/tweakcrc

CRC tools to compute a CRC32 pre-image or modify existing data to match a given CRC.

Primary LanguageC

* EDIT, 2015: moving this to GitHub for archival purposes.

* EDIT, 2011: and 10 years later it turns out I have to modify this *horrible*
piece of code. I really should rewrite this.

You can use this tool to compute a CRC32 pre-image, or to modify existing data
at a given offset to match a given CRC.

I developed this around 2000 for an exploit and it's a ridiculously bad piece of
code. It probably assumes little endianness.

It was updated for a Securitech exploit in 2006. The algorithm I developed is
explained here (in French, but it's mostly maths anyway).

This code is astonishingly bad, it's embarrassing and you should probably not
use it.

I've put this on Google Code in 2011 because someone needed it. If you need it
for serious use, e-mail me and I might rewrite it for you, properly, with
tables.

You're probably only looking for calcvect.c (and maybe crc32.c).

I'm sincerely sorry I expose you to this,

Julien

* Original README:

This is a very raw version of my CRC tools.
Give tweakcrc a file name, an offset and a target CRC and it will patch that file at the given
offset so that the CRC of the file matches the one you gave.

  -- Julien TINNES