In part 1 we showed you how to build your own prototype RGB keypad. Today we’ll show off some new ideas we worked on to create the project and turn it from prototype to fully functional battle station er door lock.
[vector] sent in some of his other work, but I found his posts(part 1, part 2, part 3 and final thoughts) on check washing experiments pretty interesting. His results should be enough to make you think twice about writing checks. He tested a few different pens and tested them on real check using Acetone and Alcohol as solvents.
Wired recently posted an article and video detailing our friend [Chris Tarnovsky]‘s process for hacking smart cards. In the video, [Chris] shows how he strips away physical components of the chips inside the smartcards using various gadgets and chemicals.
The first step is to remove the chip from its plastic frame. After soaking it in acid for about 10 minutes, the epoxy is removed and the chip is exposed. After that the outer layer is loosened by soaking the chip in two solutions of acetone, the second being the “clean” one. Then the chip is placed on a hotplate where a drop of fuming nitric acid is applied with a dropper; the chip is washed again in an ultrasonic cleaner, removing any residue left.
[Chris] then returns the chip to the card. He will apply nail polish to act as a masking material. He scratches a hole through the polish with a needle held by a micro positioner in the area of interest. The hole is treated with hydrofluoric acid and then etched in short intervals until the desired layer of silicon is exposed. At this point, the card is fully prepped.
Now by powering the chip with the needle resting on the bus, [Chris] can read the code on the chip by sending it various commands and watching how it reacts. To see more of [Chris]‘s reverse engineering work, check out Flylogic Engineering’s Analytical Blog. It’s a enjoyable read even if you’re new to silicon hacking.
This isn’t meant to be the definitive PCB etching post. I don’t have any experience etching boards and was hoping readers could contribute their best/favorite methods for etching boards in the comments.
We’re linking to Tom Gootee’s page on toner transfer etching. The first step is to print the design on glossy paper using a laser printer. An iron is then used to transfer the toner to a prepped copper board. The board is then soaked in etchant to remove the exposed copper. The printer toner is mostly plastic and resists the etchant. Once the board is etched, Acetone is used to remove the toner. Tom has been keeping his site up to date and as his research progresses.