cyberbrawl-bracket-seeding

This repository contains the official bracket seeding algorithm for CyberBrawl.io tournaments. The goal is to provide a deterministic and transparent way to shuffle and seed players in CyberBrawl's competitive events.

How It Works

When creating tournament brackets for CyberBrawl.io, we follow this transparent process:

• A unique salt is generated, and its SHA-256 hash is published at the time of the tournament announcement.
• Once player registrations are finalized, a seed is created by combining the player IDs, respecting enlistment order, with the salt.
• Players are shuffled using the deterministic Fisher-Yates shuffle algorithm.
• If the total number of players is not a power of 2, "BYE" slots are added as placeholders to complete the bracket.
• Initial matches are then determined by systematically pairing players from the two halves of the shuffled list.

This simple process ensures that the brackets are randomized, fair, and resistant to manipulation from both players and organizers.

Process Breakdown

1. Input:

   • players: list of player IDs.
   • salt: predefined unique string.

2. Steps:

   1. Computing the seed:
      • Concatenate all players IDs into a string.
      • Append salt to the concatenated string.
      • Generate a SHA-256 hash of the combined string.
      • Extract the first 4 bytes of the hash and convert them to integer (big-endian).
   2. Shuffling the players:
      • Use the Fisher-Yates shuffle algorithm.
      • Seed the RNG with the computed seed.
   3. Padding the shuffled players:
      • If the number of players is not a power of 2, pad the shuffled players list with bye until the total length matches the nearest power of 2.
   4. Pairing the shuffled players:
      • Pair players from the two halves of the shuffled list.

Example Code

  const seedBracket = (players, salt) => {
      const padded = [...players];
      const seed = parseInt(crypto.createHash('sha256').update(padded.join('') + salt).digest('hex').slice(0, 8), 16);
      const shuffle = (array, seed) => {
          const rng = ((s) => () => (s = (s * 9301 + 49297) % 233280) / 233280)(seed);
          for (let i = array.length - 1; i > 0; i--) {
              const j = Math.floor(rng() * (i + 1));
              [array[i], array[j]] = [array[j], array[i]];
          }
          return [
              ...array,
              ...Array((2 ** Math.ceil(Math.log2(players.length))) - players.length).fill('bye')
          ];
      };
      const shuffled = shuffle(padded, seed);
      return { seed, matches: Array.from({ length: shuffled.length / 2 }, (_, i) => [shuffled[i], shuffled[shuffled.length / 2 + i]]) };
  };

Run it in CodeSandbox:

Official Cyberbrawl Tournaments

Here is a record of salts and players data used for seeding official tournaments. You can verify the seeding process against these values:

Beta Launch Tournament

{
    "players": [ "gonz0", "9x1r1s", "ihgux3", "2jw8kp", "vqnl28", "j52nl0", "kside", "q0vbp1", "m268p0", "master", "fo2xo6", "energy", "xqcaax", "garden", "zero", "joegkl",     
"jdtgw9", "sqcleg", "y2g1mv", "3oblfz", "eesphk", "zkneug", "641m9e", "os1ugx", "dragon", "i7ge2a", "vuhyms", "q8yoqn", "6pqirj","kunkun","hwamni"],
    "salt": "b3d10071-a0f1-e368-abc0-74db4a61b028",
    "hash": "6d1451adda4f44d3a1a27118388ea34db5c6c8316141378bd9467d4d64644c3e",
}

License

MIT License