From GameBrew - a wiki dedicated to Video Game Homebrew.
|Version||14 May 2007|
R4crypt is a program that you can use to encrypt and decrypt the DAT files from the R4DS file system as well as from M3 Simply. It operates through the windows command console and allows you to examine and edit DAT files, including _DS_MENU.DAT and CHEAT.DAT.
You can create a folder in the root of the hard disk to save typing long paths. such as E:\R4crypt.
Click Start, select the Run option and in the pop-up window, type "CMD" and enter. The command console will then appear.
Type "E:" to go to the drive where the program was and type "cd R4crypt" select the folder. Use the following commands to encrypt or decrypt files DAT.
r4crypt.exe -d _DS_MENU.DAT destination.DAT
r4crypt.exe -e destination.DAT _DS_MENU.DAT
Once a DAT file has been decrypted, you can modify it with any hex editor. Or completely replace the menu if you want to.