RNG Test Vectors: Ketapola Dice¶

Fixed (serverSeed, clientSeed, nonce, lowWeight, highWeight) → (outcomeSide, outcomeSum) triples for the Ketapola Dice game. A cert lab, operator, or independent reviewer can recompute these locally and compare bit-for-bit. Drift from this table invalidates the conceptual RNG certification for this game.

The machine-readable form is ../fixtures/rng-test-vectors.json (co-located with the test harness so Bun-test and the cert packet read the same bytes). The canonical code under test is split across packages/rng-core/src/index.ts (shared primitives) and games/ketapola-dice/src/outcome.ts (game-specific mapping). The vectors are regression-tested by tests/games/ketapola-dice/rng-test-vectors.spec.ts on every CI run.

Verification (20 lines of JS)¶

import crypto from 'node:crypto';

function verify({ serverSeed, clientSeed, nonce, lowWeight, highWeight }) {
  const hmac = crypto.createHmac('sha256', serverSeed)
    .update(`${clientSeed}:${nonce}`)
    .digest('hex');
  const sideValue = parseInt(hmac.slice(0, 8), 16);
  const threshold = (lowWeight / (lowWeight + highWeight)) * 0xffffffff;
  const side = sideValue < threshold ? 'LOW' : 'HIGH';
  const faceValue = parseInt(hmac.slice(8, 16), 16);
  const faces = side === 'LOW' ? [3, 6, 9] : [12, 15, 18];
  const sum = faces[faceValue % faces.length];
  return { outcomeSide: side, outcomeSum: sum };
}

Vectors: symmetric weights (48, 48)¶

#	serverSeed (hex)	clientSeed	nonce	→ side	sum
1	`0000…0000`	`client-seed-a`	0	LOW	3
2	`0000…0000`	`client-seed-a`	1	LOW	3
3	`0000…0000`	`client-seed-a`	2	LOW	3
4	`ffff…ffff`	`client-seed-b`	0	LOW	9
5	`deadbeefcafef00d0000000000000000000000000000000000000000deadbeef`	`operator-provided`	0	LOW	9
6	`deadbeefcafef00d0000000000000000000000000000000000000000deadbeef`	`operator-provided`	100	HIGH	15
7	`deadbeefcafef00d0000000000000000000000000000000000000000deadbeef`	`operator-provided`	1,000,000	HIGH	15

Vectors: asymmetric weights¶

#	(low, high)	serverSeed (hex)	clientSeed	nonce	→ side	sum
8	(60, 40)	`1111…1111`	`asymmetric-low`	0	LOW	6
9	(60, 40)	`1111…1111`	`asymmetric-low`	1	LOW	9
10	(40, 60)	`2222…2222`	`asymmetric-high`	0	HIGH	18

Vectors: edge cases¶

#	input property	→ side	sum
11	76-byte clientSeed (`a-much-longer-client-seed-that-exceeds-the-default-16-bytes-by-a-wide-margin`) with `3333…3333` seed	LOW	6
12	UTF-8 clientSeed (Sinhala `කැටපොල`) with `4444…4444` seed	HIGH	12

Full seeds (for copy-paste)¶

The 0000…0000, ffff…ffff, 1111…1111, 2222…2222, 3333…3333, 4444…4444 seeds in the tables above are each 32 bytes of the same hex character repeated. The single non-trivial seed in full:

deadbeefcafef00d0000000000000000000000000000000000000000deadbeef

Regenerating¶

These vectors are produced by scripts/generate-test-vectors.ts. Rerunning that script must produce byte-identical output, if it does not, the RNG has changed and requires a CERT-ATTEST: line on the PR (enforced by the rng-change-gate CI job).

bun scripts/generate-test-vectors.ts > /tmp/actual.json
diff games/ketapola-dice/fixtures/rng-test-vectors.json /tmp/actual.json   # must be empty