[CZC]

Originally Posted by chants

Hi CZC, is there a name for the polynomial finding tool? Also can you tell us for CRC-N bits how many CRC of N bits are needed to recover the polynomial and what if there are more or less bits input into CRC function does it change this requirement?

When bruteforcing, the program finds all possible polynomials. You then narrow them down if you have several examples.

At some point in the past I was using CRCs a lot in microcontrollers and I decided to write my own tool for that.

The source code is attached, it compiles in linux and windows as a command line program.

You can use shortcuts like using hex or strings directly on the command line.

CRC generator V1.4 $

./getcrc [options] file(s)
        -z #    polynom size
        -p #    CRC polynom
        -r      reverse polynom
        -m      mirror (reflect) data
        -n      non-direct init value
        -i #    initial value
        -e #    exit value
        -c      reverse CRC
        -a      all known CRCs
        -b #    bruteforce to target CRC
        -v      verbose bruteforce
        -s      interpret filename as a string
        -f      interpret filename as a hex string
        -C      check CRC values for the "123456789" input
        -t      trace CRC generation
        -T      dump CRC table and exit