Hacking, HAM Radio (EA1IYR), DSP, physics and more


Release of cccrack, the convolutional code cracker

On April 6th-7th 2019, the second edition of the STARcon 2019 congress took place in the ETSIT, in which I gave a talk about the state-of-the-art of reverse engineering of convolutional encoders, and provided a proof of concept of the ideas behind the work of Mélanie Marazin, Roland Gautier and Gilles Burel to guess the encoder polynomials of the Meteor MN2 LRPT signal.

My implementation of the algorithm described in the paper was named cccrack and, due to my unfathomable lazyness, was not released since then. Since some interest has been raised about it recently, I’m releasing both the source code and the slides (in Spanish) in which I attempt to explain the specifics of this technique.

It’s important to remark that there are two versions of this algorithm, based on hard and soft decisions respectively. My implementation covers the hard version and, therefore, is extremely sensitive to noise (in fact, bit errors make this implementation useless). Since this technique is something I want to add to SigDigger, I may end up trying to figure out the soft version of the algorithm.

Stay tuned!