Analyzing the JavaScript Mechanism of the Google+ Button

Other Questions JavaScript
1

I’m attempting to replicate the Google+ button functionality and have come across a portion of code that transforms the session ID into a certain hash value. The session ID is referred to as SAPISID while the resulting hash is called SAPISIDHASH. Can anyone help identify which section of the code handles this hashing process? I’ve dedicated over six hours to this without any success, and I would greatly appreciate any assistance. For reference, VUOyLIU22fNPz2ko/AbGsxW03_WHoGjaJq is the SAPISID and f17aa630b9b9a105dad437b0fedcafe429f6fca2 is the corresponding SAPISIDHASH. I’ve attempted various hashing methods in PHP, but none seem to work.

2

When dealing with the `SAPISID` and `SAPISIDHASH`, it's important to understand that the hashing process is often tied to both the session ID and specific components of the request, like the time or URL. While the exact method might not be publicly documented by Google, we can examine a typical approach.

For the Google authentication mechanism, the `SAPISIDHASH` is generally a combination of a few parameters, including the `SAPISID`, a timestamp, and a secret key. The typical process follows these steps:

  1. Concatenate the current timestamp, the URL of the request, and the `SAPISID` into a single string.
  2. Compute an HMAC (usually SHA-1 or SHA-256) from this string using a secret key.

Here's an example of what this might look like in JavaScript:

// Example assuming the required modules and environment
const crypto = require('crypto');

function generateSAPISIDHASH(sapisid, currentTimestamp, requestURL) {
    const secretKey = 'your_secret_key'; // Google would use a server-side secret key
    const data = `${currentTimestamp} ${requestURL} ${sapisid}`;
    return crypto.createHmac('sha256', secretKey)
                 .update(data)
                 .digest('hex');
}

const sapisid = 'VUOyLIU22fNPz2ko/AbGsxW03_WHoGjaJq';
const timestamp = Math.floor(new Date().getTime() / 1000);
const url = 'https://your_request_url';

const sapisidHash = generateSAPISIDHASH(sapisid, timestamp, url);
console.log(sapisidHash);

Note that the `your_secret_key` is an example and would be managed by Google, making it impossible to exactly replicate their hashing process without it. However, understanding this mechanism can be helpful in approximating the method or verifying similar techniques.

In instances where you still need to verify or debug the `SAPISIDHASH`, consider reaching out for platform-specific documentation or using browser developer tools to inspect network requests and responses related to Google+ authentication.