Hacking Biskey Generation (Downgrade Firmware)

[momocop]

I'm currently in the process of downgrading my Switch from 8.1.0 to 6.0.0.

Following the steps to downgrade using PC: https://switch.homebrew.guide/usingcfw/manualchoiupgrade


I'm at the step for BisKey deriving by using this website: https://www.sdsetup.com/biskeygen

When i load my fuses or Tsec files nothing happens after running the pressing Derive.

I see that shchmue says the fuse file format was changed.

I ran a lockpick_rcm and got bis_keys.

Is bis_key_00 the crypto and bis_key_source the tweak key?


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Got answers to my questions! Thank so much everyone. Please close this thread!

 

[Masamune3210]

If I'm not mistaken the first half of the key is the crypto, and the second half is the tweak. At least, that is how hacmount handles it

 

[hexagonlux]

is it possible to generate bis keys from tsec and sbk? I have a raw nand dump as well as fuse and key backups from a broken switch and would love to retrieve save data from it.

 

[Masamune3210]

Not sure sorry

 

[Sonansune]

lockpick dump doesnt separate crypto and tweak. u need to manually split them.
first 32 digits is crypto, and rest is tweak

 

[Undwiz]

Why downgrade ? Really dang pointless