Designing taiHEN: A CFW Framework

I take software design very seriously. I believe that the architecture side of software is a far more difficult problem than the implementation side. As I’ve touch upon in my last post, console hackers are usually very bad at writing good code. The code that runs with hacks are usually ill performing and unstable leading to diminished battery life and worse performance. In creating taiHEN, I wanted to do most of the hard work in writing custom firmwares: patching code, loading plugins, managing multiple hooks from different sources so hackers can focus on reverse engineering and adding functionality.

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taiHEN: CFW Framework for PS Vita

Ever since I first bought the Vita, I have dreamed of running a custom firmware on it. I don’t mean just getting kernel code running. I want an infrastructure for adding hooks and patches to the system. I want a system for patching that was properly designed (or actually has a design), clean, efficient, and easy to use. That way, firmware patches aren’t a list of hard coded offset and patches. I’ve seen hacks that busy loops the entire RAM looking for a version string pattern so it can replace it with a custom text. I’ve seen hacks that redirect the “open” syscall so every file open path is string compared with a list of files to redirect. The examples go on and on. Needless to say, good software design is not a strong point for console hacking. For HENkaku, we did not commit any major software development sins, but the code was not perfect. It had hard coded offsets everywhere, abuse of C types, and lots of one-off solutions to problems but it got the job done. Part of the reason we didn’t want to release the source right away was that we didn’t want people to build on that messy code-base (the other reason was the KOTH challenge). I remember the dark days of 3DS hacking where every homebrew that needed kernel access would just bundle in the exploit code. This is why I decided to create taiHEN.

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HENkaku KOTH Solved

When HENkaku was first released, we posed to the community the KOTH challenge to get more hackers interested in the Vita. This week, two individuals have separately completed the challenge and are the new kings of Vita hacking! Mike H. and st4rk both proved that they have the final encryption key, showing that they solved the kernel ROP chain. I highly recommend reading their respective posts as they give some great insight into how hacking works. I also know of a third group who might have also completed the challenge but wishes to keep quiet for now. Congratuations to them too!

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Array Shuffling with Additive Generators

I was working on unit tests for a project and I wanted a fast and easy way to create random permutations of a range of numbers. That reminded me of some things I’ve learned in elementary number theory that I thought I might share with you. There is nothing new or non-trivial in this post, but I am always excited about sharing a concrete application for abstract mathematics.

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