SpotPass

SpotPass is a Nintendo 3DS feature that allows the 3DS to automatically download content, notifications, and software when it's in standby mode.(SpotPass may download/upload some content while the 3DS is in "active" mode, but *only* if the currently active app uses SpotPass) SpotPass can upload content as well. Software downloaded with SpotPass is stored on SD card.

SpotPass Internet communications are mostly HTTPS transfers.

In System Settings, you can disable SpotPass automatic title downloading, but it states that important software will still downloaded.(This only disables downloading of free titles via SpotPass)

'nasc.nintendowifi.net' confirmed usages:(not SpotPass related)

• Friends List applet requires this server to be 'Online' (most likely the reason for regular requests to this server)
• Required for initialization of eShop, (for first time eShop users). Not required for using eShop after first use.

nppl.c.app.nintendowifi.net is used by SpotPass itself to download various data via HTTPS, including a cleartext xml policylist which is country-code specific. This policylist seems to contain a list of SpotPass tasks for certain titles. This policylist can control whether the specified tasks are processed at all.

Homemenu SpotPass usage

See Home Menu.

Automatic System Update Download

With the 2.0.0-2 update, system updates are automatically downloaded via the NIM module. Home Menu uses AM to install the already-downloaded update. It only downloads updates, it will not install updates without the user's permission. See this: http://www.nintendo.com/consumer/systems/3ds/en_na/menu_update.jsp

The system downloads/checks for updates every 24 hours. This is identical to the system used for manual system updates: when it's time to check for updates, it will send a system update SOAP request to the server. When there's an update available, it will then do the usual sysupdate procedure like manual sysupdates.

Content Container

All SpotPass content uses this container to encrypt the payload and sign it. The cleartext content is stored in extdata. The format of these headers is big-endian.

BOSS Header

Offset	Length
0x0	0x4	Magic Number "boss"
0x4	0x4	Magic Number 0x10001
0x8	0x4	Big-endian filesize
0xC	0x8	u64 release date (UNIX timestamp)
0x14	0x2	Must always be 0x1
0x16	0x2	Padding
0x18	0x2	Content header hash type, always 0x2 for SHA-256
0x1A	0x2	Content header RSA size, always 0x2 for RSA-2048 (X<<7)
0x1C	0xC	First 12 bytes of the CTR

Data following the BOSS header is encrypted with AES-CTR. The first 12 bytes of the CTR are from offset 0x1C of the header, while the last word of the CTR in big-endian is 0x1. The CTR from the header is random per file, and an unique random CTR is used each time the content is updated. The cleartext data begins with the content header.

Content Header

Offset	Length	Description
0x0	0x10	?
0x10	0x2	FileID used for the extdata filename
0x12	0x20	SHA-256 hash
0x32	0x100	RSA-2048 signature over the above hash

The first 0x10-bytes are all-zero except the first byte which is 0x80. It's unknown what the first 0x10-bytes are used for.

The hash at offset 0x12 hashes the 0x12-byte data at offset 0x0 followed by a zero u16. The RSA signature is signed by Nintendo. Following this header is the actual content payload, which is written to a cleartext file under the extdata /boss directory. The data following the payload header is written to extdata, but it's unknown what data is written to the extdata file before the content payload.

Payload Content Header

Offset	Length	Description
0x0	0x8	ProgramID
0x8	0x4	Usually zero?
0xC	0x4	Usually 0x10001?
0x10	0x4	Size of the payload after this header
0x14	0x4	Extdata FileID
0x18	0x4	?
0x1C	0x20	SHA-256 hash, unknown what this hashes
0x3C	0x100	RSA-2048 signature over the previous SHA-256 hash

This signature is signed by Nintendo with the same key-pair as the content header.