Wallfair Crash Game

Introduction

This backend contains the backend functionality for the Wallfair Crash Game. The main functions are as follows:

• Start first game ever
• Start function
  • Decides on crash factor
  • Notifies users that game started
  • Schedules the end function
• End function
  • Notifies listeners that game ended
  • Schedules the next start function
• Handle failures and job retries
• Handle concurrency with locks

Provably fair algorithm

Current 10 000 000 (secured/hashes.txt) based on block:

Current max rows in file is: 2,147,483,647 (INT type which we are using for PG)

https://etherscan.io/block/13626940
Mined by #HASH
PUBLIC SEED

How to generate hashes for development use

1. Pull latest @wallfair/commons package https://github.com/wallfair-organization/wallfair-commons
2. Create a file to store hashes at wallfair-commons/scripts/provably-fair/output/hashes.txt
3. Run wallfair-commons/scripts/provably-fair/generateHashes with GENESIS_SECRET environment variable specified.
4. Copy hashes.txt to crash_game_backend/secured
5. put HASH_SEED in .env, its public seed will be used for crash-factor calculation / verification (jsfiddle): Currently used public seeds:
   • Elon game: 0xea674fdde714fd979de3edf0f56aa9716b898ec8
   • Pump and dump: 0x45a36a8e118c37e4c47ef4ab827a7c9e579e11e2

API

Obtain current info

REQUEST:
GET/api/current

RESPONSE:
200 OK
{
    timeStarted: Date,
    nextGameAt: Date,
    state: "STARTED|ENDED",
    currentBets: [],
    lastCrashes: [Number]
}

Place a trade

REQUEST:
POST /api/trade
{
    "amount": 13,
    "crashFactor": 1.1276
}

RESPONSE:
200 OK

Notifications

Game starts

{
    to: GAME_NAME,
    event: "CASINO_START",
    data: {
        gameId: "Id of the next round",
        gameName: "Name of the game that is starting"
    }
}

Game ends

{
    to: GAME_NAME,
    event: "CASINO_END",
    data: {
        crashFactor: "Final crash factor decided",
        gameId: "Id of the round that has just ended",
        gameName: "Name of the game that is ending"
    }
}

User places bet

{
    to: GAME_NAME,
    event: "CASINO_TRADE",
    data: {
        amount: "Amount of tokens staked by user",
        crashFactor: "Crash factor guess by user",
        username: "Username of the user"
    }
}

User receives reward

{
    to: winner.userid,
    event: "CASINO_REWARD",
    data: {
        crashFactor: "Crash factor decided by player",
        gameId: "Id of the game where bet was placed",
        gameName: "Name of the game",
        stakedAmount: "Original amount staked by user",
        reward: "Final reward won by user"
    }
}

Provably fair

Related env variables names:

• HASH_SEED - PUBLIC SEED, hash from BTC block
• CRASHGAME_SEED_SECRET - based on this we will generate hashes chain for crash game (2_000_000) when crash game start and store it in memory

Elon game public seed:

//Hash from BTC block #XXXXX.
// https://www.blockchain.com/btc/block/713947
// AS
// public seed
const PUBLIC_SEED = '0000000000000000000b67781ed2770ccf35c15006de5df06efa99a65323b82f';

Pump Dump game public seed:

//Hash from BTC block #XXXXX.
// https://www.blockchain.com/btc/block/713946
// AS
// public seed
const PUBLIC_SEED = '0000000000000000000b4984b5442f1059816a4065fa0f21cbf61d816dc2fa64';

Additional Info

Author: Guilherme Mussi, Lead Engineer

License: AGPL 3.0