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Created page with "Present in the firmware package titles (0100000000000819, 010000000000081A, 010000000000081B and 010000000000081C) and installed into eMMC storage's Flash_Filesystem#User_Pa..."
Present in the firmware package titles (0100000000000819, 010000000000081A, 010000000000081B and 010000000000081C) and installed into eMMC storage's [[Flash_Filesystem#User_Partitions|BCPKG2 partitions]], "package2" contains the Switch kernel and the built-in system modules.
= Format =
Package2 is distributed in an already encrypted format. Therefore, it's not additionally encrypted when installed into the flash filesystem.
{| class="wikitable" border="1"
|-
! Offset
! Size
! Description
|-
| 0x0
| 0x100
| RSA-2048 signature
|-
| 0x100
| 0x100
| Encrypted header
|-
| 0x200
| Variable
| Encrypted body
|}
== Encryption ==
Package2's contents are AES-CTR encrypted with a key known only by TrustZone.
The encrypted header's CTR is stored as it's first 0x10 bytes (offset 0x100).
The encrypted body is divided in up to 4 sections, each one with a CTR stored inside the decrypted header.
== Header ==
When decrypted, package2's header is as follows.
{| class="wikitable" border="1"
|-
! Offset
! Size
! Description
|-
| 0x0
| 0x10
| Decrypted header's CTR
|-
| 0x10
| 0x10
| Section 0 CTR
|-
| 0x20
| 0x10
| Section 1 CTR
|-
| 0x30
| 0x10
| Section 2 CTR
|-
| 0x40
| 0x10
| Section 3 CTR
|-
| 0x50
| 0x4
| Magic "PK21"
|-
| 0x54
| 0x4
| Unknown
|-
| 0x58
| 0x4
| Unknown
|-
| 0x5C
| 0x4
| Unknown
|-
| 0x60
| 0x4
| Section 0 size
|-
| 0x64
| 0x4
| Section 1 size
|-
| 0x68
| 0x4
| Section 2 size
|-
| 0x6C
| 0x4
| Section 3 size
|-
| 0x70
| 0x4
| Unknown
|-
| 0x74
| 0x4
| Unknown
|-
| 0x78
| 0x4
| Unknown
|-
| 0x7C
| 0x4
| Unknown
|-
| 0x80
| 0x20
| SHA-256 hash over encrypted section 0
|-
| 0xA0
| 0x20
| SHA-256 hash over encrypted section 1
|-
| 0xC0
| 0x20
| SHA-256 hash over encrypted section 2
|-
| 0xE0
| 0x20
| SHA-256 hash over encrypted section 3
|}
Each section follows each other immediately and is encrypted with the same key used for encrypting the header.
== Section 0 ==
When decrypted, this section contains the plaintext Switch kernel binary.
== Section 1 ==
When decrypted, this section contains the built-in system modules encapsulated in a custom format.
=== INI1 ===
{| class="wikitable" border="1"
|-
! Offset
! Type
! Description
|-
| 0x0
| u32
| Magic "INI1"
|-
| 0x4
| u32
| Size
|-
| 0x8
| u32
| NumberProcesses
|-
| 0xC
| u32
| Zero
|}
==== KIP1 ====
Kernel internal process?
{| class="wikitable" border="1"
|-
! Offset
! Type
! Description
|-
| 0x0
| u32
| Magic "KIP1"
|-
| 0x4
| char[12]
| Name
|-
| 0x10
| u64
| TitleId
|-
| 0x18
| u32
|
|-
| 0x1C
| u32
| Flags / etc. Byte3 bit0-2: compression-enable for each section, when set.
|-
| 0x20
| [[#SectionHeader]][3]
| Sections
|-
| 0x50
| char[0x20]
| Padding
|-
| 0x70
| u64[0x20]
| KernelCaps
|}
===== SectionHeader =====
{| class="wikitable" border="1"
|-
! Offset
! Type
! Description
|-
| 0x0
| u32
| OutOffset
|-
| 0x4
| u32
| DecompressedSize
|-
| 0x8
| u32
| CompressedSize
|-
| 0xC
| u32
|
|}
===== Compression =====
The compression used here is BLZ, with a modified footer since 3ds. The footer is now 0xC bytes instead of 0x8, and has the form u32 compressed_data_len; u32 initial_index; u32 additional_len_when_uncompressed;
== Section 2 ==
This section has a valid CTR and SHA-256 hash (over NULL) stored in the package2's header, but it's size is always 0. Likely reserved for future expansion.
== Section 3 ==
This section is not present (CTR and SHA-256 hash in package2's header are NULL). Likely reserved for future expansion.
= Format =
Package2 is distributed in an already encrypted format. Therefore, it's not additionally encrypted when installed into the flash filesystem.
{| class="wikitable" border="1"
|-
! Offset
! Size
! Description
|-
| 0x0
| 0x100
| RSA-2048 signature
|-
| 0x100
| 0x100
| Encrypted header
|-
| 0x200
| Variable
| Encrypted body
|}
== Encryption ==
Package2's contents are AES-CTR encrypted with a key known only by TrustZone.
The encrypted header's CTR is stored as it's first 0x10 bytes (offset 0x100).
The encrypted body is divided in up to 4 sections, each one with a CTR stored inside the decrypted header.
== Header ==
When decrypted, package2's header is as follows.
{| class="wikitable" border="1"
|-
! Offset
! Size
! Description
|-
| 0x0
| 0x10
| Decrypted header's CTR
|-
| 0x10
| 0x10
| Section 0 CTR
|-
| 0x20
| 0x10
| Section 1 CTR
|-
| 0x30
| 0x10
| Section 2 CTR
|-
| 0x40
| 0x10
| Section 3 CTR
|-
| 0x50
| 0x4
| Magic "PK21"
|-
| 0x54
| 0x4
| Unknown
|-
| 0x58
| 0x4
| Unknown
|-
| 0x5C
| 0x4
| Unknown
|-
| 0x60
| 0x4
| Section 0 size
|-
| 0x64
| 0x4
| Section 1 size
|-
| 0x68
| 0x4
| Section 2 size
|-
| 0x6C
| 0x4
| Section 3 size
|-
| 0x70
| 0x4
| Unknown
|-
| 0x74
| 0x4
| Unknown
|-
| 0x78
| 0x4
| Unknown
|-
| 0x7C
| 0x4
| Unknown
|-
| 0x80
| 0x20
| SHA-256 hash over encrypted section 0
|-
| 0xA0
| 0x20
| SHA-256 hash over encrypted section 1
|-
| 0xC0
| 0x20
| SHA-256 hash over encrypted section 2
|-
| 0xE0
| 0x20
| SHA-256 hash over encrypted section 3
|}
Each section follows each other immediately and is encrypted with the same key used for encrypting the header.
== Section 0 ==
When decrypted, this section contains the plaintext Switch kernel binary.
== Section 1 ==
When decrypted, this section contains the built-in system modules encapsulated in a custom format.
=== INI1 ===
{| class="wikitable" border="1"
|-
! Offset
! Type
! Description
|-
| 0x0
| u32
| Magic "INI1"
|-
| 0x4
| u32
| Size
|-
| 0x8
| u32
| NumberProcesses
|-
| 0xC
| u32
| Zero
|}
==== KIP1 ====
Kernel internal process?
{| class="wikitable" border="1"
|-
! Offset
! Type
! Description
|-
| 0x0
| u32
| Magic "KIP1"
|-
| 0x4
| char[12]
| Name
|-
| 0x10
| u64
| TitleId
|-
| 0x18
| u32
|
|-
| 0x1C
| u32
| Flags / etc. Byte3 bit0-2: compression-enable for each section, when set.
|-
| 0x20
| [[#SectionHeader]][3]
| Sections
|-
| 0x50
| char[0x20]
| Padding
|-
| 0x70
| u64[0x20]
| KernelCaps
|}
===== SectionHeader =====
{| class="wikitable" border="1"
|-
! Offset
! Type
! Description
|-
| 0x0
| u32
| OutOffset
|-
| 0x4
| u32
| DecompressedSize
|-
| 0x8
| u32
| CompressedSize
|-
| 0xC
| u32
|
|}
===== Compression =====
The compression used here is BLZ, with a modified footer since 3ds. The footer is now 0xC bytes instead of 0x8, and has the form u32 compressed_data_len; u32 initial_index; u32 additional_len_when_uncompressed;
== Section 2 ==
This section has a valid CTR and SHA-256 hash (over NULL) stored in the package2's header, but it's size is always 0. Likely reserved for future expansion.
== Section 3 ==
This section is not present (CTR and SHA-256 hash in package2's header are NULL). Likely reserved for future expansion.