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 title version, this title version is also stored in the TMD.
0x1E8	0x8	Unused
0x1F0	0x1	Unused
0x1F1	0x1	Ticket common keyY index, usually 0x1 for retail system titles.
0x1F2	0xB2	Unused
0x2A4	0x30	Unknown
0x2D4	0x7C	Unused

The Signature Type is the same const as that in TMD.

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)

Certificate Chain

Tickets retrieved from CDN/SOAP have a certificate chain appended at the end of the file. There are two certificates in this chain:

CERTIFICATE	SIGNATURE TYPE	RETAIL CERT NAME	DEBUG CERT NAME	DESCRIPTION
Ticket	RSA-2048	XS0000000c	XS00000009	Used to verify the Ticket signature
CA	RSA-4096	CA00000003	CA00000004	Used to verify the Ticket Certificate

The CA certificate is issued by 'Root', the public key for which is stored in NATIVE_FIRM.

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.