Hacking the Nintendo Alarmo

[The Running Man]

<https://garyodernichts.blogspot.com/2024/10/looking-into-nintendo-alarmo.html>

I was somewhat surprised how easily they decrypted the encrypted firmware.

"The CRYP interface is configured for AES-128-CTR, which makes things easier.
Since, in CTR mode, a keystream is created, which is then combined with the plaintext to
encrypt and decrypt files, we can simply create a large amount of this keystream using
the CRYP interface, and then combine it with the encrypted files to decrypt them"

This shouldn't be possible since they keystream should never be reused.

[Rich]

Post by The Running Man
<https://garyodernichts.blogspot.com/2024/10/looking-into-nintendo-alarmo.html>
I was somewhat surprised how easily they decrypted the encrypted firmware.
"The CRYP interface is configured for AES-128-CTR, which makes things
easier. Since, in CTR mode, a keystream is created, which is then
combined with the plaintext to encrypt and decrypt files, we can
simply create a large amount of this keystream using the CRYP
interface, and then combine it with the encrypted files to decrypt
them"
This shouldn't be possible since they keystream should never be reused.

Yes, but this is also why the usual comment re. broken crypto goes
something like:

"The cryptographic primitives are secure, it is the
use/implementation of those into a larger system that is broken".

AES-128 is secure.

AES-128-CTR is also secure, **if used correctly**.

This is yet one more in a long line of examples of "not used correctly".