CRC32 Tools

License

This project is licensed under the GPL v3 license.

Usage

Run the command line to see usage instructions:

$ crc32.py -h
usage: crc32.py [-h] action ...

Reverse, undo, and calculate CRC32 checksums

positional arguments:
  action
    flip      flip the bits to convert normal(msbit-first) polynomials to
              reversed (lsbit-first) and vice versa
    reciprocal
              find the reciprocal (Koopman notation) of a reversed (lsbit-
              first) polynomial and vice versa
    table     generate a lookup table for a polynomial
    reverse   find a patch that causes the CRC32 checksum to become a desired
              value
    undo      rewind a CRC32 checksum
    calc      calculate the CRC32 checksum

optional arguments:
  -h, --help  show this help message and exit

References

• Calculating Reverse CRC http://www.danielvik.com/2010/10/calculating-reverse-crc.html
• Finding Reverse CRC Patch with Readable Characters http://www.danielvik.com/2012/01/finding-reverse-crc-patch-with-readable.html
• Rewinding CRC - Calculating CRC backwards http://www.danielvik.com/2013/07/rewinding-crc-calculating-crc-backwards.html