Vantri

How fairness works

Every round is decided by three things: a secret server seed, your client seed, and a nonce that counts your bets. Before you play, we show you a fingerprint (SHA‑256 hash) of the server seed. Because we can’t change the seed without changing that fingerprint, we can’t change results after you’ve bet.

When you choose Reveal seed & start new one in the game’s Fairness panel, we show you the old server seed. You can then recheck any round you played with it below.

The method for keno

  1. Bytes come from HMAC‑SHA256 with the server seed as the key and clientSeed:nonce:round as the message, where round starts at 0 and goes up when more bytes are needed.
  2. The numbers 1–40 are shuffled with a Fisher–Yates shuffle from the end of the list. Each byte is reduced to a position; bytes that would make some positions more likely are skipped.
  3. The last 10 numbers after 10 swaps are the draw.

The method for dice

  1. Bytes come from the same HMAC‑SHA256 with the server seed as the key and clientSeed:nonce:0 as the message.
  2. Four bytes at a time are read as one whole number from 0 to 4,294,967,295. Numbers of 4,294,960,000 or more are skipped, so every roll is equally likely.
  3. The roll is that number’s remainder after dividing by 10,000, so it’s a whole number from 0 to 9,999, shown as 0.00 to 99.99.
  4. Your bet uses the same nonce counter as the other games, so each bet gets its own number.

The method for limbo

  1. The first 4 bytes of HMAC‑SHA256(server seed, clientSeed:nonce:0) are read as one whole number n from 0 to 4,294,967,295.
  2. The result is 99 × 4,294,967,296 ÷ (n + 1), divided by 100 and rounded down to 2 decimals. It’s shown as at least 1.00× and at most 1,000,000×.
  3. This makes the chance of reaching any target T exactly 99 ÷ T percent.

The method for Chicken Cross

  1. For each lane in turn, 4 bytes of HMAC‑SHA256(server seed, clientSeed:nonce:round) are read as a whole number n from 0 to 4,294,967,295.
  2. A car comes in the first lane where n is below the level’s chance × 4,294,967,296: Easy 1 in 25 (4%), Medium 3 in 25 (12%), Hard 5 in 25 (20%), Daredevil 10 in 25 (40%).
  3. That lane is fixed when you bet and stays on our server until the game ends. After k lanes the multiplier is 99% ÷ (chance of a clear lane)k, rounded down to 2 decimals.

The method for Towers

  1. There are 9 floors. Easy has 4 tiles and 1 trap per floor, Medium 3 and 1, Hard 2 and 1, Expert 3 and 2, Master 4 and 3.
  2. Floor by floor, from the bottom, the tiles are shuffled with a Fisher–Yates shuffle from the end, using 4 bytes at a time from HMAC‑SHA256(server seed, clientSeed:nonce:round) and skipping values that would make some tiles more likely. The tiles that end up last are the traps.
  3. The traps are fixed when you bet. After k floors the multiplier is 99% ÷ (chance of a safe tile)k, rounded down to 2 decimals.

The method for mines

  1. The 25 tiles are numbered 1 to 25, left to right and top to bottom.
  2. They’re shuffled with a Fisher–Yates shuffle from the end, using HMAC‑SHA256(server seed, clientSeed:nonce:round), for as many steps as there are mines. Each step reads 4 bytes as a whole number and skips values that would make some tiles more likely.
  3. The tiles that end up in the last places are the mines. They’re fixed the moment you bet, and stay on our server until the game ends, so nobody can see them early.
  4. After k gems, the multiplier is 99% × C(25, k) ÷ C(25 − mines, k), rounded down to 2 decimals and capped at 1,000,000×.

The method for plinko

  1. For each row of pegs, 4 bytes of HMAC‑SHA256(server seed, clientSeed:nonce:round) are read as a whole number n from 0 to 4,294,967,295. Eight rows use one hash; more rows use the next round.
  2. If n ÷ 4,294,967,296 is 0.5 or more, the ball goes right at that row; otherwise it goes left.
  3. The slot it lands in is the number of times it went right, counted from 0 at the far left. The pay table for your risk level and number of rows gives that slot’s multiplier.

The method for blackjack

  1. Blackjack is dealt from a 7‑deck shoe of 364 cards. Before shuffling, card k is k mod 52: 0–12 are spades A to K, 13–25 hearts, 26–38 diamonds and 39–51 clubs.
  2. The shoe is shuffled with a Fisher–Yates shuffle from the end, using HMAC‑SHA256(server seed, clientSeed:nonce:round). Each swap reads 4 bytes as a whole number and skips values that would make some positions more likely.
  3. The nonce is the one in use when the shoe was started. A new shoe is shuffled once 273 cards (75%) have been dealt, or when you change seeds.
  4. Cards are dealt in order from the shoe: your first card, the dealer’s up card, your second card, the dealer’s hidden card, then each card as it’s needed (your hits, doubles and splits first, then the dealer’s draws).
  5. You can’t change seeds while a hand is in play, so the cards still to come can’t be worked out.

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