Awesome

NSO Token Gen

In order to authenticate to Nintendo's web services to use things like SplatNet 2 or NookLink, you need a token that the NSO app generates. It uses a native library to generate these tokens, and unfortunately, the easiest way to generate them on a computer is to use an Android device to access that native library.

This is a Python program that uses Frida to talk to an Android device and generate those tokens using that native library. It also uses aiohttp to run a local web service that you can access from your own programs to obtain those tokens.

Note that due to the way Frida works, you will need a rooted Android device. I did my testing using an Android x86 VM in VirtualBox, as I don't have a physical rooted device, but it should work on either type of device.

Inspired in part by nxapi, which performs a similar function using Frida and an Android device in JS. I spent some time trying out Frida before, and I learned how to call functions within the NSO app, but I didn't have any ideas on how to turn that into a service that programs could use to generate tokens until I saw nxapi's implementation.

If you're using splatnet2statink, with some minimal changes to iksm.py, you can use nsotokengen to generate f tokens as part of the authentication process if you want to generate your tokens locally. See the wiki for instructions on the specific changes to make.
The same goes for s3s, but it's even easier because you just have to change a setting in the config file. Check the wiki for more information.

Setup

The setup process is rather similar to nxapi's setup. You'll need a rooted Android device and a computer with adb to communicate with it. You'll also need to install the Frida server and the NSO app on the rooted device.

Follow these instructions to set up Android x86 as a VM on your computer if you don't have a physical rooted device to use: https://www.android-x86.org/installhowto.html

Then, follow these instructions to install the Frida server on your Android device: https://frida.re/docs/android/
nsotokengen will attempt to start the Frida server with the assumption that you placed it at /data/local/tmp/frida-server as per the Frida docs.

If you don't have adb, you can download it from here: https://developer.android.com/studio/releases/platform-tools
Make sure you add it to your system's PATH variable, as nsotokengen will call it to connect to your Android device.

Rename the config.json.sample file to config.json and set the android_device_ip to the IP address of your Android device. If you're using a port other than 5555 for adb, change android_device_port as well.

The web server will listen on port 8080 by default, and this can be changed through the config file if you have another service running on that port.

Usage

Once you've installed the Python requirements and set up your Android device, you should be ready to run the program.

There are two ways to use nsotokengen. You can run it directly to start the web service and generate tokens by POSTing data to it. Or, you can import nsotokengen into your Python project as a package and call its functions directly.

As a Web Service

Run nsotokengen.py. It will verify that adb is available on the PATH, then it will use it to connect to your Android device, and then it will connect to the Frida server running on it. If anything doesn't work, it'll print an error message that should help you figure out what went wrong.

Sometimes, the Frida server won't start on the Android device, and nsotokengen will raise a frida.ServerNotRunningError exception since it can't connect to it. If this happens, try restarting nsotokengen. It will usually work after a few tries. If it still can't connect, try restarting your Android device.

To test out the web service once it's running, use curl or a similar tool to hit localhost:8080/f. You should get back a 405: Method Not Allowed error. That's just because the endpoint on the web service only responds to POST requests.

I modeled the API after the imink API, as it seemed to use a fairly sensible design. As such, the API expects JSON data to be POSTed to it, and it will respond with JSON data.

You'll need to provide the following keys and values:

Due to changes in how the NSO authentication process works, nsotokengen will now handle generating the timestamp and request ID.

POST a JSON to the API and you'll get a JSON response back. If there's a key named error, something went wrong, and you should check the reason key to figure out what happened. Otherwise, there will be three keys, named f, timestamp, and request_id. Since nsotokengen now generates the timestamp and request ID, those values will be sent in the response, along with the f token, and you'll need to use those values when authenticating to NSO.

As a Package

To use nsotokengen as a package in your Python project, start by importing it:

import nsotokengen

Next, call nsotokengen.setup() to connect to the Android device. It's recommended that you print a message and wait for user confirmation before you call this so that users can start their Android devices and get everything set up first.

nsotokengen.setup()

If anything goes wrong, a RuntimeError will be raised with a description of what happened.

Sometimes, Frida isn't able to connect to the Frida server running on the Android device, even though it's running. nsotokengen will raise a frida.ServerNotRunningError if this occurs. For this reason, you might want to run nsotokengen.setup() a few times in a loop, just to make sure it's able to connect, as the connection issues usually work themselves out if you try to connect a few times.

Once the setup is complete, you can now generate both types of tokens using the following functions:

nsotokengen.gen_audio_h("token_goes_here")
nsotokengen.gen_audio_h2("token_goes_here")

You'll receive a dictionary containing the generated token, the timestamp, and the request ID. Since nsotokengen now generates the timestamp and request ID, you'll need to use the values returned from the functions when authenticating to NSO.

Other Interesting Projects

I got the idea to write this program after seeing nxapi, as it has a similar component that uses Frida to connect to a rooted Android device to generate f tokens. It was written in JS, which is a language I haven't used, so I thought I'd try writing something similar in Python.
nxapi actually does a lot more than just generate those tokens. It provides a way to access the services NSO lets you use on your phone, like SplatNet 2 and NookLink, but right on your computer. You should check it out.

imink is an iOS app that provides an alternate interface to the data SplatNet 2 provides, like your battle results and map schedules. The creator of the app stood up a web service to generate f tokens and was gracious enough to provide public API documentation for its use. If you don't want to set up nxapi or nsotokengen locally, you can use the imink API to generate f tokens for your program.

splatnet2statink is a project I worked on that can download your Splatoon 2 battle logs from SplatNet 2 and upload them to stat.ink to track your battle stats.
s3s is the successor to splatnet2statink that works with SplatNet 3 to track your Splatoon 3 battles.