colinoflynn/crcbeagle

CRC Reverse Engineering Tool in Python

crcbeagle's Issues

Combine different length messages

Printed message suggests different length messages will be useful for the solve, this is a lie with current implementation. Should fix that to actually check solution against other lengths.

Makes more sense once the INIT value fix for #4 is done however.

Improve input parsing

Currently inputs assumed to be lists - should also parse hex strings which are often the "output" of protocol analyzers.

what is the meaning of the second argument?

in the demo

crcb.search([[165,  16,  2,  7,  85,  163,  209,  114,  21,  131,  143,  144,  52,  187,  183,  142,  180,  39,  169,  76],
            [165,  16,  2,  7,  140,  39,  242,  202,  181,  209,  220,  248,  156,  112,  66,  128,  236,  187,  35,  176],
            [165,  16,  2,  7,  113,  105,  30,  118,  164,  96,  43,  198,  84,  170,  123,  76,  107,  225,  133,  194]],
            
           [[253,  14],
            [90,  38],
            [248,  236]]
)

I know the first three lines are the sample msg, but what is the meaning of these arrays?

           [[253,  14],
            [90,  38],
            [248,  236]]

and where can I define the CRC length?
for example, with CRC RevEng, I can type something like

./reveng -w 16 -s 282FAC4DD9 2B6BACD581 2F2AAC37BC AF2EACC022

to search for the CRC-16

thanks in advance

Test Vectors Wanted

Would be nice to have some (real) examples of this working on protocols. If you've got some simple test vectors please post them to this issue. You can see the demo.py example for how it should work.

NB - I'm very lazy, please don't post wireshark captures or something, only post either Python or "raw" hex (which can convert easily, and when I fixed #2 will "just work").

The tool requires at least two messages of the same length, it's not brute-forcing the per-message CRC. This is required for the differential to work.

Add setup.py

This thing depends on crccheck so you better install that before I get around to making setup.py

Test known init values

Currently sets init value to 0 for the differential technique.

Most of the time init value is 0 or 0xFF... . Should really try known init values once the polynomial is found, as that would be very handy for users.