Our system determines the result for Roulette each round by hashing a combination of two inputs.

A Server Seed is generated at the start of the game. The hashed version of the Server Seed is provided to every user on the Roulette page. The EOS Block Hash comes from a future EOS Block. Because the EOS Block Hash of a future block is unknown when the game begins, predicting the outcome of a round before it is played is impossible.

• Server Seed: a SHA-256 hash of 32 cryptographically secure random bytes.
• EOS Block Hash: A unique identifier for an EOS block mined from the EOS blockchain. The block is chosen at the start of the round, ensuring we have no control over the input.

For independent verification, you may replicate the results of any round by using the code below.

    /**
 * This module provides functions for generating random rolls in a gaming system.
 * The randomness is achieved using a combination of server seed, client seed, and EOS block hash.
 */
import { createHmac } from 'node:crypto'

/**
 * Roll function to generate random numbers
 * @param seed
 * @param entropy
 * @param nonce
 * @param rollCount
 * @returns returns an array of floats ranging from 0 (inclusive) to 1 (inclusive)
 */
function roll({
  seed,
  entropy,
  nonce,
  rollCount,
}: {
  seed: string
  entropy: string
  nonce: number
  rollCount: number
}): number[] {
  const chunk = (arr: number[], n: number): number[][] =>
    arr
      .slice(0, ((arr.length + n - 1) / n) | 0)
      .map((_, i) => arr.slice(n * i, n * i + n))

  function* byteGenerator({
    seed,
    entropy,
    nonce,
    cursor,
  }: {
    seed: string
    entropy: string
    nonce: number
    cursor: number
  }): Generator {
    // Setup cursor variables
    let currentRound = Math.floor(cursor / 32)
    let currentRoundCursor = cursor
    currentRoundCursor -= currentRound * 32

    // Generate outputs until cursor requirement fulfilled
    while (true) {
      // HMAC function used to output provided inputs into bytes
      const hmac = createHmac('sha256', seed)
      hmac.update(`${entropy}:${nonce}:${currentRound}`)
      const buffer = hmac.digest()

      // Update cursor for next iteration of loop
      while (currentRoundCursor < 32) {
        yield Number(buffer[currentRoundCursor])
        currentRoundCursor += 1
      }
      currentRoundCursor = 0
      currentRound += 1
    }
  }

  const generateFloats = ({
    seed,
    entropy,
    nonce,
    cursor,
    count,
  }: {
    seed: string
    entropy: string
    nonce: number
    cursor: number
    count: number
  }): number[] => {
    // Random number generator function
    const rng = byteGenerator({ seed, entropy, nonce, cursor })
    // Declare bytes as empty array
    const bytes: number[] = []

    // Populate bytes array with sets of 4 from RNG output
    while (bytes.length < count * 4) {
      bytes.push(rng.next().value)
    }

    // Return bytes as floats using lodash reduce function
    return chunk(bytes, 4).map(bytesChunk =>
      bytesChunk.reduce((result: number, value: number, i: number) => {
        const divider = 256 ** (i + 1)
        const partialResult = value / divider
        return result + partialResult
      }, 0),
    )
  }

  function getRolls(
    seed: string,
    entropy: string,
    nonce: number,
    count: number,
  ) {
    return generateFloats({
      seed,
      entropy,
      nonce,
      cursor: 0,
      count,
    })
  }

  return getRolls(seed, entropy, nonce, rollCount)
}

function rollMany({
  seed,
  entropy,
  rollCount,
  manyCount,
}: {
  seed: string
  entropy: string
  rollCount: number
  manyCount: number
}): number[][] {
  let nonce: number = 0
  return Array.from({ length: manyCount }, () => {
    nonce++
    return roll({
      seed,
      entropy,
      nonce,
      rollCount,
    })
  })
}

/**
 * Helper function to get the result of a roulette round.
 *
 * @param seed - The server seed (unhashed), which is generated at game initialization.
 * @param eosBlockHash - The EOS block hash used as an additional input for randomness.
 * @returns The result of the roulette round. The result can be 'RED', 'BLACK', or 'GREEN'.
 * @example
 * getRouletteOutcome({
 *   seed: 'bc6dd40a3d992f6af19dec8a3b7143fe7f28b105434c567869de4f74de077384',
 *   eosBlockHash:
 *     '164dfa0a77db58df5c2454c8b6fc4c697e2e3bc0d5dc16a4f20092ebfe0304f2',
 * });
 */
function getRouletteOutcome({
  seed,
  eosBlockHash,
}: {
  seed: string
  eosBlockHash: string
}): string {
  const result = roll({
    seed,
    entropy: eosBlockHash,
    nonce: 1,
    rollCount: 1,
  })

  const pfOutcome = result[0]

  const outcome = Math.floor(pfOutcome * 15)

  /**
   * The roulette wheel is divided into 15 slots:
   * - 0 is GREEN
   * - 1-7 are RED
   * - 8-14 are BLACK
   * - 1 and 14 are RED_BAIT and BLACK_BAIT respectively. Both the color and bait win.
   */

  let rouletteResult: 'GREEN' | 'RED' | 'RED_BAIT' | 'BLACK' | 'BLACK_BAIT'

  if (outcome === 0) {
    rouletteResult = 'GREEN'
  }
  else if (outcome <= 7 && outcome >= 1) {
    if (outcome === 1) {
      rouletteResult = 'RED_BAIT'
    }
    else {
      rouletteResult = 'RED'
    }
  }
  else if (outcome <= 14 && outcome >= 8) {
    if (outcome === 14) {
      rouletteResult = 'BLACK_BAIT'
    }
    else {
      rouletteResult = 'BLACK'
    }
  }
  else {
    throw new Error('Invalid roll value')
  }

  return rouletteResult
}

/**
 * Helper function to get a Mines board.
 *
 * @param seed The server seed (unhashed), which is saved on your profile. The unhashed version is provided once you rotate your account active seed pair.
 * @param nonce Be nonce of seed pair
 * @param entropy Client seed
 * @param mineCount Number of mines
 * @returns a 2D array representing the Mines board
 * @example
 * getMinesOutcome({
 *   seed: '655c850574b58409c124d6b266e4e8e618732a07a2e00454cdb59de6f711540c',
 *   nonce: 10,
 *   entropy: '47eb564l52y',
 *   mineAmount: 10,
 * });
 */
const GRID_WIDTH = 5 as const
const GRID_HEIGHT = 5 as const

function getMinesOutcome({
  seed,
  nonce,
  entropy,
  mineAmount,
}: {
  seed: string
  nonce: number
  entropy: string
  mineAmount: number
}): { type: string, uncovered: boolean }[][] {
  const result = roll({
    seed,
    entropy,
    nonce,
    rollCount: mineAmount,
  })

  const newBoard: { type: string, uncovered: boolean }[][] = Array.from(
    { length: 5 },
    () =>
      Array(5).fill({
        type: 'SAFE',
        uncovered: false,
      }) as { type: string, uncovered: boolean }[],
  )

  const minePositions = generateRandomMinesPositions(result)

  for (const minePosition of minePositions) {
    const { row, col } = minePosition
    newBoard[row][col] = { type: 'MINE', uncovered: false }
  }

  return newBoard
}

function generateRandomMinesPositions(
  randomFloats: number[],
): { row: number, col: number }[] {
  const potentialPositions: { row: number, col: number }[] = []

  for (let x = 0; x < GRID_WIDTH; x++) {
    for (let y = 0; y < GRID_HEIGHT; y++) {
      const newPosition = { row: x, col: y }
      potentialPositions.push(newPosition)
    }
  }

  const randomPositions = randomFloats.map((randomFloat) => {
    const randomIndex = Math.floor(randomFloat * potentialPositions.length)
    const [randomPosition] = potentialPositions.splice(randomIndex, 1)
    return randomPosition
  })

  return randomPositions
}

/**
 * Helper function to get case ticket
 *
 * @param seed The server seed (unhashed), which is saved on your profile. The unhashed version is provided once you rotate your account active seed pair.
 * @param nonce Be nonce of seed pair
 * @param entropy Client seed
 * @param rollCount Number of cases you open (1-4)
 * @returns a array representing the case ticket per roll
 * @example
 * getCaseUnboxOutcome({
 *   seed: '9424a6362c807cceb6aa89bc9dcafc433994543deed9e7c807dda880e0dd7b25',
 *   nonce: 0,
 *   entropy: '47eb564l52y',
 *   rollCount: 1,
 * });
 */
function getCaseUnboxOutcome({
  seed,
  nonce,
  entropy,
  rollCount,
}: {
  seed: string
  nonce: number
  entropy: string
  rollCount: number
}): { roll: number, ticket: number }[] {
  const MAX_TICKET_COUNT = 100000

  const result: number[] = roll({
    seed,
    entropy,
    nonce,
    rollCount,
  })

  const tickets: { roll: number, ticket: number }[] = []

  for (let i = 0; i < rollCount; i++) {
    tickets.push({
      roll: i,
      ticket: result[i] * MAX_TICKET_COUNT,
    })
  }

  return tickets
}

/**
 * Helper function to get case battle outcome
 * @param seed
 * @param eosBlockHash
 * @param rounds
 * @param players
 * @returns returns an array of each player's ticket per round. The ticket can be bound to the item of the case that is being played in the round.
 * @example
 * getCaseBattleOutcome({
 *     seed: '73884c92de9eba6ede0734cc2423a1e3a95af39ac50efca45cbf91f666263fe9',
 *     eosBlockHash:
 *       '168ccd760261a8da6728fd2f52daa08eae33339b49fcca863c5bc258bf576d23',
 *     rounds: 5,
 *     players: 3,
 *   }),
 */
function getCaseBattleOutcome({
  seed,
  eosBlockHash,
  rounds,
  players,
}: {
  seed: string
  eosBlockHash: string
  rounds: number
  players: number
}): { round: number, player: number, ticket: number }[] {
  const result: number[][] = rollMany({
    seed,
    entropy: eosBlockHash,
    rollCount: rounds,
    manyCount: players,
  })

  const MAX_TICKET_COUNT = 100000

  const totalRounds: number = rounds * players

  const tickets: { round: number, player: number, ticket: number }[] = []

  for (let i = 0; i < totalRounds; i++) {
    const round: number = Math.floor(i / players)
    const player: number = i % players
    const ticket: number = result[player][round] * MAX_TICKET_COUNT
    tickets.push({ round: round + 1, player: player + 1, ticket })
  }

  return tickets
}

/**
 * Helper function to get Plinko outcome
 *
 * The result is array for each ball and its outcome on the board. The outcome is the slot number where the ball ends up (starting from index 0).
 *
 * @param seed The server seed (unhashed), which is saved on your profile. The unhashed version is provided once you rotate your account active seed pair.
 * @param nonce Be nonce of seed pair
 * @param entropy Client seed
 * @param rowAmount Number of rows in the Plinko game
 * @param rollCount Plinko row amount multiplied with the ball count
 * @returns a array representing the case ticket per roll
 * @example
 * getPlinkoOutcome({
 *  seed: 'e6d924a5a7d13850cc213abd65935104f18cbd28115b8eb444331613fbd5f3c6',
 *  nonce: 0,
 *  entropy: '47eb564l52y',
 *  rowAmount: 12,
 *  ballCount: 1,
 * }),
 */
function getPlinkoOutcome({
  seed,
  nonce,
  entropy,
  rowAmount,
  ballCount,
}: {
  seed: string
  nonce: number
  entropy: string
  rowAmount: number
  ballCount: number
}): number[] {
  const rollCount: number = rowAmount * ballCount

  const result: number[] = roll({
    seed,
    entropy,
    nonce,
    rollCount,
  })

  const trimmedResults: number[] = result.map(float =>
    Number(float.toFixed(2)),
  )

  // Initialize an empty array to store the game results
  const gameResults: number[] = []

  // Loop over the number of balls
  for (let ballIndex = 0; ballIndex < ballCount; ballIndex++) {
    const sliceStart: number = ballIndex * rowAmount
    const sliceEnd: number = (ballIndex + 1) * rowAmount

    const ballNumbers: number[] = trimmedResults.slice(sliceStart, sliceEnd)

    let outcome: number = 0 // Which slot the ball ends up in

    for (let i = 0; i < rowAmount; i++) {
      if (ballNumbers[i] > 0.5) {
        outcome++
      }
    }

    gameResults.push(outcome)
  }

  // Return the array of game results
  return gameResults
}