Difference between revisions of "CXI"
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The following text tries to document the structure of the CTR Executable Image (CXI) format. | The following text tries to document the structure of the CTR Executable Image (CXI) format. |
Latest revision as of 18:59, 18 July 2012
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The following text tries to document the structure of the CTR Executable Image (CXI) format.
Overview[edit]
The CXI format is a specialization of an NCCH container. Generally the CXI will contain executable code, which runs on a single ARM11 core. It can communicate through SVC calls with the other ARM11 core running the 'system' program code. For reasons of clarity, the ARM11 cores will sometimes be called the 'appcore' and 'syscore' respectively.
The CXI format is structured in the following order:
- first a NCCH header,
- followed by an extended header,
- followed by a plain binary region,
- followed by an embedded executable filesystem (ExeFS) - (contains ARM11 code, Home menu icn/bnr and logo),
- and finally followed by a read-only filesystem (RomFS) - (Used for external file storage).
There are specializations of NCCH containers which are not executable, but are used in conjunction with CXI NCCH files. For instance the DLP Child Container and the Home Menu App Manual. (There is a system update NCCH which follows this format, but is used by the 3DS rather than the Application NCCH, and only works when embedded in the CCI format because the nVer is kept in the header of retail CCI files instead of the application NCCH)
Non-Executable NCCH files are structured in the following order:
- first a NCCH header,
- followed by a read-only filesystem (RomFS)
Non-Executable NCCH file examples(Includes Decrypted RomFS):
The extended header contains additional information regarding access control. The plain binary region is an area specifically stored in plaintext, mostly containing SDK library strings for identification.
The extended header, the ExeFS and the RomFS are encrypted using 128-bit AES CTR.
By default encrypted regions are compressed with an LZ77 variant, then encrypted. The spec allows for both unencrypted and uncompressed regions to exist. System titles expect a fixed system key.
NCCH Header[edit]
OFFSET | SIZE | DESCRIPTION |
---|---|---|
0x000 | 0x100 | RSA-2048 signature of the NCCH header, using SHA-256. |
0x100 | 4 | Magic ID, always 'NCCH' |
0x104 | 4 | Content size, in media units (1 media unit = 0x200 bytes) |
0x108 | 8 | Partition ID |
0x110 | 2 | Maker code |
0x112 | 2 | Version |
0x114 | 4 | Reserved |
0x118 | 8 | Program ID |
0x120 | 1 | Temp flag |
0x121 | 0x2F | Reserved |
0x150 | 0x10 | Product code |
0x160 | 0x20 | Extended header hash |
0x180 | 4 | Extended header size |
0x184 | 4 | Reserved |
0x188 | 8 | Flags: byte[5]-byte[7] indicate content type ( system update, application, manual, ... ) size of media unit ( 512*2^byte[6] ) and encryption. |
0x190 | 4 | Plain region offset, in media units |
0x194 | 4 | Plain region size, in media units |
0x198 | 8 | Reserved |
0x1A0 | 4 | ExeFS offset, in media units |
0x1A4 | 4 | ExeFS size, in media units |
0x1A8 | 4 | ExeFS hash region size, in media units |
0x1AC | 4 | Reserved |
0x1B0 | 4 | RomFS offset, in media units |
0x1B4 | 4 | RomFS size, in media units |
0x1B8 | 4 | RomFS hash region size, in media units |
0x1BC | 4 | Reserved |
0x1C0 | 0x20 | ExeFS superblock hash, over the cleartext ExeFS |
0x1E0 | 0x20 | RomFS superblock hash |
NCCH header example for Lego Starwars III[edit]
Signature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agic: NCCH Content size: 0x1cfef400 Partition id: 0004000000038c00 Maker code: 3436 ("46") Version: 0002 Program id: 0004000000038c00 Temp flag: 00 Product code: CTR-P-ALGP Extended header hash: 0C27E3C1DE7B2AE2D3114F32A4EEBF46 9AFD0CF352C11D4984C2A9F1D2144C63 Extended header size: 00000400 Flags: 0000030100000000 Plain region offset: 0x00004a00 Plain region size: 0x00000200 ExeFS offset: 0x00004c00 ExeFS size: 0x00143800 ExeFS hash region size: 0x00000200 RomFS offset: 0x00148400 RomFS size: 0x1ceab000 RomFS hash region size: 0x00000200 ExeFS Superblock Hash: 130C042615F647C4C63225EA9E67F8A2 7B15246B88FBC7A927257B84977B787B RomFS Superblock Hash: A65BEE1060BB6A6821BBCEC600035B7E 64FB6EACA7F0960CFB1F5A37087728F7 Note: Offsets and sizes in media units have been converted to byte sizes.
Plain region example for Lego Starwars III[edit]
0004a00: 5b 53 44 4b 2b 4e 49 4e 54 45 4e 44 4f 3a 43 54 [SDK+NINTENDO:CT [SDK+NINTENDO:CTR_SDK-0_14_23_200_none] 0004a10: 52 5f 53 44 4b 2d 30 5f 31 34 5f 32 33 5f 32 30 R_SDK-0_14_23_20 0004a20: 30 5f 6e 6f 6e 65 5d 00 5b 53 44 4b 2b 4e 49 4e 0_none].[SDK+NIN [SDK+NINTENDO:Firmware-02_27] 0004a30: 54 45 4e 44 4f 3a 46 69 72 6d 77 61 72 65 2d 30 TENDO:Firmware-0 0004a40: 32 5f 32 37 5d 00 5b 53 44 4b 2b 4d 6f 62 69 63 2_27].[SDK+Mobic [SDK+Mobiclip:Deblocker_1_0_2] 0004a50: 6c 69 70 3a 44 65 62 6c 6f 63 6b 65 72 5f 31 5f lip:Deblocker_1_ 0004a60: 30 5f 32 5d 00 5b 53 44 4b 2b 4d 6f 62 69 63 6c 0_2].[SDK+Mobicl [SDK+Mobiclip:ImaAdpcmDec_1_0_0] 0004a70: 69 70 3a 49 6d 61 41 64 70 63 6d 44 65 63 5f 31 ip:ImaAdpcmDec_1 0004a80: 5f 30 5f 30 5d 00 5b 53 44 4b 2b 4d 6f 62 69 63 _0_0].[SDK+Mobic [SDK+Mobiclip:MobiclipDec_1_0_1] 0004a90: 6c 69 70 3a 4d 6f 62 69 63 6c 69 70 44 65 63 5f lip:MobiclipDec_ 0004aa0: 31 5f 30 5f 31 5d 00 5b 53 44 4b 2b 4d 6f 62 69 1_0_1].[SDK+Mobi [SDK+Mobiclip:MoflexDemuxer_1_0_2] 0004ab0: 63 6c 69 70 3a 4d 6f 66 6c 65 78 44 65 6d 75 78 clip:MoflexDemux 0004ac0: 65 72 5f 31 5f 30 5f 32 5d 00 00 00 00 00 00 00 er_1_0_2]....... 0004ad0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................ 0004ae0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................
A tool for parsing this format is available here
Example dependency list from the extended header[edit]
00850 41 50 54 3A 55 00 00 00 24 68 69 6F 46 49 4F 00 APT:U...$hioFIO. 00860 24 68 6F 73 74 69 6F 30 24 68 6F 73 74 69 6F 31 $hostio0$hostio1 00870 61 63 3A 75 00 00 00 00 62 6F 73 73 3A 55 00 00 ac:u....boss:U.. 00880 63 61 6D 3A 75 00 00 00 63 65 63 64 3A 75 00 00 cam:u...cecd:u.. 00890 63 66 67 3A 75 00 00 00 64 6C 70 3A 46 4B 43 4C cfg:u...dlp:FKCL 008A0 64 6C 70 3A 53 52 56 52 64 73 70 3A 3A 44 53 50 dlp:SRVRdsp::DSP 008B0 66 72 64 3A 75 00 00 00 66 73 3A 55 53 45 52 00 frd:u...fs:USER. 008C0 67 73 70 3A 3A 47 70 75 68 69 64 3A 55 53 45 52 gsp::Gpuhid:USER 008D0 68 74 74 70 3A 43 00 00 6D 69 63 3A 75 00 00 00 http:C..mic:u... 008E0 6E 64 6D 3A 75 00 00 00 6E 65 77 73 3A 75 00 00 ndm:u...news:u.. 008F0 6E 77 6D 3A 3A 55 44 53 70 74 6D 3A 75 00 00 00 nwm::UDSptm:u... 00900 70 78 69 3A 64 65 76 00 73 6F 63 3A 55 00 00 00 pxi:dev.soc:U... 00910 73 73 6C 3A 43 00 00 00 79 32 72 3A 75 00 00 00 ssl:C...y2r:u... 00920 69 72 3A 55 53 45 52 00 6C 64 72 3A 72 6F 00 00 ir:USER.ldr:ro.. 00930 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................ 00940 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................ 00950 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................ 00960 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................ ... ... 009D0 FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF 009E0 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................ 009F0 00 03 00 00 00 00 00 00 00 00 00 00 00 00 00 02 . ............. 00A00 5B 53 44 4B 2B 4E 49 4E 54 45 4E 44 4F 3A 43 54 [SDK+NINTENDO:CT
Extended Header[edit]
NOTE: AFTER DECRYPTION
OFFSET | SIZE | DESCRIPTION |
---|---|---|
0x399 | 1 | Memory type (00 = Base, 01 = Application, 02 = System) |