The DSiWare exported from a 3DS is located at
“
sdmc:/Nintendo 3DS/
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,
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 for exporting DSiWare, 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.
| 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 using SHA-256 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.
The curve sect233r1 is used for all related ECDSA signing operations
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? |