Open ctr_makecia32.exe from the leaked SDK in a hex editor, go to 0x6017, in that offset you can find the CIA dev Common key, the key starts with 0x55 and ends with 0x15 0x3B and have the SHA1 of 637422C5B34BAF7206AE1B86B556C390DB8EEDB1.Could those keys be used to decrypt the CIAs from the SDK? I wonder how I would go about doing that. Of coarse googling has yet to find the dev keys.
To decrypt the dev .CIA, use ctrtool, here is how: ctrtool --commonkey=*insert commonkey here* --contents=out *insert cia name here*
But this is useless, since the .csu and the .cia shares the same CXI.
Also, you can't decrypt DevMenu and Config, the key will give you the CXI, but the CXI uses some weird crypto that uses some devunit keyslot.