CommonETicket

CommonETicket (for short, cetk) is a format as a ticket used to store an encrypted titlekey (using 128-Bit AES-CBC). This format seems to be identical to DSi/Wii tickets.

Structure

All of the data in the file is represented in Big Endian.

Content

Offset	Size	Description
0x000	0x4	Signature Type
0x004	0x100	Signature
0x104	0x3C	Padding modulo 64
0x140	0x40	Issuer
0x180	0x3C	ECDH data for console-unique eShop tickets.
0x1BC	0x3	Unknown, first u8 is 0x01.
0x1BF	0x10	Encrypted TitleKey
0x1CF	0x1	Unknown
0x1D0	0x8	TicketID
0x1D8	0x4	Ticket consoleID
0x1DC	0x8	TitleID
0x1E4	0x2	Unknown
0x1E6	0x2	Ticket version
0x1E8	0x8	Unused
0x1F0	0x1	Unused
0x1F1	0x1	Ticket common keyY index, usually 0x1 for retail system titles.
0x1F2	0xB2	Unused

The Signature Type is the same const as that in TMD. The certificate chain is located at offset 0x2A4 for tickets from CDN/SOAP, however this cert-chain is removed once the ticket is installed to NAND.

The titlekey is decrypted by using the AES engine with the ticket common-key keyslot where the keyY is one of 6 keyYs loaded via the keyY index stored in the ticket. AES-CBC mode is used where the IV is the big-endian titleID. Note that on a retail unit index0 is a retail keyY, while on a dev-unit index0 is the dev common-key which is a normal-key.(On retail for these keyYs, the hardware key-scrambler is used)

Some facts

• CETK can be fetched through HTTP using the link to default update server, using the title's TMD URL where "cetk" is used instead of "tmd" for the URL. The 3DS NIM module retrieves system tickets via SOAP request GetCommonETicket.