Fairness Protocol

§1

Math model — multipliers, not money

Every engine output is a multiplier expressed as multiples of one bet unit. The engine never handles currency. Operators compute monetary payouts as:

line_payout  = win_multiplier   × bet_per_line × denomination
total_payout = total_multiplier × bet_per_line × denomination

Bet units by win mode

The units divisor converts a per-total-bet multiplier into a per-line-bet multiplier so that Σ breakdown == totalMultiplier holds exactly.

If max_win_multiplier is set, the capped bucket of the breakdown is bounded by cap = max_win_multiplier × units. Exact clipping rules — including bucket priority and the dynamic-grid free-spin anchor — are described in the full math model.

§2

RNG protocol

Outcome space

Every random decision is driven by a sequence of outcome floats in [0, 1) with 52-bit precision (full IEEE-754 mantissa).

Derivation

Outcomes are derived in batches of four from HMAC-SHA256:

OUTCOMES_PER_HASH = 4
OUTCOME_DIVISOR   = 2^52

deriveBatch(server_seed, client_seed, nonce, hashIndex):
  message = client_seed + ":" + nonce + ":slots"
  hmac    = HMAC_SHA256(key = server_seed, data = message + ":" + hashIndex)
  hex     = hmac.hex_digest()             # 64 hex chars
  outcomes = []
  for i in 0..3:
    chunk = hex[i*13 : (i+1)*13]          # 13 hex digits
    value = int(chunk, 16) / OUTCOME_DIVISOR
    outcomes.append(value)
  return outcomes

hashIndex starts at 0 and increments by 1 per batch. The engine pulls one batch at a time, lazily, in deterministic consumption order.

Consumption order

Outcomes are consumed in a single deterministic order, identical across implementations:

The order is invariant. Any implementation consuming outcomes in a different order will diverge.

Replay and verification

Given (config, server_seed, client_seed, nonce, player_choices, external_state), the engine produces byte-identical results. The engine pre-commits to a server seed by publishing sha256(server_seed); after the seed is rotated, the prior seed is revealed and any past spin can be independently re-derived and its result_hash verified.

§17

Output format and result hash

Result envelope

{
  "round_id": "01ARZ3...",
  "spins": [
    { "type": "base", "reel_positions": [...], "wins": [...], "win_total": 12.5 },
    { "type": "cascade", "iteration": 1 },
    { "type": "hold_respin", "respin_index": 1 },
    { "type": "free_spin", "spin_index": 0, "win_total": 20.0 }
  ],
  "summary": { "total_multiplier": 42.5, "win_capped": false, "breakdown": { ... } },
  "state":   { "meters": {...}, "jackpot_pools": {...} },
  "result_hash": "d4e5f6..."
}

Canonical encoding

The result_hash is HMAC-SHA256 of a canonically encoded form of the rest of the response, keyed by the server seed:

result_hash = HMAC_SHA256(
  key  = server_seed,
  data = canonicalEncode( result_without_hash )
)

canonicalize(value):
  if value is not object/array: return value
  for each (k, v) in value: value[k] = canonicalize(v)
  if value is an associative object (not a list): sort keys ascending
  return value

canonicalEncode(value) = json_encode(
  canonicalize(value),
  JSON_UNESCAPED_SLASHES | JSON_UNESCAPED_UNICODE | JSON_PRESERVE_ZERO_FRACTION
)

A naive json_encode will not match — PHP and JavaScript do not guarantee object-key order, and JSON_PRESERVE_ZERO_FRACTION is required so integer-valued floats (e.g. 1.0) serialize with the trailing .0 the engine emitted.