Ernie Secure: Difference between revisions
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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. | |||
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 [[DMAC#Bigmac_Key_Ring|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. | |||
<source lang="C"> | |||
// 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; | |||
</source> | |||
= 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: <code>00 00 20 00 47 D3 65 F4 00 00 00 00 00 00 6C FD</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 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: <code>20 00 20 00 48 D3 65 F4 00 00 00 00 00 00 4B FD</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. 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 == | |||
# cMeP generates an empty buffer <code>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</code> and sends it to Ernie. | |||
== | == Step 1: Ernie returns Ernie Challenge == | ||
# Ernie returns header <code>30 01 00 0F 00 00 00 00</code> + 8 byte Ernie Challenge. | |||
== | == Step 2: cMeP sends cMeP Challenge == | ||
# 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'''. | |||
# | # cMeP encrypts this data using AES-128-ECB and '''Step 2 Key'''. | ||
# | # cMeP appends the header <code>30 02 00 0F 01 00 00 00</code> and sends to Ernie. | ||
# | |||
== | == Step 3: Ernie confirms it has received cMeP Challenge == | ||
# Ernie returns header <code>30 03 00 0F 00 00 00 00</code> and a 0x20 byte encrypted buffer. | |||
# cMeP decrypts it with AES-128-ECB and '''Step 3 Key'''. | |||
# | # 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 == | ||
# 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'''. | |||
# 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 == | ||
# Using the Ernie communication session key, cMeP encrypts a known value, '''Step 4-5 Passphrase'''. | |||
# cMeP appends the header <code>30 04 00 0F 00 00 00 00</code> and sends to Ernie. | |||
# Ernie decrypts the received data and checks that the passphrase is valid. | |||
# 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 == | |||
# 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 = | ||
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. | |||
[0] = SLB2 Bank 0 SdkVersion | |||
[1] = SLB2 Bank 1 SdkVersion | |||
| ?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 09:27, 11 August 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
- 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
- Ernie returns header
30 01 00 0F 00 00 00 00
+ 8 byte Ernie Challenge.
Step 2: cMeP sends cMeP Challenge
- 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.
- cMeP encrypts this data using AES-128-ECB and Step 2 Key.
- 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
- Ernie returns header
30 03 00 0F 00 00 00 00
and a 0x20 byte encrypted buffer. - cMeP decrypts it with AES-128-ECB and Step 3 Key.
- 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
- 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.
- 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
- Using the Ernie communication session key, cMeP encrypts a known value, Step 4-5 Passphrase.
- cMeP appends the header
30 04 00 0F 00 00 00 00
and sends to Ernie. - Ernie decrypts the received data and checks that the passphrase is valid.
- 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
- 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.
[0] = SLB2 Bank 0 SdkVersion [1] = SLB2 Bank 1 SdkVersion |
?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. |