The “going unnoticed” aspect is probably the most interesting part of this project. A Nintendo DSi looks far less like a Bitcoin signing device than a dedicated hardware wallet.
The main thing I’d still want to understand is the bootloader trust model. Even if the ndssigner ROM itself is verified by SHA256, how much does security ultimately depend on the external bootloader being trustworthy and untampered with?
For a device intended to cross borders unnoticed, that seems like one of the most important parts of the threat model.
I think that the bootloader is not such a threat, and the risk of tampering the ROM is minimal, but I have not analyzed its actual impact. However it is good to stay aware that there is some code running before ndssigner.
The “going unnoticed” aspect is probably the most interesting part of this project. A Nintendo DSi looks far less like a Bitcoin signing device than a dedicated hardware wallet.
The main thing I’d still want to understand is the bootloader trust model. Even if the ndssigner ROM itself is verified by SHA256, how much does security ultimately depend on the external bootloader being trustworthy and untampered with?
For a device intended to cross borders unnoticed, that seems like one of the most important parts of the threat model.