Difference between revisions of "Ernie Secure"

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For security reasons, sensitive Ernie commands packets are encrypted with a per-session key. This key is generated and shared at second_loader stage through a '''handshake''' between cMeP and Ernie. SNVS (Secure NVS) is a part of NVS that is XTS encrypted and can only be accessed using Ernie secure command 0xD2. eMMC is also XTS encrypted and is accessed with the same command.
 
For security reasons, sensitive Ernie commands packets are encrypted with a per-session key. This key is generated and shared at second_loader stage through a '''handshake''' between cMeP and Ernie. SNVS (Secure NVS) is a part of NVS that is XTS encrypted and can only be accessed using Ernie secure command 0xD2. eMMC is also XTS encrypted and is accessed with the same command.
 +
 +
See also [[Ernie Firmware]].
  
 
= Ernie Secure Packets =
 
= Ernie Secure Packets =
  
−
Packets sent/received with Ernie command 0xD2 are AES-128-ECB encrypted with the Ernie communication session key (stored in [[Bigmac]] keyslot 0x511).
+
Packets sent/received with Ernie command 0xD2 are AES-128-ECB encrypted with the Ernie communication session key (stored in [[DMAC#Bigmac_Key_Ring|Cmep keyring 0x511]]).
  
−
There is a 4 byte command field, 4 byte counter (from Bigmac keyslot 0x512) that increments per send, 6 bytes of zeros, optional data, and a 2 byte checksum. The checksum is the sum of all previous bytes and then negated.
+
There is a 4 byte command field, 4 byte counter (from Cmep keyring 0x512) that increments per send, 6 bytes of zeros, optional data, and a 2 byte checksum. The checksum is the sum of all previous bytes and then negated.
  
 
<source lang="C">
 
<source lang="C">
−
// 30 02 00 0F (step 2, keyset 0xF)
+
// 30 02 00 0F (step 2, keyset 15)
 
typedef struct ernie_packet_handshake_step_2_data_plain { // size is 0x20
 
typedef struct ernie_packet_handshake_step_2_data_plain { // size is 0x20
−
     char cmep_challenge[8]; // random from Bigmac PRNG
+
     char cmep_challenge[8]; // random from Cmep PRNG
 
     char ernie_challenge[8]; // random from Ernie during step 1
 
     char ernie_challenge[8]; // random from Ernie during step 1
 
     char step2_passphrase[0x10]; // hardcoded
 
     char step2_passphrase[0x10]; // hardcoded
 
} ernie_packet_handshake_step_2_data_plain;
 
} ernie_packet_handshake_step_2_data_plain;
  
−
// 30 04 00 0F (step 4, keyset 0xF)
+
// 30 04 00 0F (step 4, keyset 15)
 
typedef struct ernie_packet_handshake_step_4_data_plain { // size is 0x20
 
typedef struct ernie_packet_handshake_step_4_data_plain { // size is 0x20
 
     char step4_5_passphrase[0x10]; // hardcoded
 
     char step4_5_passphrase[0x10]; // hardcoded
Line 25: Line 27:
 
     char step; // 0-5 for command 0xD0
 
     char step; // 0-5 for command 0xD0
 
     char unk_2; // usually 0, 0x20 (command 0xD2)
 
     char unk_2; // usually 0, 0x20 (command 0xD2)
−
     char keyset; // 6 (SNVS), 0xB (command 0xA0), 0xE (SNVS), 0xF (command 0xD0)
+
     char keyset; // 6 (?SNVS?), 11 (command 0xA0), 14 (SNVS), 15 (command 0xD0)
 
     SceUInt32 unk_4; // zeroed or not
 
     SceUInt32 unk_4; // zeroed or not
−
     char enc_data[0x20]; // AES128ECB with key = Bigmac keyslot 0x511, or with the corresponding Step Key for commands 0xA0 and 0xD0
+
     char enc_data[0x20]; // AES128ECB with key = Cmep keyring 0x511, or with the corresponding Step Key for commands 0xA0 and 0xD0
 
} ernie_secure_packet;
 
} ernie_secure_packet;
 
</source>
 
</source>
Line 35: Line 37:
 
== Command 0xA0 ==
 
== Command 0xA0 ==
  
−
This command uses keyset 0xB and is only seen in second_loader. No data transfer is seen. The Ernie communication session key derived here is actually not used. The hypothesis is that this handshake serves as a checkpoint for Ernie to know that cMeP has successfully decrypted ConsoleId and OpenPsId since in between the handshake each decryption happens. The decryption does not use any data from this handshake.
+
This command uses keyset 11 and is only seen in second_loader. No data transfer is seen. The Ernie communication session key derived here is actually not used. The hypothesis is that this handshake serves as a checkpoint for Ernie to know that cMeP has successfully decrypted ConsoleId and OpenPsId since in between the handshake each decryption happens. The decryption does not use any data from this handshake.
  
 
== Command 0xD0 ==
 
== Command 0xD0 ==
  
−
This command establishes a handshake with keyset 0xF. It is used by updater_service_sm command 0xD0002 as well as second_loader.
+
This command establishes a handshake with keyset 15. It is used by updater_service_sm command 0xD0002 as well as second_loader.
  
 
After handshake:
 
After handshake:
−
* Bigmac keyslot 0x511 is programmed with the Ernie communication session key.
+
* Cmep keyring 0x511 is programmed with the Ernie communication session key.
−
* Bigmac keyslot 0x512 is programmed with a 32 bit random number from Bigmac PRNG.
+
* Cmep keyring 0x512 is programmed with a 32 bit random number from Cmep PRNG.
  
 
== Command 0xD2 ==
 
== Command 0xD2 ==
  
−
Command for SNVS read/write and eMMC read/write.
+
Command for SNVS read/write.
  
 
=== Boot dumps ===
 
=== Boot dumps ===
Line 57: Line 59:
 
cMeP <= Ernie: <code>00 00 20 00 47 D3 65 F4 00 00 00 00 00 00 01 DD C7 AB 57 AD 28 9E 00 93 51 F8 D3 D2 29 2E 78 B6 8C 63 5A 26 7A A9 6B C8 E3 AC F3 3D 61 77 F0 EC</code>
 
cMeP <= Ernie: <code>00 00 20 00 47 D3 65 F4 00 00 00 00 00 00 01 DD C7 AB 57 AD 28 9E 00 93 51 F8 D3 D2 29 2E 78 B6 8C 63 5A 26 7A A9 6B C8 E3 AC F3 3D 61 77 F0 EC</code>
  
−
SNVS sector is decrypted using a bigmac keyslot in 0x502-0x504 and result (Mgmt Data) is written to Bigmac keyslot 0x50B (8 bytes).
+
SNVS sector is decrypted using a Cmep keyring in 0x502-0x504 and result (Mgmt Data) is written to Cmep keyring 0x50B (8 bytes).
  
 
Second transaction (Current firmware version read):
 
Second transaction (Current firmware version read):
Line 65: Line 67:
 
cMeP <= Ernie:  <code>20 00 20 00 48 D3 65 F4 00 00 00 00 00 00 95 AD 79 D1 FE 5E 96 4B 3F 66 7D 47 04 28 05 E9 EB D1 26 86 E2 C1 9B 7B 53 B6 D3 11 76 8F 2D 3F 80 ED</code>
 
cMeP <= Ernie:  <code>20 00 20 00 48 D3 65 F4 00 00 00 00 00 00 95 AD 79 D1 FE 5E 96 4B 3F 66 7D 47 04 28 05 E9 EB D1 26 86 E2 C1 9B 7B 53 B6 D3 11 76 8F 2D 3F 80 ED</code>
  
−
Decrypted is a list of versions, two are read using some information from the MBR. On a default 3.60 retail system, the two offsets used are at 0x4 and 0x8. Those are both checked to be 0x03600000 on 3.60 (hard coded). If they are 0xDEADBEEF, the check is skipped. Additionally, in the decrypted buffer from the previous command (written to Bigmac keysslot 0x50B), if bit 1 at byte offset 0x4 is set, then the version check is skipped. Then, if boot is not resume the version from kernel_boot_loader.self is also checked. Finally slot 0x50E and 0x518 are written with these two version codes.
+
Decrypted is a list of versions, two are read using some information from the MBR. Those are both checked to be 0x03600000 on 3.60 (hard coded). If they are 0xDEADBEEF, the check is skipped. Additionally, in the decrypted buffer from the previous command (written to Cmep keyring 0x50B), if bit 1 at byte offset 0x4 is set, then the version check is skipped. Then, if boot is not resume the version from kernel_boot_loader.self is also checked. Finally slot 0x50E and 0x518 are written with these two version codes.
  
 
= Ernie Secure Handshake =
 
= Ernie Secure Handshake =
Line 95: Line 97:
 
# The following operations are only done with Ernie command 0xD0 as it is the only one that registers the Ernie communication session key, once for all.
 
# The following operations are only done with Ernie command 0xD0 as it is the only one that registers the Ernie communication session key, once for all.
 
# cMeP AES-128-ECB encrypts the same 16 byte challenge buffer using '''Ernie Communication Session Key Master Key'''.
 
# cMeP AES-128-ECB encrypts the same 16 byte challenge buffer using '''Ernie Communication Session Key Master Key'''.
−
# This is the '''Ernie Communication Session Key'''. cMeP registers it into Bigmac keyslot 0x511.
+
# This is the '''Ernie Communication Session Key'''. cMeP registers it into Cmep keyring 0x511.
  
 
== Step 4: cMeP tells Ernie to register the Ernie Communication Session Key ==
 
== Step 4: cMeP tells Ernie to register the Ernie Communication Session Key ==
Line 107: Line 109:
  
 
# cMeP gets a response back from Ernie (header <code>30 05 00 0F 00 00 00 00</code>), decrypts the encrypted data with the '''Ernie communication session key''', and checks that it matches the '''Step 4-5 Passphrase'''.
 
# cMeP gets a response back from Ernie (header <code>30 05 00 0F 00 00 00 00</code>), decrypts the encrypted data with the '''Ernie communication session key''', and checks that it matches the '''Step 4-5 Passphrase'''.
 +
 +
= Ernie Secure Keysets =
 +
 +
{| class="wikitable"
 +
|-
 +
! Keyset !! Usage !! Syscon command !! RPC command
 +
|-
 +
| 0 || start/enter SD boot mode || ?none? || 0x110
 +
|-
 +
| 1 || unlock T2 || ?none? || 0x110
 +
|-
 +
| 4 || Jig || ? by pm_sm ||
 +
|-
 +
| 6 || Jig || ? by pm_sm ||
 +
|-
 +
| 11 || Hello || 0xD2 by second_loader ||
 +
|-
 +
| 12 || Jig || ? by pm_sm ||
 +
|-
 +
| 14 || SNVS/Jig - unlock T8 || 0xD2 by second_loader, ? by pm_sm || 0x110
 +
|-
 +
| 15 || Handshake for boot and Syscon firmware update (derives Ernie communication session key for Cmep keyring 0x511) || 0xD0 by updater_service_sm command 0xD0002 and second_loader ||
 +
|}
  
 
= SNVS =
 
= SNVS =
  
−
Ernie provides raw storage in its EEPROM, named NVS (Non-Volatile Storage). The OS partitions some of this storage for encrypted data. The keys to encrypt/decrypt this data is from slots 0x502-0x504. They are derived by second_loader by encrypting using AES-256-CBC a seed with keyslot 0x216, which is console unique. Consoles with minimum firmware < 0.996 use a set of static keys found in second_loader. Minimum firmware comes from IdStorage SMI leaf.
+
Ernie provides raw storage in its Data Flash memory, named NVS (Non-Volatile Storage) by SCE. The PS Vita OS partitions some of this storage for encrypted data. The keys to encrypt/decrypt these data are from Cmep keyrings 0x502-0x504. They are derived by second_loader by encrypting a seed using AES-256-CBC with Cmep keyring 0x216, which is console unique. Consoles with minimum firmware < 0.996 use a set of static keys found in second_loader. Minimum firmware comes from IdStorage SMI leaf.
 +
 
 +
Sectors where data is written are encrypted with AES-XTS.
 +
 
 +
1 sector is 0x20 bytes.
 +
 
 +
<source lang="C">
 +
typedef struct SceMgmtData { // size is 0x20-bytes. for SNVS sector 0.
 +
SceUInt32 magic;
 +
SceUInt32 version;
 +
SceUInt32 status; // ((status & 1) != 0): manu mode/((status & 2) != 0): sd mode
 +
SceUInt32 flags; // ((flags & 1) == 0): SNVS inited/((flags & 2) == 0): QAF inited
 +
SceUInt8 cmac[0x10];
 +
} SceMgmtData;
 +
</source>
 +
 
 +
{| class="wikitable"
 +
|-
 +
! Sector pos !! nSector !! Comment !! Used by
 +
|-
 +
| 0 || 1 || A special SNVS sector called "Mgmt Data". Embeds SNVS flags and ProductMode. Used for Update, PM and QAF. || "sceSblQafManagerSetFlag" (sub_81001610 on FW 0.990), "SpkgInfoUtilGetSNVSFlagStatus" and "SpkgInfoUtilSetSNVSFlagStatus" (on FW 0.931), setProductMode
 +
|-
 +
| 1 || 1 || System Software version info. || ?SceSblUpdateMgr when updating any component?
 +
|-
 +
| 2 || 1 || Processor version info. (Current System Software version, Syscon version, unknown processor, CP version) || ?SceSblUpdateMgr when updating any component?
 +
|-
 +
| 3 || 2 || Some flags. ||
 +
|-
 +
| 5 || 1 || Active SLB2 sha256. || SceSblUpdateMgr when updating SLB2.
 +
|-
 +
| 6 || 1 || Inactive SLB2 sha256. || SceSblUpdateMgr when updating SLB2.
 +
|-
 +
| 7 || 3 || Unknown sectors. ||
 +
|-
 +
| 0xA || 1 || Battery HW info, Battery FW info, unknown info. || SceSblUpdateMgr when updating Battery IC firmware.
 +
|-
 +
| 0xB || 0xA || Unknown sectors. Filled by 0xDEADBEEF. ||
 +
|-
 +
| 0x15 || 1 || QA Flag Version. 0x10 bytes data + 0x10 bytes AES256CMAC. If not QA Flagged unit, 0xFFed with non XTS encrypted. || "sceSblQafManagerSetQaFlagVersion" on FW 0.940
 +
|-
 +
| 0x16 || 0xA || Unknown. 0xFFed. ||
 +
|}
 +
 
 +
 
 +
[[Category:Syscon]]

Latest revision as of 21:59, 10 January 2024

For security reasons, sensitive Ernie commands packets are encrypted with a per-session key. This key is generated and shared at second_loader stage through a handshake between cMeP and Ernie. SNVS (Secure NVS) is a part of NVS that is XTS encrypted and can only be accessed using Ernie secure command 0xD2. eMMC is also XTS encrypted and is accessed with the same command.

See also Ernie Firmware.

Ernie Secure Packets

Packets sent/received with Ernie command 0xD2 are AES-128-ECB encrypted with the Ernie communication session key (stored in Cmep keyring 0x511).

There is a 4 byte command field, 4 byte counter (from Cmep keyring 0x512) that increments per send, 6 bytes of zeros, optional data, and a 2 byte checksum. The checksum is the sum of all previous bytes and then negated. 

// 30 02 00 0F (step 2, keyset 15)
typedef struct ernie_packet_handshake_step_2_data_plain { // size is 0x20
    char cmep_challenge[8]; // random from Cmep PRNG
    char ernie_challenge[8]; // random from Ernie during step 1
    char step2_passphrase[0x10]; // hardcoded
} ernie_packet_handshake_step_2_data_plain;

// 30 04 00 0F (step 4, keyset 15)
typedef struct ernie_packet_handshake_step_4_data_plain { // size is 0x20
    char step4_5_passphrase[0x10]; // hardcoded
    char padding[0x10];
} ernie_packet_handshake_step_4_data_plain;

typedef struct ernie_secure_packet { // size is 0x28
    char unk_0; // 0x30 for commands 0xA0, 0xD0
    char step; // 0-5 for command 0xD0
    char unk_2; // usually 0, 0x20 (command 0xD2)
    char keyset; // 6 (?SNVS?), 11 (command 0xA0), 14 (SNVS), 15 (command 0xD0)
    SceUInt32 unk_4; // zeroed or not
    char enc_data[0x20]; // AES128ECB with key = Cmep keyring 0x511, or with the corresponding Step Key for commands 0xA0 and 0xD0
} ernie_secure_packet;

Ernie Secure Commands

Command 0xA0

This command uses keyset 11 and is only seen in second_loader. No data transfer is seen. The Ernie communication session key derived here is actually not used. The hypothesis is that this handshake serves as a checkpoint for Ernie to know that cMeP has successfully decrypted ConsoleId and OpenPsId since in between the handshake each decryption happens. The decryption does not use any data from this handshake.

Command 0xD0

This command establishes a handshake with keyset 15. It is used by updater_service_sm command 0xD0002 as well as second_loader.

After handshake:

  • Cmep keyring 0x511 is programmed with the Ernie communication session key.
  • Cmep keyring 0x512 is programmed with a 32 bit random number from Cmep PRNG.

Command 0xD2

Command for SNVS read/write.

Boot dumps

First transaction (Mgmt Data read):

cMeP => Ernie: 00 00 20 00 47 D3 65 F4 00 00 00 00 00 00 6C FD

cMeP <= Ernie: 00 00 20 00 47 D3 65 F4 00 00 00 00 00 00 01 DD C7 AB 57 AD 28 9E 00 93 51 F8 D3 D2 29 2E 78 B6 8C 63 5A 26 7A A9 6B C8 E3 AC F3 3D 61 77 F0 EC

SNVS sector is decrypted using a Cmep keyring in 0x502-0x504 and result (Mgmt Data) is written to Cmep keyring 0x50B (8 bytes).

Second transaction (Current firmware version read):

cMeP => Ernie: 20 00 20 00 48 D3 65 F4 00 00 00 00 00 00 4B FD

cMeP <= Ernie: 20 00 20 00 48 D3 65 F4 00 00 00 00 00 00 95 AD 79 D1 FE 5E 96 4B 3F 66 7D 47 04 28 05 E9 EB D1 26 86 E2 C1 9B 7B 53 B6 D3 11 76 8F 2D 3F 80 ED

Decrypted is a list of versions, two are read using some information from the MBR. Those are both checked to be 0x03600000 on 3.60 (hard coded). If they are 0xDEADBEEF, the check is skipped. Additionally, in the decrypted buffer from the previous command (written to Cmep keyring 0x50B), if bit 1 at byte offset 0x4 is set, then the version check is skipped. Then, if boot is not resume the version from kernel_boot_loader.self is also checked. Finally slot 0x50E and 0x518 are written with these two version codes.

Ernie Secure Handshake

This handshake is used totally or partially by Ernie secure commands 0xA0 and 0xD0.

Step 0: cMeP challenges Ernie

  1. cMeP generates an empty buffer 30 00 00 0F 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 and sends it to Ernie.

Step 1: Ernie returns Ernie Challenge

  1. Ernie returns header 30 01 00 0F 00 00 00 00 + 8 byte Ernie Challenge.

Step 2: cMeP sends cMeP Challenge

  1. cMeP composes a data buffer that is 8 bytes of RNG value, 8 byte Ernie Challenge from step 1, and 16 bytes of Step 2 Passphrase.
  2. cMeP encrypts this data using AES-128-ECB and Step 2 Key.
  3. cMeP appends the header 30 02 00 0F 01 00 00 00 and sends to Ernie.

Step 3: Ernie confirms it has received cMeP Challenge

  1. Ernie returns header 30 03 00 0F 00 00 00 00 and a 0x20 byte encrypted buffer.
  2. cMeP decrypts it with AES-128-ECB and Step 3 Key.
  3. cMeP checks that first 8 byte matches the Ernie Challenge from step 2 and next 8 byte matches the cMeP Challenge generated in step 2. The remaining 16 bytes are zero.

Step 3 bis: cMeP registers the Ernie Communication Session Key

  1. The following operations are only done with Ernie command 0xD0 as it is the only one that registers the Ernie communication session key, once for all.
  2. cMeP AES-128-ECB encrypts the same 16 byte challenge buffer using Ernie Communication Session Key Master Key.
  3. This is the Ernie Communication Session Key. cMeP registers it into Cmep keyring 0x511.

Step 4: cMeP tells Ernie to register the Ernie Communication Session Key

  1. Using the Ernie communication session key, cMeP encrypts a known value, Step 4-5 Passphrase.
  2. cMeP appends the header 30 04 00 0F 00 00 00 00 and sends to Ernie.
  3. Ernie decrypts the received data and checks that the passphrase is valid.
  4. Ernie generates the Ernie Communication Session Key the same way as cMeP and registers it in its memory.

Step 5: cMeP receives Ernie encrypted packet for Ernie Communication Session Key verification

  1. cMeP gets a response back from Ernie (header 30 05 00 0F 00 00 00 00), decrypts the encrypted data with the Ernie communication session key, and checks that it matches the Step 4-5 Passphrase.

Ernie Secure Keysets

Keyset Usage Syscon command RPC command
0 start/enter SD boot mode ?none? 0x110
1 unlock T2 ?none? 0x110
4 Jig ? by pm_sm
6 Jig ? by pm_sm
11 Hello 0xD2 by second_loader
12 Jig ? by pm_sm
14 SNVS/Jig - unlock T8 0xD2 by second_loader, ? by pm_sm 0x110
15 Handshake for boot and Syscon firmware update (derives Ernie communication session key for Cmep keyring 0x511) 0xD0 by updater_service_sm command 0xD0002 and second_loader

SNVS

Ernie provides raw storage in its Data Flash memory, named NVS (Non-Volatile Storage) by SCE. The PS Vita OS partitions some of this storage for encrypted data. The keys to encrypt/decrypt these data are from Cmep keyrings 0x502-0x504. They are derived by second_loader by encrypting a seed using AES-256-CBC with Cmep keyring 0x216, which is console unique. Consoles with minimum firmware < 0.996 use a set of static keys found in second_loader. Minimum firmware comes from IdStorage SMI leaf.

Sectors where data is written are encrypted with AES-XTS.

1 sector is 0x20 bytes. 

typedef struct SceMgmtData { // size is 0x20-bytes. for SNVS sector 0.
	SceUInt32 magic;
	SceUInt32 version;
	SceUInt32 status; // ((status & 1) != 0): manu mode/((status & 2) != 0): sd mode
	SceUInt32 flags; // ((flags & 1) == 0): SNVS inited/((flags & 2) == 0): QAF inited
	SceUInt8 cmac[0x10];
} SceMgmtData;
Sector pos nSector Comment Used by
0 1 A special SNVS sector called "Mgmt Data". Embeds SNVS flags and ProductMode. Used for Update, PM and QAF. "sceSblQafManagerSetFlag" (sub_81001610 on FW 0.990), "SpkgInfoUtilGetSNVSFlagStatus" and "SpkgInfoUtilSetSNVSFlagStatus" (on FW 0.931), setProductMode
1 1 System Software version info. ?SceSblUpdateMgr when updating any component?
2 1 Processor version info. (Current System Software version, Syscon version, unknown processor, CP version) ?SceSblUpdateMgr when updating any component?
3 2 Some flags.
5 1 Active SLB2 sha256. SceSblUpdateMgr when updating SLB2.
6 1 Inactive SLB2 sha256. SceSblUpdateMgr when updating SLB2.
7 3 Unknown sectors.
0xA 1 Battery HW info, Battery FW info, unknown info. SceSblUpdateMgr when updating Battery IC firmware.
0xB 0xA Unknown sectors. Filled by 0xDEADBEEF.
0x15 1 QA Flag Version. 0x10 bytes data + 0x10 bytes AES256CMAC. If not QA Flagged unit, 0xFFed with non XTS encrypted. "sceSblQafManagerSetQaFlagVersion" on FW 0.940
0x16 0xA Unknown. 0xFFed.
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