Yifan Lu | The 3DS Cryptosystem

I think one of the biggest challenge for system engineers is designing security. Recently, at the 32c3 conference, plutoo, derrek, and smea presented a series of hacks that completely defeated the security of the 3DS. As a result, people have implemented boot-time unsigned code execution (called “arm9loaderhax” in the 3DS community; other communities might relate this with ”untethered jailbreak” or “bootloader unlock”). What I want to do today is not to reveal anything novel, but look at the security of the 3DS as a whole and see what went wrong. In this deep dive, I will hypothesize the design decisions that led to the cryptosystem found on the 3DS. Then I will present the flaws that led to “arm9loaderhax.” Finally, I will summarize the findings and provide a few tips to fellow engineers in hopes that these kinds of mistakes will not be made again. (Extra details are provided in parenthesis, they are for people with deeper knowledge of the 3DS and are not required to understand the rest of the article.)