OTP Registers
This region (0x10012000-0x10012100) is used as persistent storage on SoC and for passing the TWL console ID around (0x10012100-0x10012108).
Overview
Console-unique keys are derived from here. Access to this region is disabled once the ARM9 writes 0x2 to REG_SYSPROT9.
This is the console-unique data store, including CTCert etc, that ends up in ITCM at 0x01FFB800. After decryption, the first 0x90-bytes of plaintext are copied to 0x01FFB800 if hash verification passes. Refer to Memory_layout#ARM9_ITCM for what is contained in the decrypted OTP.
On FIRM versions prior to 3.0.0-X, this region was left unprotected. On versions since 3.0.0-X, this has been fixed, and the region disable is now done by Kernel9 after doing console-unique TWL keyinit, by setting bit 1 of REG_SYSPROT9. However, with the New_3DS FIRM ARM9 binary this is now done in the FIRM ARM9 binary loader, which also uses the 0x10012000 region for New 3DS key generation.
On development units (UNITINFO != 0) ARM9 uses the first 8-bytes from 0x10012000 for the TWL Console ID. This region doesn't seem to be used by NATIVE_FIRM on retail at all, besides New3DS key-generation in the ARM9-loader.
Normally Boot9 will pass plaintext_otp+0x90 to the AES keyinit function, but when hash verification fails it will pass 0x10012000(otp+0) instead.
Sections
| Offset | Size | Description |
|---|---|---|
| 0x0 | 0x100 | Console-unique data encrypted with AES-CBC. The normalkey and IV are stored in Boot9(retail/devunit have seperate normalkey+IV for this). The last 0x20-bytes of plaintext are a SHA256 hash over the first 0xE0-bytes of plaintext. |
| 0x100 | 0x8 | Before writing REG_SYSPROT9 bit1, the ARM9 copies the 8-byte TWL Console ID here. This sets the registers at 0x4004D00 for ARM7. |
Plaintext OTP
| Offset | Size | Description |
|---|---|---|
| 0x0 | 0x90 | Copied into ITCM. The encrypted version of this is what New3DS-arm9loader hashes for key-generation. |
| 0x0 | 0x4 | This is always 0xDEADB00F. |
| 0x4 | 0x4 | This is the u32 DeviceId. |
| 0x8 | 0x10 | This is the fall-back keyY used for movable.sed keyY when movable.sed doesn't exist in NAND(the last two words here are used on retail for generating console-unique TWL keydata/etc). This is also used for "LocalFriendCodeSeed", etc. |
| 0x18 | 0x1 | ? |
| 0x19 | 0x1 | This is the CTCert issuer type: 0 = retail "Nintendo CA - G3_NintendoCTR2prod", non-zero = dev "Nintendo CA - G3_NintendoCTR2dev". |
| 0x1A | 0x6 | ? |
| 0x20 | 0x4 | This is the CTCert ECDSA exponent, this is byte-swapped when plaintext_otp+0x18 is >=5. |
| 0x24 | 0x2 | ? |
| 0x26 | 0x1E | This is the CTCert ECDSA privk. |
| 0x44 | 0x3C | This is the CTCert ECDSA signature. |
| 0x80 | 0x10 | This is all-zero. |
| 0x90 | 0x70 | Used by Boot9 for generating the console-unique AES keyXs. |