mental-poker-toolkit

Toolkit for implementing mental poker games.

Usage

Install the package.

npm install mental-poker-toolkit

And then, either require or import the library.

require('mental-poker-toolkit');

or

import * as MentalPokerToolkit from 'mental-poker-toolkit';

Here is a step-by-step example following the algorithm explained on Wikipedia.

// 1. Alice and Bob agree on a certain "deck" of cards
const deck = getStandard52Deck();
const deckEncoded = new EncodedDeck(
  deck.map((card) => BigInt(encodeStandardCard(card)))
);

// 2. Alice picks an encryption key A.
const alice = await createPlayer({
  cards: deck.length,
  bits: 32,
});

// 3. Alice uses this to encrypt each card of the deck and shuffles the cards.
const encryptedWithKeyA = alice.encryptAndShuffle(deckEncoded);

// 4. Alice passes the encrypted and shuffled deck to Bob.
// ignored, since it varies.

// 5. Bob picks an encryption key B.
const sharedPublicKey = alice.publicKey;
const bob = await createPlayer({
  cards: deck.length,
  publicKey: sharedPublicKey,
  bits: 32,
});

// 6. Bob uses this to encrypt each card of the encrypted and shuffled deck and shuffles the deck.
const encryptedWithKeyAKeyB = bob.encryptAndShuffle(encryptedWithKeyA);

// 7. Bob passes the double encrypted and shuffled deck back to Alice.
// ignored, since it varies.

// 8 & 9. Alice decrypts each card using her key A.
//        Alice picks one encryption key for each card (A1, A2, etc.) and encrypts them individually.
const encryptedWithIndividualKeyAKeyB = alice.decryptAndEncryptIndividually(
  encryptedWithKeyAKeyB
);

// 10. Alice passes the deck to Bob.
// ignored, since it varies.

// 11 & 12. Bob decrypts each card using his key B.
//          Bob picks one encryption key for each card (B1, B2, etc.) and encrypts them individually.
const encryptedBothKeysIndividually = bob.decryptAndEncryptIndividually(
  encryptedWithIndividualKeyAKeyB
);

// 13. Bob passes the deck back to Alice.
// 14. Alice publishes the deck for everyone playing.
// ignored, since it varies.

// Finally, when any player wants to see their cards,
// they will request the corresponding keys from both Alice and Bob.
const doubleEncryptedCard = encryptedBothKeysIndividually.cards[offset];
const aliceIndividualKey = alice.getIndividualKey(offset);
const bobIndividualKey = bob.getIndividualKey(offset);

const decryptedCard = bobIndividualKey.decrypt(
  aliceIndividualKey.decrypt(doubleEncryptedCard));

console.log(`suit = ${decryptedCard.suit}, rank = ${decryptedCard.rank}`);

This project is also being used by mental-texas-holdem to implement a P2P Texas Hold'em poker game in browsers. Please see MentalPokerGameRoom.ts for a real-world example.

API Reference

For more information, please see the API reference doc.