Cmep registers

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Key slots


   Initial state: Empty keyslots.
   0x000-0x007: Empty group0 slave keyslots, for AES decryption only.
   0x008-0x00F: Empty group1 slave keyslots, any algo.
   0x010-0x01F: Empty group2 slave keyslots, for AES decryption only.
   0x020-0x02F: Empty group3 slave keyslots, any algo.
   0x030-0x07F: Empty normal keyslots, any algo.


   Initial state: Empty keyslots.
   0x100-0x17F: Empty normal keyslots, any algo.


   Initial state: Filled in, key material.
   0x200-0x203: AES decryption-only keys (for memory buffers).
   0x204-0x205: Master keys (for group0), any algo.
   0x206-0x20D: Master keys (for group1), any algo.
   0x20E-0x20F: Emmc keys, fully protected.
   0x210-0x217: General purpose keys (for memory buffers).


   Initial state: Filled in, key material.
   0x300-0x33F: AES decryption-only keys (for memory buffers).
   0x340-0x343: Master keys (for group2), any algo.
   0x344-0x353: Master keys (for group3), any algo.
   0x354-0x3FF: General purpose keys (for memory buffers).


   Initial state: Empty data storage, read-write from keyring.


   Initial state: Empty data storage, read-write from keyring.


   Initial state: Filled in data, read-only. Keyring only.
   0x603: u32 BootromFlags.
     Bit0-15: HasRsaRevocationKey. This is set to 0xFFFF.
     Bit16:   UseAlternativeEmmcClock


   Initial state: Filled in data, read-only. Keyring only.
   0x700-0x708: RsaRevocationKey0
   0x708-0x710: RsaRevocationKey1
   0x710-0x718: RsaRevocationKey2
   0x718-0x720: RsaRevocationKey3
   0x720-0x728: RsaRevocationKey4
   0x728-0x730: RsaRevocationKey5
   0x778-0x780: RsaRevocationKey15


E0000000: MailboxFoodToArm

Response to ARM is written here.

E0000010: MailboxArmToFood

Request from ARM is written here.

E0000020: MailboxFoodToDebugger

Size: 2x u32.

E0000028: MailboxDebuggerToFood

Size: 2x u32.

E0000060: MailboxDebuggerToFood2

Size: 2x u32.

E0010000: FootReset

   Bit0: Hangs. ARM uses this to reset the F00D subsystem.

E0010004: FoodStatus

   Bit31:  IsFoodAlive
   Bit0-2: ?
   0xE0010000: 00 00 00 00 05 00 00 80 00 00 00 00 00 00 00 00
   0xE0010010: 01 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00


Reads back 0x7FF. Then hangs after delay.

   Bit5: Disables Key* registers, and KeyRingDirectAccess

No bit appears to disable Rsa* registers, or Bigmac*.

   0xE0020000: 0F 00 02 00 00 00 00 00 00 00 00 00 00 00 00 00
   0xE0020010: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00



   Bit0: Reboot when cleared.
   Bit1: Hang when cleared. Unrecoverable
   Bit2: No hang when cleared.
   Bit3: No hang when cleared.
   Bit16: No hang when cleared.

E0020004: ?

second_loader writes 0x30003 followed by 0 here, after clearing keys.

E0020020: ?

rsa_expmod() reads and writes back this register before reading the result of the RSA operation.

Keyring controller

E0030000: KeySetValue

Size: 8x u32.

E0030020: KeySetValueTrigger

Write keyslot here, and it will write value written above to it.

E0030024: KeySetProtect

   Bit0-15:  KeyslotNumber
   Bit16-31: KeyslotClearFlags

E0030028: KeyQueryProtect

   Bit0-15: KeyslotNumber

E003002C: KeyQueryProtectResult

   Bit0: SlotExists
   Bit1: HasBeenWrittenOnce. You cannot use a key if this is not set.
   Bit2: HasBeenWrittenMoreThanOnce
   Bit16:   Clearable   | AesEncryptAllowed (CTR+CBC+ECB, any key size)
   Bit17:   Clearable   | AesDecryptAllowed (CTR+CBC+ECB, any key size)
   Bit18:   Clearable   | ShaHmacAllowed (SHA1+SHA256)
   Bit19:   Clearable   | AesCmacAllowed
   Bit20:   Clearable   | EmmcCryptoAllowed (qualified guess!)
   Bit21:   Fixed       | IsMaster
   Bit22:   Fixed       | MemberOfGroup0
   Bit23:   Fixed       | MemberOfGroup1
   Bit24:   Fixed       | MemberOfGroup2
   Bit25:   Fixed       | MemberOfGroup3
   Bit26:   Clearable   | SetByBigmacAllowed
   Bit27:   Clearable   | SetByKeyringAllowed
   Bit28:   Clearable   | GetByKeyringAllowed

A master key can only write into a slave keyslot belonging to the same group(s) as itself.

A master key cannot write into a non-slave keyslot or external memory.

Normal keyslots are keyslots that don't belong to any group (bit21-25 are all zeroes). They can be written by slaves of groups, and also by normal non-keyslot operations.

A slave can write output to a normal keyslot or to external memory.

VULN!! If you have AesDecryptAllowed, you can encrypt arbitrary AES blocks without AesEncryptAllowed. Use CTR mode.

SceBignum controller?

Many registers are wrong

E0040108 RsaSignatureBuffer

Size: 0x100 bytes.

E0040400 RsaModulusBuffer

Size: 0x100 bytes.

E0040800 RsaControl

In u32's.

E0040800 RsaStatus

   Bit31: Busy

E0040808 RsaExponent

SceBigmac controller

E0050000 BigmacSrc

E0050004 BigmacDst

E0050008 BigmacSize

E005000C BigmacOp

Unlike Dmac5, DES is not supported for Bigmac.

 Bit0-6: Algorithm
 0x00 = Zeroes?
 0x01 = AesEcbEncrypt
 0x11 = AesCtrEncrypt
 0x21 = AesCtrDecrypt
 0x41  = !!! HANG !!!
 0x61  = !!! HANG !!!
 0x141 = !!! HANG !!!
 0x02 = AesEcbDecrypt
 0x03 = Sha1
 0x13 = Sha256
 0x23 = HmacSha1, keylength=32 bytes
 0x33 = HmacSha256, keylength=32 bytes
 0x43 = <0x03>
 0x53 = <0x13>
 0x04 = Rng
 0x05 = Zeroes
 0x06 = Zeroes
 0x07 = Zeroes
 0x09 = AesCbcEncrypt
 0x0a = AesCbcEncrypt
 0x0b = Sha224
 0x1b = !!! HANG !!!
 0x2b = !!! HANG !!!
 0x3b = AesCmac
 0x4b = <0x0b>
 0x7b = <0x3b>
 0x0c = Zeroes
 0x0d = Zeroes
 0x0e = Zeroes
 0x0f = Zeroes
   Bit7:    UseExternalKey
   Bit8-10: KeySize (0=64bit, 1=128bit, 2=192bit, 3=256bit)
            (Applies only to AesEcb, AesCbc, AesCmac)
   Bit11:   Nothing noticable for AesEcbEncrypt
   Bit12:   Nothing noticable for AesEcbEncrypt
   Bit24:   Causes hang
   Bit25:   Causes hang
   Bit28:   IsDstKeyslot

The following are known to be able to write keyslots:

 * AesEcbEncrypt/Decrypt:
     Size is rounded up to multiple of 4.
     If size > 16, size = 16.
     Read |size| bytes from |src| into HW state.
     The remaining 16-|size| bytes of state *ARE KEPT FROM RESULT OF PREVIOUS AES OPERATION*.
     VULN! This allows key recovery of all slave keyslots during boot.
     The key written to keyslot is always 16 bytes long, padded with 00's.
 * AesCbcEncrypt/Decrypt: Size is rounded up to multiple of 4. 
 * AesCtrEncrypt/Decrypt: Size is rounded up to multiple of 4.
 * AesCmac                Puts the 16 byte hash into keyslot.
                          Bytes 16-31 are *FORCED* 0.
 * Sha1:                  Puts the 20 byte hash into keyslot.
                          Bytes 20-31 are *FORCED* 0.
 * Sha224:                Puts the 28 byte hash into keyslot.
                          Bytes 28-31 are *FORCED* 0.
 * Sha256:                Puts the 32 byte hash into keyslot.
 * HmacSha1               Probably same as Sha1.
 * HmacSha256             Probably same as Sha256.
 * Rng

AesCtrEncrypt when having a keyslot dst, still reads from src.

VULN! Any SHA with length==0 produces an output of all zeroes!

E005001C BigmacTrigger

Writing 1 here starts bigmac operation.

E0050024 BigmacStatus

Set when invalid keyslot (0xFFF).

   Bit18: Set when keyslot is not allowed to perform operation.

E005003C BigmacRng

Reads a random value.

E0050200 BigmacExternalKey

Size: 0x20 bytes

VULN! Allows partial overwrite. However when using keyslot crypto, this key remains unaffected. Thus it cannot be used to recover keyslot keys.

SceBigmac Keyring

E0058000 KeyRingDirectAccess

Size: 0x10000 bytes.


E0070000 EmmcCryptoToggle?

Set to 1.