DSiWare Exports

From 3dbrew
Jump to navigation Jump to search

The DSiWare exported from a 3DS is located at "sdmc:/Nintendo 3DS/<ID0>/<ID1>/Nintendo DSiWare". Filenames are same format as DSi: "<TitleID-Low>.bin". The below sizes include the 0x20-byte block metadata.

DSiWare exported from 3DS use console-unique keyslots initialized by movable.sed. Each section is encrypted with AES-CBC.

The content sections are ordered the same way as DSi: TMD, SRL from content0, <content1-7 for format v2>, public.sav, and banner.sav when banner.sav exists. When the DSiWare export type is 7-11, the 12th content section is the private.sav, if it exists.(ContentX here is the .app data from TWL-NAND /title)

DSiWare Export Types

Value Format version Description
0-6 Same as value 14.
7-11 v2 12 content sections
12 v2 4 content sections
13 v1 4 content sections
14 v2 11 content sections

For NATIVE_FIRM versions where this DSiWare export type field is unused, format version v1 is used with 4 content sections. Otherwise when this field is used, see the above table. System Settings uses type 1, regardless of the System Settings title-version.

Block Metadata

Offset Size Description
0x0 0x10 AES MAC over a SHA-256 hash
0x10 0x10 IV, generated by the RNG.

Each section begins with the payload encrypted data, followed by this block metadata. The SHA-256 hash used for the MAC is calculated over the cleartext payload. This hash used for generating the MAC is also stored in the footer.

Footer

Offset Size Description
0x0 X SHA-256 hashes over the banner, header, and content sections. When a content section doesn't exist, the corresponding hash here is uninitialized.
0x0 + X 0x3C ECDSA signature over the previous hashes, signed by the APCert.
0x3C + X 0x180 ECDSA "APXXXXXXXXXXXXXXXX" cert signed by the below CTCert, where X is random lowercase ASCII hex data.
0x1BC + X 0x180 ECDSA CTCert
0x33C + X 0x4 Uninitialized padding.

These hashes are the same hashes used for generating each section's MAC stored in the metadata block. X = 0x40 + totalcontentsections*0x20.

File Structure v1

Offset Size Description
0x0 0x4020 Banner section
0x4020 0xC0 Header section
0x40E0 0x340 + 0x20 + X, where X is the total size of the hashes stored in the footer. Footer section
0x40E0 + footer_size Content sections

Header

Offset Size Description
0x0 0x4 Magic number 0x54444633, "3FDT".
0x4 0x2 Byte-swapped groupID from the TWL TMD.
0x6 0x2 Byte-swapped title version from the TWL TMD.
0x8 0x20 SHA-256 hash calculated over the encrypted movable.sed.
0x28 0x10 Encrypted AES block from encrypting an all-zero 0x10-byte block with AES-CBC, where the IV is all-zero.
0x38 0x8 Byte-swapped titleID from the TWL TMD.
0x40 0x8 ?
0x48 0x10 u32 payload sizes for the 4 content sections.
0x58 0x4 ?
0x5C 0x3E Data from the TWL TMD reserved section. Only the first 0x20-bytes from the TWL TMD is written here, the rest is uninitialized.
0x9A 0x6 Padding?

File Structure v2

Offset Size Description
0x0 0x4020 Banner section
0x4020 0x110 Header section
0x4130 0x340 + 0x20 + X, where X is the total size of the hashes stored in the footer. Footer section
0x4130 + footer_size Content sections

Header

Offset Size Description
0x0 0x4 Magic number 0x54444633, "3FDT".
0x4 0x2 Byte-swapped groupID from the TWL TMD.
0x6 0x2 Byte-swapped title version from the TWL TMD.
0x8 0x20 SHA-256 hash calculated over the encrypted movable.sed.
0x28 0x10 Encrypted AES block from encrypting an all-zero 0x10-byte block with AES-CBC, where the IV is all-zero.
0x38 0x8 Byte-swapped titleID from the TWL TMD.
0x40 0x8 ?
0x48 0x2C u32 payload sizes for the 11 content sections.
0x74 0x30 ?
0xA4 0x3E Data from the TWL TMD reserved section. Only the first 0x20-bytes from the TWL TMD is written here, the rest is uninitialized.
0xE2 0x0E Padding?