How do I generate the correct TOTP with Node with correct Headers and SHA512 hashed Token?

A recent school project I was assigned has a coding challenge we have to complete. The challenge has multiple parts, and the final part is uploading to a private GitHub repo and submitting a completion request by making a POST request under certain conditions.

I have successfully completed the other parts of the challenge and am stuck on submitting the request. The submission has to follow these rules:

Build your solution request

First, construct a JSON string like below:

{

    "github_url": "https://github.com/YOUR_ACCOUNT/GITHUB_REPOSITORY",

    "contact_email": "YOUR_EMAIL"

}

Fill in your email address for YOUR_EMAIL, and the private Github repository with your solution in YOUR_ACCOUNT/GITHUB_REPOSITORY. Then, make an HTTP POST request to the following URL with the JSON string as the body part.

CHALLENGE_URL

Content type

The Content-Type: of the request must be application/json.

Authorization

The URL is protected by HTTP Basic Authentication, which is explained on Chapter 2 of RFC2617, so you have to provide an Authorization: header field in your POST request.

• For the userid of HTTP Basic Authentication, use the same email address you put in the JSON string.
• For the password , provide a 10-digit time-based one time password conforming to RFC6238 TOTP.

Authorization password

For generating the TOTP password, you will need to use the following setup:

• You have to generate a correct TOTP password according to RFC6238
• TOTP's Time Step X is 30 seconds. T0 is 0.
• Use HMAC-SHA-512 for the hash function, instead of the default HMAC-SHA-1.
• Token shared secret is the userid followed by ASCII string value "APICHALLENGE" (not including double quotations).

Shared secret examples

For example, if the userid is "email@example.com", the token shared secret is "email@example.comAPICHALLENGE" (without quotes).

If your POST request succeeds, the server returns HTTP status code 200 .

I have tried to follow this outline very carefully, and testing my work in different ways. However, it seems I can't get it right. We are supposed to make the request from a Node server backend. This is what I have done so far. I created a new npm project with npm init and installed the dependencies you will see in the code below:

const axios = require('axios');const base64 = require('base-64');const utf8 = require('utf8');const { totp } = require('otplib');const reqJSON = {    github_url: GITHUB_URL,    contact_email: MY_EMAIL}const stringData = JSON.stringify(reqJSON);const URL = CHALLENGE_URL;const sharedSecret = reqJSON.contact_email +"APICHALLENGE";totp.options = { digits: 10, algorithm: "sha512" }const myTotp = totp.generate(sharedSecret);const isValid = totp.check(myTotp, sharedSecret);console.log("Token Info:", {myTotp, isValid});const authStringUTF = reqJSON.contact_email +":"+ myTotp;const bytes = utf8.encode(authStringUTF);const encoded = base64.encode(bytes);const createReq = async () =>{    try     {        // set the headers        const config = {            headers: {'Content-Type': 'application/json',"Authorization": "Basic "+ encoded            }        };        console.log("Making req", {URL, reqJSON, config});        const res = await axios.post(URL, stringData, config);        console.log(res.data);    }    catch (err)    {        console.error(err.response.data);    }};createReq();

As far as I understand, I'm not sure where I'm making a mistake. I have tried to be very careful in my understanding of the requirements. I have briefly looked into all of the documents the challenge outlines, and gathered the necessary requirements needed to correctly generate a TOTP under the given conditions.

I have found the npm package otplib can satisfy these requirements with the options I have passed in.

However, my solution is incorrect. When I try to submit my solution, I get the error message, "Invalid token, wrong code". Can someone please help me see what I'm doing wrong?

I really don't want all my hard work to be for nothing, as this was a lengthy project.

Thank you so much in advance for your time and help on this. I am very grateful.