Server Verification

This page describes how the server verifies the client in two implementation scenarios:

1. With Sentinel
2. With a custom server

1) Sentinel Verification

When using Sentinel, the widget:

1. Fetches the challenge directly from the Sentinel server
2. Computes the proof of work
3. Automatically submits the solution to Sentinel for verification

During verification, Sentinel performs additional checks to determine whether to accept or reject the request.

In this workflow, your backend must verify the server signature generated by Sentinel using the verifyServerSignature function.

ALTCHA Sentinel verification workflow

2) Custom Server Verification

When implementing your own server without Sentinel:

1. The widget fetches the challenge from your backend
2. Computes the proof of work
3. Submits the solution payload along with form data to your backend

In this workflow, your backend verifies the challenge solution directly using the verifySolution function.

ALTCHA custom server verification workflow