Cryptography – learn what it’s all about

The concept of cryptography touches our lives many times per day, and that’s probably a conservative estimate. We have a pretty good idea of how it works, having dealt with public-key cryptography for things like remote git repositories or ssh tunneling without a password. But we still enjoyed reading [Tiberiu Barbu’s] primer on the subject which he calls From 0 to Cryptography.

He begins the discussion with a definition of terms but quickly moves to the topic of key distribution. If you’re using a key to decipher data, how can you make sure that key only makes it to the person whom you want reading the data? One way is to use a Diffie-Hellman key exchange. The diagram above illustrates the trade, which uses an agreed upon value (color in this example) as a common starting point, then goes from there. After working our way through the key exchange scenario [Tiberiu] then runs the gammut of other options, include Public-Key, RSA, Hash, Digital Certificate, and a few others. It’s not a long post considering how many topics it covers. If you don’t have time today, make sure to save it for the weekend.

[via Reddit]

Brute force a password protected PDF using the BeagleBone

The biggest benefit to using the BeagleBone is it’s 700 MHz ARM processor. If you’re just messing around with basic I/O that power is going unused, but [Nuno Alves] is taking advantage of its power. He built a PDF password cracker based on the $85 development board.

We recently saw how easy it is to perform basic I/O using the BeagleBone. Those techniques are in play here, used to drive a character LCD and sample a button input from the breadboard circuit. [Nuno] even published separate posts for each of these peripheral features.

The password protected PDF file is passed to the device on a thumb drive. Since the BeagleBone is running embedded Linux you don’t need to mess around with figuring out how to read from the device. A click of the button starts the process. Currently the code just uses a brute force attack which can test more than 6000 four-character passwords per second.  This is quite slow for any password more than four or five characters long, but [Nuno] does mention the possibility of running several ARM processors in parallel, or using a dictionary (or rainbow table) to speed things up. Either way it’s an interesting project to try on the hardware. You can see his video demo of the device after the break.

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EFF on securing digital information when crossing the border

The Electronic Frontier Foundation, long-time defenders of the common man’s rights in the electronic realm, has published a guide to keeping your digital devices private when entering the United States. It seems the defenders of freedom and liberty (ICE, DHS, TSA, and CBP) are able to take a few freedoms with your liberty at a border crossing by seizing your devices and copies of the data they store for up to five days. This requires no suspicion of wrongdoing, and copies of this data may be shared with other agencies thereby negating the five day limit.

Do you have a reason to protect your digital property? This is discussed in the paper. It may be confidential information, by way of a business contract or professional relationship (Doctors, Lawyers, Journalists, etc.). Or you may just want to keep your privacy on principle. No matter what your stance, the EFF has covered all the bases in this intriguing read. We think the best advice they give is to make an encrypted backup of your data on the internet, blank your computer before the border crossing, and restore it when you get to your destination. If you don’t have the data with you, it can’t be compromised. It that’s not an option, they have plenty of guidelines on cryptographic techniques.

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Hackaday Links: December 3, 2011

Honey, would you like some cheese? WHIRRRRRRRRR

[The Timmy] broke his manual cheese grater. It would be a waste to throw away a perfectly functional tool that’s only missing a handle, so he kicked it up a notch with a cordless drill. Now [Tim], “can grate with incredible speed and power for even the toughest of cheeses.” Anyone have a broken pepper mill?

The most adorable oscilloscope

We’re not much for plugging products, but this scope is really cool. It’s designed to fit on a breadboard and is smaller than some ICs we’ve seen (68000, so yes, it is). We’re wondering why there hasn’t been a homebrew version of this yet.

Now do an R/C castle

Here’s a minifig-sized R/C LEGO car made by [brickmodder]. It has a custom drive train and steering mechanism that uses the smallest servos [brickmodder] could find. How about an R/C pirate ship next?

It’s probably an ad for something

Here’s some sort of code thing that asks the question, “Can you crack it?” Apparently, it’s for UK cryptanalyst recruiting. You won’t get a 00-designation, but woo Bletchley Park.

Inverting an inverter

[Manfred] is putting an alternative energy setup on his land. Of course he needed an inverter to charge his batteries, so he went with a highly regarded (high price) box. What he got was anything but. You’re going to need at least ten minutes to go through this hilariously sad teardown of a high quality Taiwanese inverter. Oh, [Manfred] is awesome. Just look at his microhydro plant.

WWII’s top cryptography comes to a child’s toy

This toy has some upgraded internals that turn it into an Enigma machine. We absolutely love the idea, as it takes a toy that your child may have grown out of, and uses it to provide teachable moments dealing with both history and mathematics. But who are we kidding? We want to make one just because it’s a fun project.

[Sketch] grabbed this toy from a thrift store because it has a full keyboard that he can use to make his own machine. It’s powered by an Arduino, with a four-line character LCD display taking the place of the original. His post covers the methods he used to figure out the keyboard wiring, and also contains a cursory overview of how the Enigma Machine functions. See a video of the finished project after the break.

If this wet your appetite, also check out the paper Enigma Machine we covered during Hackaday’s first year.

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TPM crytography cracked

Trusted Platform Module based cryptography protects your secrets as well as your government’s secrets.  Well, it used to. [Christopher Tarnovsky] figured out how to defeat the hardware by spying on its communications. This requires physical access so it’s not quite as bad as it sounds, but this does reach beyond TPM to many of the security chips made by Infineon.  This includes peripheral security chips for Xbox 360 and some chips used in cell phones and satellite TV.

[Christopher] revealed his hack during his presentation at Black Hat 2010. The method is wicked-hard, involving removal of the chip’s case and top layer, then tapping into a data bus to get at unencrypted data. The chip still has some tricks up its sleeve and includes firmware traps that keep a look out for this type of attack, shutting down if it’s detected. Infineon commented that they knew this was possible but regard it as a low threat due to the high skill level necessary for success.

[Thanks Greg]

The Underhanded Hardware Challenge

The Polytechnic Institute of NYU is hosting an interesting embedded systems contest. They’ve constructed a solid state cryptographic device that uses a 128-bit private key. Contestants will be tasked with designing and implementing several trojans into the system that will undermine the security. The system is built on a Digilent BASYS Spartan-3 FPGA board. The trojans could do a wide variety of things: transmitting unencrypted, storing and transmitting previously entered plain text, or just shutting down the system entirely. The modified devices still need to pass the factory testing procedure though, which will measure power consumption, code size, and function. After a qualification round, participants will be given the necessary hardware to compete.

[via NYC Resistor (Happy Birthday!)]