CRC Faker - Documentation
Content:
Introduction
Usage
Advanced Usage
Download
The CRC faker allows you to create files of arbitrary sizes with arbitrary CRC-32 values. CRC-32 is a common checksum algorithm, used for example in SFV files. Files created by the CRC faker are worthless junk - they contain random data, which is trimmed by a highly optimized brute force algorithm to make the file have the CRC you want. Thus, the CRC faker can be used to take an existing file with known CRC, e.g. from the according SFV file, and replace it with a junk file which has the same CRC.
The CRC faker has been designed for people who want to render copied software, music and videos useless. Often, these non-legal things like CD-ROM images of commercial games are broken into multiple small-size files and distributed via the internet. When up- or downloaded somewhere, the receiver checks each file's integrity by comparing its CRC-32 against the one listed in the according SFV file, which has been created by the people who split up the whole thing into smaller files, which are easier to transfer. By replacing just one of these chunks with junk, you can make the whole resulting CD-ROM image useless. You may want to spread files created by the CRC faker via FTP, file sharing networks and newsgroups to piss all those software privates off, either if you are
The CRC faker uses a highly optimized brute force algorithm to create files with the size and CRC you want them to have. On any modern machine (1.2 GHz CPU or better) it only takes 5-10 minutes in average to create the desired fake file.
The CRC faker is available for both Windows and Linux.
Although both the Windows and the Linux version come with a graphical front end, the CRC faker is primarily a command line oriented text mode application. You are encouraged to use the command line version, as it gives you more direct control. Also, the command line version can easily be used in batch files (Windows) or shell scripts (Linux) for automating a large set of tasks.
First, change into the directory where fakecrc.exe (Windows) respectively fakecrc (Linux) are in. Example:
| Windows | cd c:\downloads\fakecrc |
| Linux | cd /home/user/downloads/fakecrc |
Then, run fakecrc. It requires at least one mandatory parameter, that's the CRC you want the resulting files to have. There are two more optional parameters: the file size, which defaults to 15.000.000 bytes, and the filename, which defaults to fakefile.rar . Example:
| Windows | fakecrc 1337babe 15000000 fakefile.r07 |
| Linux | ./fakecrc 1337babe 15000000 fakefile.r07 |
This will create a 15.000.000 bytes file with name fakefile.r07 and CRC 0x1337BABE. Please be aware that the CRC you want must be specified as 8-digit hexadecimal value, i.e. same as you find it in the commonly used SFV files.
If you want to use the GUI version, just run fakecrc-gui.exe (Windows) or fakecrc-gui (Linux). The GUI is just a very primitive front end to the command line version where you can enter the three parameters. It then runs the command line version with these parameters, i.e. it must find the command line version in order to be able to run it. Thus, when using the GUI, you should place the command line version somewhere in your PATH, or run it from the directory where the command line version is located in. In Windows, this can be achieved by setting the "working directory" for the GUI program, for example when linking it from the desktop.
For the Linux version, there are two additional simple Perl scripts available. Both take one parameter, the (path and) name of a SFV file. One of them will take 1 file randomly out of all files listed in the SFV and fake it, the other one will fake all files listed in the SFV - be aware that the latter can take a pretty long time, and it's usually enough to fake one file to break the whole thing.
Click here to download FakeCRC. It's a ZIP file containing both the Windows and the Linux version. Have fun!