This decrypts projects from the cocrea.world projects API. Claude and I reverse engineered the website to figure out how this works, then Claude took our learnings and made a script.

gandi-decrypt.js

// how to break the decryption
const https = require('https');
const crypto = require('crypto');

const PROJECT_URL = 'https://www.cocrea.world/@RedLzer2048/SprunkiHyperShifted';

function fetch(url) {
  return new Promise((resolve, reject) => {
    https.get(url, { headers: { 'User-Agent': 'Mozilla/5.0' } }, res => {
      if (res.statusCode >= 300 && res.statusCode < 400 && res.headers.location) {
        return fetch(res.headers.location).then(resolve, reject);
      }
      const chunks = [];
      res.on('data', c => chunks.push(c));
      res.on('end', () => resolve(Buffer.concat(chunks)));
      res.on('error', reject);
    }).on('error', reject);
  });
}

function decrypt(base64Data, assetId) {
  const secret = 'KzdnFCBRvq3';
  const keyBuf = Buffer.from(secret + assetId, 'base64');
  const key = keyBuf.slice(0, 32);
  const iv = keyBuf.slice(0, 16);

  const ciphertext = Buffer.from(base64Data, 'base64');
  const decipher = crypto.createDecipheriv('aes-256-cbc', key, iv);
  const decrypted = Buffer.concat([decipher.update(ciphertext), decipher.final()]);

  // Decrypted text is comma-separated byte values
  return Buffer.from(decrypted.toString('utf-8').split(',').map(Number));
}

(async () => {
  // Step 1: Fetch the page and extract projectLink from __NEXT_DATA__
  console.log('Fetching page...');
  const html = (await fetch(PROJECT_URL)).toString('utf-8');
  const nextData = JSON.parse(html.match(/<script id="__NEXT_DATA__"[^>]*>(.*?)<\/script>/)[1]);
  const projectLink = nextData.props.pageProps.creationData.creationReleaseResp.projectLink;
  console.log('Project link:', projectLink);

  // Step 2: Extract assetId from the URL (the filename without .sb3)
  const assetId = projectLink.match(/\/([a-f0-9]+)\.sb3/)[1];
  console.log('Asset ID:', assetId);

  // Step 3: Download and decrypt
  console.log('Downloading encrypted sb3...');
  const encrypted = await fetch(projectLink);
  const first8 = Array.from(encrypted.slice(0, 8));

  let sb3;
  if (first8[0] === 80 && first8[1] === 75) {
    // Already a valid zip
    sb3 = encrypted;
  } else {
    console.log('Decrypting...');
    sb3 = decrypt(encrypted.toString('utf-8'), assetId);
  }

  console.log('Decrypted:', sb3.length, 'bytes, starts with', Array.from(sb3.slice(0, 4)));

  const fs = require('fs');
  fs.writeFileSync('/tmp/project.sb3', sb3);
  console.log('Wrote /tmp/project.sb3');
})();

gandi-download.js

// paste this into your JavaScript console to download the project as an sb3 (project must already be loaded)
function getVM() {
  const root = document.querySelector('#__next');
  const key = Object.keys(root).find(k => k.startsWith('__reactContainer$') || k.startsWith('__reactFiber$'));
  function search(obj, d) {
    if (!obj || typeof obj !== 'object' || d > 5) return;
    const seen = new WeakSet();
    const stack = [{ o: obj, d }];
    while (stack.length) {
      const { o, d } = stack.pop();
      if (!o || typeof o !== 'object' || d > 5 || seen.has(o)) continue;
      seen.add(o);
      if (typeof o.start === 'function' && typeof o.greenFlag === 'function') return o;
      for (const k of Object.keys(o)) {
        try { if (o[k] && typeof o[k] === 'object') stack.push({ o: o[k], d: d + 1 }); } catch(e) {}
      }
    }
  }
  const fiberSeen = new WeakSet();
  function walk(node, depth) {
    if (!node || depth > 100 || fiberSeen.has(node)) return;
    fiberSeen.add(node);
    for (const k of ['memoizedProps', 'memoizedState'])
      { const r = search(node[k], 0); if (r) return r; }
    if (node.stateNode && typeof node.stateNode === 'object')
      for (const k of ['props', 'state'])
        { const r = search(node.stateNode[k], 0); if (r) return r; }
    return walk(node.child, depth + 1) || walk(node.sibling, depth + 1);
  }
  return walk(root[key], 0);
}

const vm = getVM();
vm.saveProjectSb3().then(blob => {
  const url = URL.createObjectURL(blob);
  const a = document.createElement('a');
  a.href = url;
  a.download = document.title.replace(/[^a-zA-Z0-9 ]/g, '').trim() + '.sb3';
  a.click();
  URL.revokeObjectURL(url);
  console.log('Download started:', a.download, (blob.size / 1024 / 1024).toFixed(1) + ' MB');
});