I/O, but [Ladyada]’s FLORA has the benefit of not using an ISP header for programming; FLORA is completely USB-compatable. FLORA is also about a quarter-inch in diameter smaller than the LilyPad, something to take into account when you’re going for a wearable project.

On top of Bluetooth, GPS, accelerometer, compass and other modules planned for FLORA ( it doesn’t look like they’re available yet, though), FLORA has USB HID support so it can operate as a USB keyboard, mouse, MIDI device, or connect to a cell phone. If you’ve ever wanted a keytar cardigan, this is the board for you.

Check out [Ladyada]’s video demo of a LED-equipped fabric after the break.

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Trashed Hard Drive? Why Not An Engraved Clock?

January 21, 2012 by Jeremy Cook 19 Comments

So your hard drive quit working. Don’t despair, with a “little” work your disk can be repurposed into a clock like the one seen above. I made this clock after several iterations of various success, including the first revision, which was simply the platter with a clock kit from a hobby store screwed into the middle. Still a very neat effect, but if you want to actually tell what time it is, it helps to have the numbers available.

For this, you’ll need some sort of CNC machine (a kit-build router in this case), and some way to generate the Gcode to get everything cut correctly. A guide to how the logo was eventually turned into something a machine could understand is provided here. Of course if you’re not sure what logo would look good on your clock, you can always skip a few steps and engrave the our logo. In this [HAD] article, it’s conveniently provided in .dxf format, which can be converted by a CAM (computer-aided manufacturing) program into code that your machine can understand.

Check out after the break for a video of two “platter clocks” being engraved using these methods: Continue reading “Trashed Hard Drive? Why Not An Engraved Clock?” →

Computing With The Command Line

January 20, 2012 by Brian Benchoff 40 Comments

Here’s something we thought we would never see: computing with just pipes, /dev/zero, and /dev/null.

As a thought experiment, [Linus] imagined a null byte represented an electron. /dev/zero would have an infinite supply of electrons and /dev/null would make a wonderful positive power supply. With a very short program (named mosfet.c), [Linus] can use Linux pipes to control the flow of electrons between /zero and /null. [Linus] used mosfet.c with a very short shell script to create a NAND gate. From there all bets were off. He ended up creating a D flip-flop, 4-bit adder and a counter.

From a bit of cursory research, Linux has a maximum pipe capacity of 1,048,576 bytes and the maximum number of PIDs is 4,194,304 (correct us if we’re wrong). [Linus] can theoretically build some of the classic CPUs of the 70s and 80s with his pipe logic. An Intel 486 is just out of reach, though. If you give someone a NAND or a NOR they’ll eventually build a computer; we thought we’d never see this, though.

A Talking Reverse Geocache Puzzle Box

January 20, 2012 by Mike Szczys 2 Comments

Here’s a talking reverse geocache puzzle box which [Erv Plecter] built as a wedding gift for his friends. The box itself isn’t really the gift, but a surprise delivery system for a collection of cash from the couple’s circle of friends to go toward the honeymoon. We think this is about fifty times more fun that getting a fat envelope of bills. Who would really expect to find cash inside once you finally get to the target location?

Unlike the other geocache box we saw recently, this one has no display to show you clues to the destination. Instead, it plays back audio clips which [Erv] recorded himself. They’re quite tongue-in-cheek which is another nice personal touch. The pin seen protruding out of the right side of the box can be removed to play a clue and check the location. It’s connected by a little chain to a 5 euro-cent piece which conceals an emergency release mechanism for the lid. The device is powered with a Lithium battery and can be recharged without opening the box via a USB port in the side.

We’ve embedded the video demonstration of the box after the break.

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Numerous Quiz Buttons Built On The Cheap

January 20, 2012 by Mike Szczys 3 Comments

[Sprite_TM] was tapped to build a rather large quiz buzzer system. Judging from his past work we’re not surprised that he seemed to have no trouble fulfilling the request. As the system is not likely to be used again (or rarely if it is) he found a way to finish the project that was both quick and inexpensive.

Each buzzer consists of a base, a button (both mechanical and electrical), and a couple of LEDs to indicate who buzzed in first. The mechanical part of the button uses a plastic bowl from Ikea and a wooden dowel surrounded by some pipe insulation. A momentary push switch is glued on the top of that dowel, and the insulation projects above that just a bit. This way it acts as a spring. The Dowel has been sized so that the bowl lip will hit the wooden base just as it clicks the switch.

As you can see, all of the buzzers are interlinked using Ethernet cable. The real trick here is how to read 14 buttons using just one CAT5 cable. This is done with the clever use of a 4×4 button matrix for a total of 16 buttons. The matrix also includes the LEDs for each buzzer. Since CAT5 has four twisted pairs this works out perfectly.

Looking for a more robust system thank this? Here’s a pretty nice one.

Simple Machining Process Repairs Broken Control Knob

January 20, 2012 by Mike Szczys 49 Comments

[Francisco] is helping his mother with a repair to the headlight knob on her Ford Ranger. Above you can see the broken knob on the left, and what it is supposed to look like on the right (taken from [Francisco’s] own vehicle for reference). We’ve encountered split shafts on plastic knobs before and decided it was not something that could be fixed. But he didn’t give up so easily. He mentions that you can purchase a replacement for a few bucks, but he has the means to repair the knob by machining a metal bushing.

The idea is that you mill a metal ring whose inner diameter matches what the outer diameter of the plastic shaft should be. By inserting the broken knob in the ring, the plastic is held tightly together as if it had never broken. In the video after the break [Francisco] uses a metal pencil body from his junk box and a mini-lathe to cut the bushing to length, and mill the inner diameter to his specifications.

He talks about the difficulty of getting replacement parts in Chile, where he lives. But we think this kind of thrift is a great example for all hackers. If you’ve got the tools why not use them? And if you don’t have them, here’s a great excuse to procure them!

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