Referred to internally as the 'stage 1' payload, the downloader payload is an intermittent game-independent payload. It's responsible for downloading the 'stage 2' (final) payload and verifying its RSA-SHA-256 signature before launching it.
The stage 0 code verifies the stage 1 payload against a specific hash, preventing it from being updated. So essentially it's an extension of the stage 0 payload, but stored on the server for lack of a good place to store it in game memory.
The code is very small and as such does not need a very complicated build system. The Python script make-stage1.py
includes the commands to build it. You will need the DEVKITPPC environment variable set.
Software released under other licenses are used:
- FIPS 180-2 SHA-256 implementation - Copyright (C) 2005, 2007 Olivier Gay olivier.gay@a3.epfl.ch
- RSA Verify implementation - Copyright (C) 2010 The Chromium OS Authors
The rest of the code is licensed under the same custom BSD-style license as the rest of the respository. The full text can be found in the LICENSE file.