Blowfish Extractor

A Python script to extract blowfish keys from a DS or DSi BIOS dump.

More information about the blowfish keys can be found in GBATek.

Installation

Start by cloning this repository using Git:

git clone https://github.com/xbmbmx/py-nds-blowfish-extractor.git

Enter the directory for this project:

cd py-nds-blowfish-extractor

(optional, but recommended) I recommend creating a virtual environment for Python based tools like this one. This command will create a virtual environment named venv in the project folder:

python -m venv venv

(optional, but recommended) Activate this virtual environment (command may vary depending on the shell used, assuming bash here):

source venv/Scripts/activate

Install the required dependencies using pip:

pip install -r requirements.txt

The tool and its dependencies are now installed. Continue reading for usage information.

Usage

If you installed this program using a virtual environment, make sure it is activated before running the tool.

Get help and usage information by running:

python ./extractor.py --help

For the current version of extractor.py, this should output:

usage: extractor.py [-h] -s STARTADDRESS -b BIOSFILE [-o OUTFILE] [-f]

Extract blowfish keys from dumped DS/DSi BIOS files

options:
  -h, --help            show this help message and exit
  -s STARTADDRESS, --startaddress STARTADDRESS
                        The address to start reading from, in HEX (0xFF) or INT (255)
  -b BIOSFILE, --biosfile BIOSFILE
                        The BIOS file to read the keys from
  -o OUTFILE, --outfile OUTFILE
                        The file to output the extracted keys to
  -f, --force           Overwrite the output file if already present

An example of a command to extract blowfish keys from the DS bios file ./bios7.bin to the output file ./blowfish-keys.bin, starting from address 0x30 looks like this:

python ./extractor.py -s 0x30 -b ./bios7.bin -o ./blowfish-keys.bin -f

Continue reading if you do not yet have a bios dump to extract these keys from.

Obtaining a BIOS dump

You should always dump the BIOS from your personally owned device. I do not promote the sharing of these files.

The easiest method to extract a BIOS dump from your DSi console is using dsibiosdumper (download) | dsibiosdumper (source).

Launch dsibiosdumper.nds through Unlaunch. Unlaunch lists this file as DSi_dumper.

Once launched, you should be greeted by the main screen for dsibiosdumper.nds.

Press the A button to dump all contents. The dsidump folder on the root of your SD card should now contain the following 6 files:

- bios7.bin
- bios7i.bin
- bios9.bin
- bios9i.bin
- dsfirmware.bin
- nand.bin

The files prefixed with bios can be used to extract blowfish keys. Locations of blowfish keys in each of the files can be found in GBATek. The -s/--startaddress parameter should be set accordingly when executing extractor.py

Thanks and references

• Martin Korth, for his GBATek reference document.
• Arisotura, for dsibiosdumper.