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Line 1: − === Overview ===+ − + − An example .CIA can be downloaded [http://depositfiles.com/files/t93cpkb2g here] Credit: [[User:Jl12|Jl12]]. It includes a .cia file, the result of installation, some screenshots. Also I've decrypted/extracted everything, for those people who can't be bothered using ctrtool ;)+ − + − Development Units, are capable of manually installing CIA files via the [[3DS Development Unit Software#Dev Menu|Dev Menu]]+ + + − === Format === Line 16:
Line 17: − The CIA format is capable of containing more then one CXI in the APP data, the TMD specifies the size of CXI contained in the CIA. Generally it will only contain additional CXIs related to the main App CXI, which can hold the Manual and DLP Child. The CIA format could be interpreted as an installable variant of the [[CCI]] format.+ − − − − This is a 32 bytes long header (8 x uint32). Line 30:
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made the opening sentence make sense
[[Category:File formats]]
[[Category:File formats]]
== Overview ==
CIA stands for '''C'''TR '''I'''mportable '''A'''rchive. This format allows the installation titles to the 3DS. CIA files can compile a CXI for installation to either the SDMC or CTR NAND. CIA files can also compile .SRL files (format for DS(i) executable images) for installation to the TWL NAND of the 3DS.
CIA stands for '''C'''TR '''I'''mportable '''A'''rchive. This format allows the installation of titles to the 3DS. CIA files and titles on [[Title list|Nintendo's CDN]] contain identical data. As a consequence, valid CIA files can be generated from CDN content. This also means CIA files can contain anything that titles on Nintendo's CDN can contain.
Under normal circumstances CIA files are used where downloading a title is impractical or not possible. Such as distributing a [[Download Play]] child, or installing forced Gamecard updates. Those CIA(s) are stored by the titles in question, in an auxiliary [[NCCH#CFA|CFA]] file.
[[Download Play]] utilises the CIA format when transferring titles.(This is also the only known retail implementation of the CIA format)
Development Units, are capable of manually installing CIA files via the [[3DS Development Unit Software#Dev Menu|Dev Menu]].
== Format ==
This is the current version of the CIA format, it was finalised in late 2010. (Older versions of the CIA format can be viewed on the [[Talk:CIA|Talk]] page)
The CIA format has a similar structure to the [http://wiibrew.org/wiki/Wad WAD format].
The CIA format has a similar structure to the [http://wiibrew.org/wiki/Wad WAD format].
The data is aligned in 64 byte blocks (if a content ends at the middle of the block, the next content will begin from a new block).
The data is aligned in 64 byte blocks (if a content ends at the middle of the block, the next content will begin from a new block).
=== CIA Header ===
== CIA Header ==
{| class="wikitable" border="1"
{| class="wikitable" border="1"
| 0x00
| 0x00
| 0x04
| 0x04
| Archive Header Size (=0x2020 bytes) (Starts with 0x80 @ offset 0x0020)
| Archive Header Size (Usually = 0x2020 bytes)
|-
|-
| 0x04
| 0x04
| 0x0C
| 0x0C
| 0x04
| 0x04
| Ticket size
| [[Ticket]] size
|-
|-
| 0x10
| 0x10
| 0x14
| 0x14
| 0x04
| 0x04
| ExeFS/Exheader Excerpt size (0 if no excerpt is present)
| Meta size (0 if no Meta data is present)
|-
|-
| 0x18
| 0x18
| 0x04
| 0x08
| APP file size
| Content size
|-
|-
| 0x1C
| 0x20
| 0x04
| 0x2000
| 0x80000000
| Content Index
|}
|}
* Ticket
* Ticket
* TMD file data
* TMD file data
* APP file data
* Content file data
* ExeFS/ExHeader Excerpt
* Meta file data (Not a necessary component)
The contents (NCCH/SRL) are encrypted using 128-bit AES-CBC. The encryption uses the decrypted titlekey from the [[Ticket#Structure|ticket]], and the content index from the TMD padded with zeros as the IV.
=== Certificate Chain ===
There are three [[Certificates|certificates]] in this chain:
{| class="wikitable" border="1"
|-
! CERTIFICATE
! SIGNATURE TYPE
! RETAIL CERT NAME
! DEBUG CERT NAME
! DESCRIPTION
|-
| CA
| RSA-4096
| CA00000003
| CA00000004
| Used to verify the Ticket/TMD Certificates
|-
| Ticket
| RSA-2048
| XS0000000c
| XS00000009
| Used to verify the Ticket signature
|-
| TMD
| RSA-2048
| CP0000000b
| CP0000000a
| Used to verify the TMD signature
|}
The APP data (CXI/SRL) is encrypted, using 128-bit AES-CBC. The encryption uses the decrypted titlekey of the ticket, and the titleid padded with zeros as the IV. To get the decrypted titlekey, the titlekey stored in the ticket must be decrypted using 128-bit AES-CBC with the 3DS common key, and the same IV as mentioned previously.
The CA certificate is issued by 'Root', the public key for which is stored in NATIVE_FIRM.
== ExeFS/ExHeader Excerpt ==
=== Meta ===
The structure of this excerpt is as follows:
The structure of this data is as follows:
{| class="wikitable" border="1"
{| class="wikitable" border="1"
| 0x00
| 0x00
| 0x180
| 0x180
| Title ID dependency list - From the application's ExHeader
| Title ID dependency list - Taken from the application's [[NCCH#Extended Header|ExHeader]]
|-
|-
| 0x180
| 0x180
| 0x280
| 0x180
| Reserved/Unused
| Reserved
|-
| 0x300
| 0x4
| Core Version
|-
| 0x304
| 0xFC
| Reserved
|-
|-
| 0x400
| 0x400
| 0x36C0
| 0x36C0
| [[SMDH|Icon Data]](.ICN) - From the application's [[ExeFS]]
| [[SMDH|Icon Data]](.ICN) - Taken from the application's [[ExeFS]]
|}
|}
Obviously this section is not present in TWL CIA files.
Obviously this section is not present in TWL CIA files, or any other CIA file which does not contain a [[NCCH#CXI|CXI]].
== Tools ==
* [https://github.com/3dshax/ctr/tree/master/ctrtool ctrtool] - Reading/Extraction of CIA files. This can only decrypt the title-key for development CIAs, since retail CIAs use the [[AES]] hardware key-scrambler for the common-key keyslot.
* [https://github.com/ctrdev/ctrsdk/tree/master/tools/make_cia make_cia] - Generating CIA files. Requires CommonKey and ticket/TMD RSA-2048 private exponents.
* [https://github.com/ctrdev/ctrsdk/tree/master/tools/make_cdn_cia make_cdn_cia] - (CMD)(Windows/Linux) Generates CIA files from CDN Content
* [[makerom]] - Tool which can be used to create NCCH, CCI, and CIA files.
== Title Key Encryption ==
The unencrypted Title Key is used to encrypt the data in a CIA. The encrypted Title Key of a CIA can be found at offset 0x1BF in a CIA's Ticket.
Each Title Key is encrypted with AES-CBC to get the encrypted Title Key.
To encrypt an unencrypted title key, you need:
* Common key (as byte array)
* Title ID (as ulong)
* (and of course the unencrypted title key you want to encrypt) (as byte array)
The title key encryption process starts by converting the ulong (Title ID) into a byte array using by retrieving the bytes of the Title ID using BitConverter.GetBytes().
If the converted bytes (title ID) are in Little Endian, reverse those bytes. (in C# it would be Array.Reverse(byte_array_from_bitconverter))
This process makes the Title Key encryption IV.
Next, after you've gotten your Title Key's IV, you can start your cryptography transformation. Using AESManaged, where:
Key = Common Key
IV = the byte array found in the conversion process above
Mode = CipherMode.CBC
Create the encryptor (AesManaged.CreateEncryptor(key, iv)) where the key and IV are both the same as above.
Then, create a CryptoStream and a MemoryStream. The Crypto stream should start with the arguments (memorystream, aes_transform_from_above, CryptoStreamMode.Write).
Write to the CryptoStream where buffer=unencrypted_titlekey, offset=0, and count=the length of the unencrypted title key.
Use FlushFinalBlock() on the CryptoStream.
Finally, then, the encrypted title key will be available from your memory
stream. (to output the calculated encrypted title key as a byte array, you can use memorystream.ToArray(), for example)
Example function: (C#)
<pre>
public static byte[] EncryptMyTitleKey(byte[] commonKey, byte[] titleKey, ulong titleId)
{
// Make encryption IV
byte[] titleidasbytes = new byte[0x10];
for (int i = 0; i < 0x10; i++)
{
titleidasbytes[i] = 0;
}
byte[] bitBytes = BitConverter.GetBytes(titleId);
if (BitConverter.IsLittleEndian)
{
Array.Reverse(bitBytes);
}
bitBytes.CopyTo(titleidasbytes, 0);
// Encrypt
ICryptoTransform transform = new AesManaged { Key = commonKey, IV = titleidasbytes, Mode = CipherMode.CBC }.CreateEncryptor(commonKey, titleidasbytes);
MemoryStream memstream = new MemoryStream();
CryptoStream cryptostream = new CryptoStream(memstream, transform, CryptoStreamMode.Write);
cryptostream.Write(titleKey, 0, titleKey.Length);
cryptostream.FlushFinalBlock();
return memstream.ToArray();
}
</pre>