SReverseby Simpa Labs

Capabilities · Authentication

Reproduce the login, session and token machinery.

Authentication is a sequence, not a single request. We trace the steps from first launch to a valid session, then rebuild the sequence so your client is seen the same way.

Credential flow Device registration Token generation Refresh tokens OAuth
trace · login
POST /auth/device      install id + device key
POST /oauth/token      grant_type + proof
access_token:  eyJhb...K3A
refresh_token: r2f0...91c
GET  /me  (access token)
A session is state

You hold the token, the refresh token, and any server-side state the app created. Reproducing one without the rest fails.

The pieces

What an auth flow carries

Credential flow

How the app sends the password or proof, and whether it wraps the call in extra values.

Device registration

A first call that records the install, derives an identifier, and binds the token to it.

Token generation

What the app sends to earn an access token, and how long that token stays valid.

Refresh

The call that trades a refresh token for a new access token once the old one expires.

OAuth

Grant type, client id, scope and PKCE. Those parameters are part of the request.

Nonce and timestamp

Fresh values the app adds to a call, which a reproduction must generate on each attempt.

Session state

State you may have to recreate

An endpoint can reject a valid token because the session it belongs to does not exist. We map what the server remembers so the client can offer it.

  • Cookies set during login
  • Device-bound identifiers
  • Server-side session records
  • Scope granted to the token
  • Tokens cached by the app
  • Time-based validity
  • A per-session secret
  • Proof-of-possession checks

Binding

Auth is often device or secret bound

01

Derive the device value

Read the identifier the app builds, and the key it signs it with.

02

Replay registration

Perform the registration call so the server creates the session your token belongs to.

03

Hold the secret

Keep whatever value signs or proves the session, and refresh it when the server asks.

The point

Valid credentials can fail if the device or secret binding is missing. Reproduce the binding along with the token.

Reproduce it

Rebuild the sequence, not the screenshot

auth_flow.py
# OAuth refresh example; configure the app's token endpoint and client auth.
import requests

def refresh(token_url, refresh_token, client_id):
    response = requests.post(
        token_url,
        data={"grant_type": "refresh_token",
              "refresh_token": refresh_token,
              "client_id": client_id},
        timeout=30,
    )
    response.raise_for_status()
    tokens = response.json()
    access_token = tokens["access_token"]
    next_refresh = tokens.get("refresh_token", refresh_token)
    return access_token, next_refresh

OAuth refresh example. Use the token endpoint and client authentication required by the service. RFC 6749, section 6.

Where the flow needs a nonce, a timestamp, or a signature over the token request, those steps sit inside the sequence. We fold them in, so the reproduction keeps working past the first call.

Send us the app

Need a session that holds?

We rebuild the login, registration and token flow so your client gets a valid session.

Projects start at $120. Most are delivered in 24 to 72 hours.

One full APK. One complete delivery.

Projects start at $120. Most are delivered in 24 to 72 hours.

Every format included

Python, JavaScript/TypeScript, Postman and complete API documentation cover the same full endpoint set. Your team runs the clients in its own server or system.

Ready in 24–72 hours

The delivery window starts after we receive the APK and any account access needed to run it. The fixed quote states the deadline. Most projects finish sooner.

Deployment checked before the quote

The package includes signing, encryption, decryption and session handling. We verify device-bound keys and server integrity checks during review and document runtime requirements before you commit.

30 days of fixes

Report a defect within 30 days of delivery. We fix any delivered call that does not match the tested APK at no extra cost.

Start your full APK reconstruction

Send the full APK

Projects start at $120. Choose WhatsApp or email, then attach the APK in the app that opens. We reply within one hour with the next step and send the fixed quote after review.

Want us to contact you?