Decrypt9
Work in progress
This is a work in progress fork of Archshifts original Decrypt9, including bleeding edge new features. Any new features will eventually get pulled into Archshifts repo: https://github.com/archshift/Decrypt9
Discussion thread on GBAtemp: https://gbatemp.net/threads/download-decrypt9-wip-3dsx-launcher-dat.388831/
Generating xorpads for encrypted files
First build by running make in the project root. By default, it will build the brahma loader version of Decrypt9. If you'd like to build for use with bootstrap, run make bootstrap instead. If you'd like to build for the gateway launcher.dat browser exploit, run 'make gateway' instead.
Decrypting gamecart dumps
You can use http://dukesrg.no-ip.org/3ds/go to load the Launcher.dat on your 3DS. This should work on almost any firmware version below 9.3.
Then use ncchinfo_gen on your encrypted game (dump the game with the Gateway launcher).
Then, if you're on firmware that is less than 7.x, create/edit slot0x25KeyX.bin in a hex editor and put in the 7.x KeyX (no, I won't give it to you).
Place ncchinfo.bin (and slot0x25KeyX.bin, if on less then 7.x) on your SD card, and run the decryptor. It should take a while, especially if you're decrypting a larger game.
Credits
Roxas75 for the method of ARM9 code injection
Cha(N), Kane49, and all other FatFS contributors for FatFS
Normmatt for sdmc.s as well as project infrastructure (Makefile, linker setup, etc)
Relys, sbJFn5r for the decryptor