Update README.md

Author: JoneWang

README.md

@@ -1 +1,71 @@
-# F-Parameter-API
+# f API
+
+This API is a necessary step in the NSO account authorization process. There is an Android emulator on imink's server with the NSO client installed in it, and the f-parameters are generated by this client. It is completely free, you just need to tell me what project you use it in.
+
+## Usage
+
+You can use the f API already used in imink.
+
+**URL:** `POST` `https://api.imink.app/f`
+
+**Header:** You must send the correct `User-Agent` to let me know that you are requesting it. I suggest the format is: `{{ Your app name }}/{{ Your app version }}`.
+
+**Body:** `JSON`
+
+* token : `String`, **Required**. Get it from NSO api
+* hash_method : `Number or String`, **Required**. 1 or 2
+* timestamp : `Number or String`, Optional. It is not recommended to use this parameter
+* request_id : `String`, Optional. It is not recommended to use this parameter
+
+NOTE: timestamp and request_id will be generated by the server if not submitted. It is recommended to use the api generated timestamp and request_id. If you try to submit your own timestamp, it may cause the NSO api to return a 9599 error.
+
+**Example:**
+
+```
+curl -X "POST" "https://api.imink.app/f" \
+     -H 'User-Agent: {{ Your app name }}/{{ Your app version }}' \
+     -H 'Content-Type: application/json; charset=utf-8' \
+     -d $'{
+  "token": "{{ token }}"
+  "hash_method": {{ 1 or 2 }},
+}'
+```
+
+**Response:**
+```
+{
+  "request_id": "c6e9d62d-7c05-4c9a-8f1a-b6d799fdd5ff",
+  "timestamp": 1661355877196,
+  "f": "543f7e9c4f3d3b5254a3772d211a8c093888b32991002c353f278bc8766face4b548f1bdaea24c9a58e5012b"
+}
+```
+
+## Deploy your own f API
+
+### Download
+
+I modified the official version of NSO to make a new APK. It is easy to let you create your own f API. you can download the latest version from [Releases](https://github.com/imink-app/f-API/releases).
+
+### How to use
+
+1. Install the APK you downloaded into your Android system and it will show up as the NSO icon.
+2. Launch it.
+
+Now you can access it via `http://ip:9000`. ip needs to be replaced with the ip address of your Android device. The request parameters are exactly the same as `api.imink.app/f`.
+
+Yes, it's that simple!
+
+* You don't need to root your Android.
+* You don't need to connect to a computer.
+
+## How is this APK made
+
+1. Cracking the signature verification of NSO.
+2. Decompile apk to smali code.
+3. Insert HTTP Server code and call libvoip.so to compute the f code in smali code.
+4. Repackage as apk.
+5. Re-sign.
+
+The tools used are: jarsigner, Apktool, Xpatch, Android Studio.
+
+Now here is just a simple description of the steps. More code and actions I will update in the future.