NWM Services
These NWM services are used for local-WLAN communications, NWM module handles regular wifi APs as well. These services are used for creating/connecting to networks, and for sending/receiving data over the network etc. NWM module uses the wifi SDIO hardware via the IO registers for this.
NWM local-WLAN service "nwm::UDS"
| Command Header | Description |
|---|---|
| 0x001B0302 | Initialize |
NWM infrastructure service "nwm::INF"
| Command Header | Description |
|---|---|
| 0x00070742 | ConnectToAP |
NWM socket service "nwm::SOC"
NWM service "nwm::SAP"
NWM local-WLAN StreetPass service "nwm::CEC"
NWM service "nwm::EXT"
NWM service "nwm::TST"
Local-WLAN
UDS is used for 3DS<>3DS local-WLAN communications, and for 3DS<>Wii U communications. The latter is mainly only used for multi-player in games.
All UDS local-WLAN communications have the CCMP key for data encryption generated via NWM module. The CCMP key passed to nwm::CEC commands(stored in a 0x44-byte input structure) for StreetPass is generated by the CECD module. The input data used with EncryptDecryptAes with keytype1 is a MD5 hash over an input passphrase. This input passphrase is fixed for Download Play, it's unique per local-WLAN protocol. The CTR is a MD5 hash over the below 0x10-byte structure. The output from encrypting that data with AES-CTR is the final CCMP key.
Structure used for generating the CTR
| Offset | Size | Description |
|---|---|---|
| 0x0 | 0x4 | Little-endian local-WLAN communication ID, normally this is the user process' UniqueID from the titleID. For Download Play, this is always 0x2810 on retail. |
| 0x4 | 0x4 | Little-endian u32 networkID, randomly-generated when creating the network. The network SSID used when a client connects to the network is sprintf(out, "%08X", networkID). |
| 0x8 | 0x6 | Host MAC address. |
| 0xE | 0x2 | Little-endian ID, for Download Play this is 0x55. |
UDS Beacons
The UDS host broadcasts a beacon containing at least two Nintendo-vendor tags, normally the data stored in these tags are static. The second tag contains the big-endian u32 networkID, used by the clients when connecting to the host and for the above CCMP key generation. The Nintendo-vendor tag(s) following the first two are unique to the process using UDS, these tags are used for broadcasting metadata regarding the host.