Wii Uses Elliptic Curve Cryptography For Saves

[wraggster]

via /. (http://games.slashdot.org/article.pl?sid=07/09/16/0317204)


A user at the Nintendo-Scene forums just posted a lengthy post about his discovery that the Wii savegame files are signed and encrypted with NIST B 233 bit elliptic curve cryptography. Could this be the first step for a Wii softmod the homebrew community have waited for? From the post: 'It appears a Wii savegame file ends with a certificate chain. The certificates contains a public keypair (the one that is being "certified") and a signature (another number pair) from the signing entity. The number pairs are stored as a compound 60 bit data (first 30 bytes for the first number, and the next 30 bytes for the second). Hence, the first and middle byte is always 00 or 01 for keys, and 00 for signatures. One can check that the keys are indeed NIST B 233 keys using openssls EC_KEY_check_key function (code forthcoming).

Interesting

[Qmark]

Here's a silly question: why encrypt saves?

[DPyro]

So you can't hack them and create exploits ;)

[bmemike]

Here's a silly question: why encrypt saves?

Probably so you can't spread them around multiple systems. I'm assuming that they're encrypted with data that links them to the actual system that they were saved on. This means you can't just hex edit the file and change "your Wii console ID" to someone else's and play that stuff on someone else's machine.

Same applies for VC content - it's linked to your Wii and encrypted.

If they can find a way to decrypt the content or sign external code, then we'll be VERY close to homebrew for the Wii (possibly without modchips).