Fairness protocol v1

Every jackpot winner is decided on the server with cryptographic randomness before the wheel spins. The wheel only replays a result that is already recorded. Before a round takes entries we publish a hash of a secret seed; once the round ends we reveal the seed so anyone can recompute the winner.

Before entries open:
  server_seed      = 32 random bytes (CSPRNG, Postgres pgcrypto)
  server_seed_hash = SHA256(server_seed)            -> published on the game

Fixed message (known before any entry):
  message(c) = "PVPCasino:jackpot:v1:" + game_id + ":" + draw_version + ":" + c

After entries close (N = final pot in cents = ticket count):
  limit = floor(2^64 / N) * N
  for c = 0, 1, 2, ...:
    h = HMAC-SHA256(key = server_seed, data = message(c))
    r = first 8 bytes of h, big-endian unsigned 64-bit
    if r < limit: winning_ticket = r mod N; stop       (rejection sampling: no modulo bias)
  winner = entry with ticket_start <= winning_ticket < ticket_end

After settlement: server_seed is revealed on the game record.

What this does and doesn't prove

• The seed was fixed before any entry: its hash was public from the moment the round opened.
• The draw input has no free parameter: the message is fully determined by the game number and protocol version.
• Ticket mapping is integer-only and unbiased thanks to rejection sampling.
• Limitation: the operator generates the seed alone. A future version will mix in an independent randomness source before any real-money use.

Verify a draw

Or open any completed game and press “Verify”.

Coinflip protocol v1

Uses the same seed-commitment engine as Jackpot, with its own message prefix so results from one game can never be reused for another.

When the game is created (before any opponent exists):
  server_seed      = 32 random bytes (CSPRNG, Postgres pgcrypto)
  server_seed_hash = SHA256(server_seed)            -> published on the game

Fixed message (no free parameter):
  message = "PVPCasino:coinflip:v1:" + game_id + ":" + draw_version

  h    = HMAC-SHA256(key = server_seed, data = UTF-8(message))
  side = (h[0] & 1) == 0 ? HEADS : TAILS             (exactly 50/50: one bit)

The result is fixed when the opponent joins, hidden until the flip starts,
and the seed is revealed once the game is settled.

Verify a coinflip

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